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Search for "indoline" in Full Text gives 80 result(s) in Beilstein Journal of Organic Chemistry.
Synthesis of the tetracyclic skeleton of Aspidosperma alkaloids via PET-initiated cationic radical-derived interrupted [2 + 2]/retro-Mannich reaction
- Ru-Dong Liu,
- Jian-Yu Long,
- Zhi-Lin Song,
- Zhen Yang and
- Zhong-Chao Zhang
Beilstein J. Org. Chem. 2025, 21, 2470–2478, doi:10.3762/bjoc.21.189
- formation of unique radical intermediates [9][10]. We previously demonstrated the Ir-catalyzed [2 + 2] cyclization/retro-Mannich reaction of a tryptamine-substituted cyclopentenone F, which led to the formation of indoline J (Figure 1b) [15]. Unlike other reported methods [16][17][18], the PET reaction of F
- tetracyclic indoline M, which was expected to serve as a common intermediate for the total synthesis of Aspidosperma alkaloids. These alkaloids constitute a large family of structurally complex compounds, which incorporate a pentacyclic ABCDE skeleton (Figure 1d, 1–8) [19][20][21][22][23]. However, the
Graphical Abstract
Figure 1: Synthetic plan. a) General model of cyclobutenone bond cleavage; b) our previously reported method;...
Scheme 1: Substrate scope.
Figure 2: Computational study. a) Energy profiles from IN1 to IN3 and spin density of TS2 (isovalue = 0.004),...
An Fe(II)-catalyzed synthesis of spiro[indoline-3,2'-pyrrolidine] derivatives
- Elizaveta V. Gradova,
- Nikita A. Ozhegov,
- Roman O. Shcherbakov,
- Alexander G. Tkachenko,
- Larisa Y. Nesterova,
- Elena Y. Mendogralo and
- Maxim G. Uchuskin
Beilstein J. Org. Chem. 2025, 21, 2383–2388, doi:10.3762/bjoc.21.183
- , The Ural Branch of Russian Academy of Sciences, Goleva St. 13, 614081 Perm, Russian Federation 10.3762/bjoc.21.183 Abstract A synthetic strategy for the preparation of spiro[indoline-3,2'-pyrrolidine] derivatives has been developed, featuring a two-step sequence consisting of the reaction of 2
- -unsaturated ketone; dearomatization; indole; spirocyclization; spiro[indoline-3,2'-pyrrolidine]; Introduction Spiro[indoline-3,2'-pyrrolidine] derivatives represent an important class of organic compounds found in both natural products (e.g., coerulescine [1], horsfiline [2], and elacomine [3]) and synthetic
- activities, spiro[indoline-3,2'-pyrrolidines] have attracted substantial interest in medicinal chemistry, prompting the development of diverse synthetic strategies. Several methodologies have been reported for the synthesis of substituted spiro[indoline-3,2'-pyrrolidines] (Scheme 1), which can be broadly
Graphical Abstract
Figure 1: Natural and synthetic bioactive spiro[indoline-3,2'-pyrrolidine] derivatives.
Scheme 1: Previous approaches and our work.
Scheme 2: The reaction of 2-arylindoles 1 with α,β-unsaturated ketones 2. aIsolated yield of the 5 mmol scale...
Scheme 3: The scope of the Fe-catalyzed spirocyclization. aIsolated yield of the 4.2 mmol scale experiment.
Scheme 4: The proposed mechanism of product 4 formation.
Pathway economy in cyclization of 1,n-enynes
- Hezhen Han,
- Wenjie Mao,
- Bin Lin,
- Maosheng Cheng,
- Lu Yang and
- Yongxiang Liu
Beilstein J. Org. Chem. 2025, 21, 2260–2282, doi:10.3762/bjoc.21.173
- afforded selective access to four indole derivatives through modulation of the alkyne's terminal substituents and nucleophile type (Scheme 14) [21][22]. The gold(I) catalyst activated the unsubstituted terminal alkynes to initiate a 5-exo-dig cyclization, generating a spiro[indoline-3,3'-pyrrolidine
- . In contrast, when the alkyne was substituted with a phenyl group, the reaction shifted toward a 6-endo-dig cyclization pathway due to steric and electronic effects (Scheme 14, path b). When HEH was employed as the nucleophile, a spiro[indoline-3,3'-piperidine] framework 66 was formed. When indole
- acted as nucleophile, the stable imine–gold–aryl cation–π–π interaction precluded rearrangement and promoted the capture of imine to form spiro[indoline-3,3'-pyridine] derivatives 67. The Ph3PAuCl/AgNTf2-catalyzed cyclization of N-propargyl-tethered amide enynes efficiently afforded four distinct
Graphical Abstract
Scheme 1: Economical synthesis and pathway economy.
Scheme 2: Au(I)-catalyzed cascade cyclization paths of 1,5-enynes.
Scheme 3: Au(I)-catalyzed cyclization paths of 1,7-enynes.
Scheme 4: I2/TBHP-mediated radical cycloisomerization paths of 1,n-enyne.
Scheme 5: Au(I)-catalyzed cycloisomerization paths of 3-allyloxy-1,6-diynes.
Scheme 6: Pd(II)-catalyzed cycloisomerization paths of 2-alkynylbenzoate-cyclohexadienone.
Scheme 7: Stereoselective cyclization of 1,5-enynes.
Scheme 8: Substituent-controlled cycloisomerization of propargyl vinyl ethers.
Scheme 9: Au(I)-catalyzed pathway-controlled domino cyclization of 1,2-diphenylethynes.
Scheme 10: Au(I)-catalyzed tandem cyclo-isomerization of tryptamine-N-ethynylpropiolamide.
Scheme 11: Au(I)-catalyzed tunable cyclization of 1,6-cyclohexenylalkyne.
Scheme 12: Substituent-controlled 7-exo- and 8-endo-dig-selective cyclization of 2-propargylaminobiphenyl deri...
Scheme 13: BiCl3-catalyzed cycloisomerization of tryptamine-ynamide derivatives.
Scheme 14: Au(I)-mediated substituent-controlled cycloisomerization of 1,6-enynes.
Scheme 15: Ligand-controlled regioselective cyclization of 1,6-enynes.
Scheme 16: Ligand-dependent cycloisomerization of 1,7-enyne esters.
Scheme 17: Ligand-controlled cycloisomerization of 1,5-enynes.
Scheme 18: Ligand-controlled cyclization strategy of alkynylamide tethered alkylidenecyclopropanes.
Scheme 19: Ag(I)-mediated pathway-controlled cycloisomerization of tryptamine-ynamides.
Scheme 20: Gold-catalyzed cycloisomerization of indoles with alkynes.
Scheme 21: Catalyst-dependent cycloisomerization of dienol silyl ethers.
Scheme 22: Cycloisomerization of aromatic enynes governed by catalyst.
Scheme 23: Catalyst-dependent 1,2-migration in cyclization of 1-(indol-2-yl)-3-alkyn-1-ols.
Scheme 24: Gold-catalyzed cycloisomerization of N-propargyl-N-vinyl sulfonamides.
Scheme 25: Gold(I)-mediated enantioselective cycloisomerizations of ortho-(alkynyl)styrenes.
Scheme 26: Catalyst-controlled intramolecular cyclization of 1,7-enynes.
Scheme 27: Brønsted acid-catalyzed cycloisomerizations of tryptamine ynamides.
Scheme 28: Catalyst-controlled cyclization of indolyl homopropargyl amides.
Scheme 29: Angle strain-dominated 6-endo-trig cyclization of propargyl vinyl ethers.
Scheme 30: Angle strain-controlled cycloisomerization of alkyn-tethered indoles.
Scheme 31: Geometrical isomeration-dependent cycloisomerization of 1,3-dien-5-ynes.
Scheme 32: Temperature-controlled cyclization of 1,7-enynes.
Scheme 33: Cycloisomerizations of n-(o-ethynylaryl)acrylamides through temperature modulation.
Scheme 34: Temperature-controlled boracyclization of biphenyl-embedded 1,3,5-trien-7-ynes.
Enantioselective desymmetrization strategy of prochiral 1,3-diols in natural product synthesis
- Lihua Wei,
- Rui Yang,
- Zhifeng Shi and
- Zhiqiang Ma
Beilstein J. Org. Chem. 2025, 21, 1932–1963, doi:10.3762/bjoc.21.151
- dihydroxyketone 216 in two steps, Sonogashira coupling with indoline 218 followed by acetylation afforded compound 219. A Au-catalyzed cyclization and subsequent saponification with NaOMe gave indoline 220. Three subsequent steps yielded diol 221, which was treated with vinyl benzoate and a Zn-complex derived
- underwent a reductive interrupted Fisher indolization with phenylhydrazine to give indoline 281. To forge the C16 stereocenter and form the C–O bond at C2, diol 282 was prepared from 281 in six steps. Treatment of 282 with MeI/Cs2CO3 induced cyclization through putative indoleninium intermediate 283
Graphical Abstract
Scheme 1: General mechanism of a lipase-catalyzed esterification.
Scheme 2: Shishido’s synthesis of (−)-xanthorrhizol (4) and (+)-heliannuol D (8).
Scheme 3: Shishido’s synthesis of a) (−)-heliannuol A (15) and b) heliannuol G (20) and heliannuol H (21).
Scheme 4: Deska’s synthesis of hyperione A (30) and ent-hyperione B (31).
Scheme 5: Huang’s synthesis of (+)-brazilin (37).
Scheme 6: Shishido’s synthesis of (−)-heliannuol D (42) and (+)-heliannuol A (43).
Scheme 7: Chênevert’s synthesis of (S)-α-tocotrienol (49).
Scheme 8: Kita’s synthesis of monoester 53.
Scheme 9: Kita’s synthesis of fredericamycin A (60).
Scheme 10: Takabe’s synthesis of (E)-3,7-dimethyl-2-octene-1,8-diol (64).
Scheme 11: Takabe’s synthesis of (18S)-variabilin (70).
Scheme 12: Kawasaki’s synthesis of (S)-Rosaphen (74) and (R)-Rosaphen (75).
Scheme 13: Tokuyama’s synthesis of a) (−)-petrosin (84) and b) (+)-petrosin (86).
Scheme 14: Fukuyama’s synthesis of leustroducsin B (96).
Scheme 15: Nanda’s synthesis of a) fragment 100, b) fragment 106 and c) (−)-rasfonin (109).
Scheme 16: Davies’ synthesis of (+)-pilocarpine (115) and (+)-isopilocarpine (116).
Scheme 17: Ōmura’s synthesis of salinosporamide A (125).
Scheme 18: Kang’s synthesis of ʟ-cladinose (124) and its derivative.
Scheme 19: Kang’s preparation of fragment 139.
Scheme 20: Kang’s synthesis of azithromycin (149).
Scheme 21: Kang’s synthesis of (−)-dysiherbaine (156).
Scheme 22: Kang’s synthesis of (−)-kaitocephalin (166).
Scheme 23: Kang’s synthesis of laidlomycin (180).
Scheme 24: Snyder’s synthesis of arboridinine (190).
Scheme 25: Ma’s synthesis of (+)-alstrostine G (203).
Scheme 26: Trost’s synthesis of (−)-18-epi-peloruside A (215).
Scheme 27: Lindel’s synthesis of (–)-dihydroraputindole (223).
Scheme 28: Iwata’s synthesis of a) (−)-talaromycin B (232) and b) (+)-talaromycin A (235).
Scheme 29: Cook’s synthesis of a) (−)-vincamajinine (240) and b) (−)-11-methoxy-17-epivincamajine (245).
Scheme 30: Cook’s synthesis of (+)-dehydrovoachalotine (249) and voachalotine (250).
Scheme 31: Cook’s synthesis of a) (−)-12-methoxy-Nb-methylvoachalotine (257) and b) (+)-polyneuridine, macusin...
Scheme 32: Trauner’s synthesis of stephadiamine (273).
Scheme 33: Garg’s synthesis of (–)-ψ-akuammigine (285).
Scheme 34: Ding’s synthesis of (+)-18-benzoyldavisinol (293) and (+)-davisinol (294).
Photoswitches beyond azobenzene: a beginner’s guide
- Michela Marcon,
- Christoph Haag and
- Burkhard König
Beilstein J. Org. Chem. 2025, 21, 1808–1853, doi:10.3762/bjoc.21.143
Graphical Abstract
Figure 1: Energy diagram of a two-state photoswitch. Figure 1 was redrawn from [2].
Figure 2: Example of the absorption spectra of the isomers of a photoswitch with most efficient irradiation w...
Scheme 1: Photoswitch classes described in this review.
Figure 3: Azoheteroarenes.
Scheme 2: E–Z Isomerisation (top) and mechanisms of thermal Z–E isomerisation (bottom).
Scheme 3: Rotation mechanism favoured by the electron displacement in push–pull systems. Selected examples of...
Figure 4: A) T-shaped and twisted Z-isomers determine the thermal stability and the Z–E-PSS (selected example...
Figure 5: Effect of di-ortho-substitution on thermal half-life and PSS.
Figure 6: Selected thermal lifetimes of azoindoles in different solvents and concentrations. aConcentration o...
Figure 7: Aryliminopyrazoles: N-pyrazoles (top) and N-phenyl (bottom).
Scheme 4: Synthesis of symmetrical heteroarenes through oxidation (A), reduction (B), and the Bayer–Mills rea...
Scheme 5: Synthesis of diazonium salt (A); different strategies of azo-coupling: with a nucleophilic ring (B)...
Scheme 6: Synthesis of arylazothiazoles 25 (A) and heteroaryltriazoles 28 (B).
Scheme 7: Synthesis of heteroarylimines 31a,b [36-38].
Figure 8: Push–pull non-ionic azo dye developed by Velasco and co-workers [45].
Scheme 8: Azopyridine reported by Herges and co-workers [46].
Scheme 9: Photoinduced phase transitioning azobispyrazoles [47].
Figure 9: Diazocines.
Scheme 10: Isomers, conformers and enantiomers of diazocine.
Scheme 11: Partial overlap of the ππ* band with electron-donating substituents and effect on the PSS. Scheme 11 was ada...
Figure 10: Main properties of diazocines with different bridges. aMeasured in n-hexane [56]. bMeasured in THF. cMe...
Scheme 12: Synthesis of symmetric diazocines.
Scheme 13: Synthesis of asymmetric diazocines.
Scheme 14: Synthesis of O- and S-heterodiazocines.
Scheme 15: Synthesis of N-heterodiazocines.
Scheme 16: Puromycin diazocine photoswitch [60].
Figure 11: Indigoids.
Figure 12: The main representatives of the indigoid photoswitch class.
Scheme 17: Deactivation process that prevents Z-isomerisation of indigo.
Figure 13: Stable Z-indigo derivative synthesised by Wyman and Zenhäusern [67].
Figure 14: Selected examples of indigos with aliphatic and aromatic substituents [68]. Dashed box: proposed π–π in...
Scheme 18: Resonance structures of indigo and thioindigo involving the phenyl ring.
Scheme 19: Possible deactivation mechanism for 4,4'-dihydroxythioindigo [76].
Scheme 20: Effect of different heteroaryl rings on the stability and the photophysical properties of hemiindig...
Figure 15: Thermal half-lives of red-shifted hemithioindigos in toluene [79]. aMeasured in toluene-d8.
Scheme 21: Structures of pyrrole [81] and imidazole hemithioindigo [64].
Figure 16: Examples of fully substituted double bond hemithioindigo (left), oxidised hemithioindigos (centre),...
Scheme 22: Structure of iminothioindoxyl 72 (top) and acylated phenyliminoindolinone photoswitch 73 (bottom). ...
Scheme 23: (top) Transition states of iminothioindoxyl 72. The planar transition state is associated with a lo...
Scheme 24: Baeyer–Drewsen synthesis of indigo (top) and N-functionalisation strategies (bottom).
Scheme 25: Synthesis of hemiindigo.
Scheme 26: Synthesis of hemithioindigo and iminothioindoxyl.
Scheme 27: Synthesis of double-bond-substituted hemithioindigos.
Scheme 28: Synthesis of phenyliminoindolinone.
Scheme 29: Hemithioindigo molecular motor [85].
Figure 17: Arylhydrazones.
Scheme 30: Switching of arylhydrazones. Note: The definitions of stator and rotor are arbitrary.
Scheme 31: Photo- and acidochromism of pyridine-based phenylhydrazones.
Scheme 32: A) E–Z thermal inversion of a thermally stable push–pull hydrazone [109]. B) Rotation mechanism favoured...
Scheme 33: Effect of planarisation on the half-life.
Scheme 34: The longest thermally stable hydrazone switches reported so far (left). Modulation of thermal half-...
Figure 18: Dependency of t1/2 on concentration and hypothesised aggregation-induced isomerisation.
Figure 19: Structure–property relationship of acylhydrazones.
Scheme 35: Synthesis of arylhydrazones.
Scheme 36: Synthesis of acylhydrazones.
Scheme 37: Photoswitchable fluorophore by Aprahamian et al. [115].
Scheme 38: The four-state photoswitch synthesised by the Cigáň group [116].
Figure 20: Diarylethenes.
Scheme 39: Isomerisation and oxidation pathway of E-stilbene to phenanthrene.
Scheme 40: Strategies adapted to avoid E–Z isomerisation and oxidation.
Scheme 41: Molecular orbitals and mechanism of electrocyclisation for a 6π system.
Figure 21: Aromatic stabilisation energy correlated with the thermal stability of the diarylethenes [127,129].
Figure 22: Half-lives of diarylethenes with increasing electron-withdrawing groups [128,129].
Scheme 42: Photochemical degradation pathway promoted by electron-donating groups [130].
Figure 23: The diarylethenes studied by Hanazawa et al. [134]. Increased rigidity leads to bathochromic shift.
Scheme 43: The dithienylethene synthesised by Nakatani's group [135].
Scheme 44: Synthesis of perfluoroalkylated diarylethenes.
Scheme 45: Synthesis of 139 and 142 via McMurry coupling.
Scheme 46: Synthesis of symmetrical derivatives 145 via Suzuki–Miyaura coupling.
Scheme 47: Synthesis of acyclic 148, malonic anhydride 149, and maleimide derivatives 154.
Figure 24: Gramicidin S (top left) and two of the modified diarylethene derivatives: first generation (bottom ...
Scheme 48: Pyridoxal 5'-phosphate and its reaction with an amino acid (top). The analogous dithienylethene der...
Figure 25: Fulgides.
Scheme 49: The three isomers of fulgides.
Scheme 50: Thermal and photochemical side products of unsubstituted fulgide [150].
Figure 26: Maximum absorption λc of the closed isomer compared with the nature of the aromatic ring and the su...
Scheme 51: Possible rearrangement of the excited state of 5-dimethylaminoindolylfulgide [153].
Figure 27: Quantum yields of ring closure (ΦE→C) and E–Z isomerisation (ΦE→Z) correlated with the increasing s...
Scheme 52: Active (Eα) and inactive (Eβ) conformers (left) and the bicyclic sterically blocked fulgide 169 (ri...
Scheme 53: Quantum yield of ring-opening (ΦC→E) and E–Z isomerisation (ΦE→Z) for different substitution patter...
Scheme 54: Stobbe condensation pathway for the synthesis of fulgides 179, fulgimides 181 and fulgenates 178.
Scheme 55: Alternative synthesis of fulgides through Pd-catalysed carbonylation.
Scheme 56: Optimised synthesis of fulgimides [166].
Scheme 57: Photoswitchable FRET with a fulgimide photoswitch [167].
Scheme 58: Three-state fulgimide strategy by Slanina's group.
Figure 28: Spiropyrans.
Scheme 59: Photochemical (left) and thermal (right) ring-opening mechanisms for an exemplary spiropyran with a...
Figure 29: Eight possible isomers of the open merocyanine according to the E/Z configurations of the bonds hig...
Scheme 60: pH-Controlled photoisomerisation between the closed spiropyran 191-SP and the open E-merocyanine 19...
Scheme 61: Behaviour of spiropyran in water buffer according to Andréasson and co-workers [180]. 192-SP in an aqueo...
Scheme 62: (left box) Proposed mechanism of basic hydrolysis of MC [184]. (right box) Introduction of electron-dona...
Scheme 63: Photochemical interconversion of naphthopyran 194 (top) and spirooxazine 195 (bottom) photoswitches...
Scheme 64: Synthesis of spiropyrans and spirooxazines 198 and the dicondensation by-product 199.
Scheme 65: Alternative synthesis of spiropyrans and spirooxazines with indolenylium salt 200.
Scheme 66: Synthesis of 4’-substituted spiropyrans 203 by condensation of an acylated methylene indoline 201 w...
Scheme 67: Synthesis of spironaphthopyrans 210 by acid-catalysed condensation of naphthols and diarylpropargyl...
Scheme 68: Photoswitchable surface wettability [194].
Figure 30: Some guiding principles for the choice of the most suitable photoswitch. Note that this guide is ve...
Recent advances in oxidative radical difunctionalization of N-arylacrylamides enabled by carbon radical reagents
- Jiangfei Chen,
- Yi-Lin Qu,
- Ming Yuan,
- Xiang-Mei Wu,
- Heng-Pei Jiang,
- Ying Fu and
- Shengrong Guo
Beilstein J. Org. Chem. 2025, 21, 1207–1271, doi:10.3762/bjoc.21.98
Graphical Abstract
Scheme 1: DTBP-mediated oxidative alkylarylation of activated alkenes.
Scheme 2: Iron-catalyzed oxidative 1,2-alkylarylation.
Scheme 3: Possible mechanism for the iron-catalyzed oxidative 1,2-alkylation of activated alkenes.
Scheme 4: A metal-free strategy for synthesizing 3,3-disubstituted oxindoles.
Scheme 5: Iminoxyl radical-promoted cascade oxyalkylation/alkylarylation of alkenes.
Scheme 6: Proposed mechanism for the iminoxyl radical-promoted cascade oxyalkylation/alkylarylation of alkene...
Scheme 7: Bicyclization of 1,n-enynes with alkyl nitriles.
Scheme 8: Possible reaction mechanism for the bicyclization of 1,n-enynes with alkyl nitriles.
Scheme 9: Radical cyclization of N-arylacrylamides with isocyanides.
Scheme 10: Plausible mechanism for the radical cyclization of N-arylacrylamides with isocyanides.
Scheme 11: Electrochemical dehydrogenative cyclization of 1,3-dicarbonyl compounds.
Scheme 12: Plausible mechanism for the dehydrogenative cyclization of 1,3-dicarbonyl compounds.
Scheme 13: Photocatalyzed cyclization of N-arylacrylamide and N,N-dimethylaniline.
Scheme 14: Proposed mechanism for the photocatalyzed cyclization of N-arylacrylamides and N,N-dimethylanilines....
Scheme 15: Electrochemical monofluoroalkylation cyclization of N-arylacrylamides with dimethyl 2-fluoromalonat...
Scheme 16: Proposed mechanism for the electrochemical radical cyclization of N-arylacrylamides with dimethyl 2...
Scheme 17: Photoelectrocatalytic carbocyclization of unactivated alkenes using simple malonates.
Scheme 18: Plausible mechanism for the photoelectrocatalytic carbocyclization of unactivated alkenes with simp...
Scheme 19: Bromide-catalyzed electrochemical trifluoromethylation/cyclization of N-arylacrylamides.
Scheme 20: Proposed mechanism for the electrochemical trifluoromethylation/cyclization of N-arylacrylamides.
Scheme 21: Visible light-mediated trifluoromethylarylation of N-arylacrylamides.
Scheme 22: Plausible reaction mechanism for the visible light-mediated trifluoromethylarylation of N-arylacryl...
Scheme 23: Electrochemical difluoroethylation cyclization of N-arylacrylamides with sodium difluoroethylsulfin...
Scheme 24: Electrochemical difluoroethylation cyclization of N-methyacryloyl-N-alkylbenzamides with sodium dif...
Scheme 25: Photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamides with S-(difluoromethyl)su...
Scheme 26: Proposed mechanism for the photoredox-catalyzed radical aryldifluoromethylation of N-arylacrylamide...
Scheme 27: Visible-light-induced domino difluoroalkylation/cyclization of N-cyanamide alkenes.
Scheme 28: Proposed mechanism of photoredox-catalyzed radical domino difluoroalkylation/cyclization of N-cyana...
Scheme 29: Palladium-catalyzed oxidative difunctionalization of alkenes.
Scheme 30: Two possible mechanisms of palladium-catalyzed oxidative difunctionalization.
Scheme 31: Silver-catalyzed oxidative 1,2-alkyletherification of unactivated alkenes with α-bromoalkylcarbonyl...
Scheme 32: Photochemical radical cascade cyclization of dienes.
Scheme 33: Proposed mechanism for the photochemical radical cascade 6-endo cyclization of dienes with α-carbon...
Scheme 34: Photocatalyzed radical coupling/cyclization of N-arylacrylamides and.
Scheme 35: Photocatalyzed radical-type couplings/cyclization of N-arylacrylamides with sulfoxonium ylides.
Scheme 36: Possible mechanism of visible-light-induced radical-type couplings/cyclization of N-arylacrylamides...
Scheme 37: Visible-light-promoted difluoroalkylated oxindoles systhesis via EDA complexes.
Scheme 38: Possible mechanism for the visible-light-promoted radical cyclization of N-arylacrylamides with bro...
Scheme 39: A dicumyl peroxide-initiated radical cascade reaction of N-arylacrylamide with DCM.
Scheme 40: Possible mechanism of radical cyclization of N-arylacrylamides with DCM.
Scheme 41: An AIBN-mediated radical cascade reaction of N-arylacrylamides with perfluoroalkyl iodides.
Scheme 42: Possible mechanism for the reaction with perfluoroalkyl iodides.
Scheme 43: Photoinduced palladium-catalyzed radical annulation of N-arylacrylamides with alkyl halides.
Scheme 44: Radical alkylation/cyclization of N-Alkyl-N-methacryloylbenzamides with alkyl halides.
Scheme 45: Possible mechanism for the alkylation/cyclization with unactivated alkyl chlorides.
Scheme 46: Visible-light-driven palladium-catalyzed radical cascade cyclization of N-arylacrylamides with unac...
Scheme 47: NHC-catalyzed radical cascade cyclization of N-arylacrylamides with alkyl bromides.
Scheme 48: Possible mechanism of NHC-catalyzed radical cascade cyclization.
Scheme 49: Electrochemically mediated radical cyclization reaction of N-arylacrylamides with freon-type methan...
Scheme 50: Proposed mechanistic pathway of electrochemically induced radical cyclization reaction.
Scheme 51: Redox-neutral photoinduced radical cascade cylization of N-arylacrylamides with unactivated alkyl c...
Scheme 52: Proposed mechanistic hypothesis of redox-neutral radical cascade cyclization.
Scheme 53: Thiol-mediated photochemical radical cascade cylization of N-arylacrylamides with aryl halides.
Scheme 54: Proposed possible mechanism of thiol-mediated photochemical radical cascade cyclization.
Scheme 55: Visible-light-induced radical cascade bromocyclization of N-arylacrylamides with NBS.
Scheme 56: Possible mechanism of visible-light-induced radical cascade cyclization.
Scheme 57: Decarboxylation/radical C–H functionalization by visible-light photoredox catalysis.
Scheme 58: Plausible mechanism of visible-light photoredox-catalyzed radical cascade cyclization.
Scheme 59: Visible-light-promoted tandem radical cyclization of N-arylacrylamides with N-(acyloxy)phthalimides....
Scheme 60: Plausible mechanism for the tandem radical cyclization reaction.
Scheme 61: Visible-light-induced aerobic radical cascade alkylation/cyclization of N-arylacrylamides with alde...
Scheme 62: Plausible mechanism for the aerobic radical alkylarylation of electron-deficient amides.
Scheme 63: Oxidative decarbonylative [3 + 2]/[5 + 2] annulation of N-arylacrylamide with vinyl acids.
Scheme 64: Plausible mechanism for the decarboxylative (3 + 2)/(5 + 2) annulation between N-arylacrylamides an...
Scheme 65: Rhenium-catalyzed alkylarylation of alkenes with PhI(O2CR)2.
Scheme 66: Plausible mechanism for the rhenium-catalyzed decarboxylative annulation of N-arylacrylamides with ...
Scheme 67: Visible-light-induced one-pot tandem reaction of N-arylacrylamides.
Scheme 68: Plausible mechanism for the visible-light-initiated tandem synthesis of difluoromethylated oxindole...
Scheme 69: Copper-catalyzed redox-neutral cyanoalkylarylation of activated alkenes with cyclobutanone oxime es...
Scheme 70: Plausible mechanism for the copper-catalyzed cyanoalkylarylation of activated alkenes.
Scheme 71: Photoinduced alkyl/aryl radical cascade for the synthesis of quaternary CF3-attached oxindoles.
Scheme 72: Plausible photoinduced electron-transfer (PET) mechanism.
Scheme 73: Photoinduced cerium-mediated decarboxylative alkylation cascade cyclization.
Scheme 74: Plausible reaction mechanism for the decarboxylative radical-cascade alkylation/cyclization.
Scheme 75: Metal-free oxidative tandem coupling of activated alkenes.
Scheme 76: Control experiments and possible mechanism for 1,2-carbonylarylation of alkenes with carbonyl C(sp2...
Scheme 77: Silver-catalyzed acyl-arylation of activated alkenes with α-oxocarboxylic acids.
Scheme 78: Proposed mechanism for the decarboxylative acylarylation of acrylamides.
Scheme 79: Visible-light-mediated tandem acylarylation of olefines with carboxylic acids.
Scheme 80: Proposed mechanism for the radical cascade cyclization with acyl radical via visible-light photored...
Scheme 81: Erythrosine B-catalyzed visible-light photoredox arylation-cyclization of N-arylacrylamides with ar...
Scheme 82: Electrochemical cobalt-catalyzed radical cyclization of N-arylacrylamides with arylhydrazines or po...
Scheme 83: Proposed mechanism of radical cascade cyclization via electrochemical cobalt catalysis.
Scheme 84: Copper-catalyzed oxidative tandem carbamoylation/cyclization of N-arylacrylamides with hydrazinecar...
Scheme 85: Proposed reaction mechanism for the radical cascade cyclization by copper catalysis.
Scheme 86: Visible-light-driven radical cascade cyclization reaction of N-arylacrylamides with α-keto acids.
Scheme 87: Proposed mechanism of visible-light-driven cascade cyclization reaction.
Scheme 88: Peroxide-induced radical carbonylation of N-(2-methylallyl)benzamides with methyl formate.
Scheme 89: Proposed cyclization mechanism of peroxide-induced radical carbonylation with N-(2-methylallyl)benz...
Scheme 90: Persulfate promoted carbamoylation of N-arylacrylamides and N-arylcinnamamides.
Scheme 91: Proposed mechanism for the persulfate promoted radical cascade cyclization reaction of N-arylacryla...
Scheme 92: Photocatalyzed carboacylation with N-arylpropiolamides/N-alkyl acrylamides.
Scheme 93: Plausible mechanism for the photoinduced carboacylation of N-arylpropiolamides/N-alkyl acrylamides.
Scheme 94: Electrochemical Fe-catalyzed radical cyclization with N-arylacrylamides.
Scheme 95: Plausible mechanism for the electrochemical Fe-catalysed radical cyclization of N-phenylacrylamide.
Scheme 96: Substrate scope of the selective functionalization of various α-ketoalkylsilyl peroxides with metha...
Scheme 97: Proposed reaction mechanism for the Fe-catalyzed reaction of alkylsilyl peroxides with methacrylami...
Scheme 98: EDA-complex mediated C(sp2)–C(sp3) cross-coupling of TTs and N-methyl-N-phenylmethacrylamides.
Scheme 99: Proposed mechanism for the synthesis of oxindoles via EDA complex.
Recent advances in synthetic approaches for bioactive cinnamic acid derivatives
- Betty A. Kustiana,
- Galuh Widiyarti and
- Teni Ernawati
Beilstein J. Org. Chem. 2025, 21, 1031–1086, doi:10.3762/bjoc.21.85
Graphical Abstract
Figure 1: Biologically active cinnamic acid derivatives.
Scheme 1: General synthetic strategies for cinnamic acid derivatizations.
Scheme 2: Cinnamic acid coupling via isobutyl anhydride formation.
Scheme 3: Amidation reaction via O/N-pivaloyl activation.
Scheme 4: Cinnamic acid amidation using TCCA/PPh3 reagent.
Scheme 5: Cinnamic acid amidation using triazine-based reagents.
Scheme 6: Cinnamic acid amidation using continuous flow mechanochemistry.
Scheme 7: Cinnamic acid amidation using COMU as coupling reagent.
Scheme 8: Cinnamic acid amidation using allenone coupling reagent.
Scheme 9: Cinnamic acid amidation using 4-acetamidophenyl triflimide as reagent.
Scheme 10: Cinnamic acid amidation using methyltrimethoxysilane (MTM).
Scheme 11: Cinnamic acid amidation utilizing amine–borane reagent.
Scheme 12: Cinnamic acid amidation using TCCA/PPh3 reagent.
Scheme 13: Cinnamic acid amidation using PPh3/I2 reagent.
Scheme 14: Cinnamic acid amidation using PCl3 reagent.
Scheme 15: Cinnamic acid amidation utilizing pentafluoropyridine (PFP) as reagent.
Scheme 16: Cinnamic acid amidation using hypervalent iodine(III).
Scheme 17: Mechanochemical amidation using 1,1,2,2-tetrafluoroethyl-N,N-dimethylamine (TFEDMA) reagent.
Scheme 18: Methyl ester preparation using tris(2,4,6-trimethoxyphenyl)phosphine (TMPP).
Scheme 19: N-Trifluoromethyl amide preparation using isothiocyanate and AgF.
Scheme 20: POCl3-mediated amide coupling of carboxylic acid and DMF.
Scheme 21: O-Alkylation of cinnamic acid using alkylating agents.
Scheme 22: Glycoside preparation via Mitsunobu reaction.
Scheme 23: O/N-Acylation via rearrangement reactions.
Scheme 24: Amidation reactions using sulfur-based alkylating agents.
Scheme 25: Amidation reaction catalyzed by Pd0 via C–N cleavage.
Scheme 26: Amidation reaction catalyzed by CuCl/PPh3.
Scheme 27: Cu(II) triflate-catalyzed N-difluoroethylimide synthesis.
Scheme 28: Cu/Selectfluor-catalyzed transamidation reaction.
Scheme 29: CuO–CaCO3-catalyzed amidation reaction.
Scheme 30: Ni-catalyzed reductive amidation.
Scheme 31: Lewis acidic transition-metal-catalyzed O/N-acylations.
Scheme 32: Visible-light-promoted amidation of cinnamic acid.
Scheme 33: Sunlight/LED-promoted amidation of cinnamic acid.
Scheme 34: Organophotocatalyst-promoted N–O cleavage of Weinreb amides to synthesize primary amides.
Scheme 35: Cinnamamide synthesis through [Ir] photocatalyst-promoted C–N-bond cleavage of tertiary amines.
Scheme 36: Blue LED-promoted FeCl3-catalyzed reductive transamidation.
Scheme 37: FPyr/TCT-catalyzed amidation of cinnamic acid derivative 121.
Scheme 38: Cs2CO3/DMAP-mediated esterification.
Scheme 39: HBTM organocatalyzed atroposelective N-acylation.
Scheme 40: BH3-catalyzed N-acylation reactions.
Scheme 41: Borane-catalyzed N-acylation reactions.
Scheme 42: Catalytic N-acylation reactions via H/F bonding activation.
Scheme 43: Brønsted base-catalyzed synthesis of cinnamic acid esters.
Scheme 44: DABCO/Fe3O4-catalyzed N-methyl amidation of cinnamic acid 122.
Scheme 45: Catalytic oxidation reactions of acylating agents.
Scheme 46: Preparation of cinnamamide-substituted benzocyclooctene using I(I)/I(III) catalysis.
Scheme 47: Pd-colloids-catalyzed oxidative esterification of cinnamyl alcohol.
Scheme 48: Graphene-supported Pd/Au alloy-catalyzed oxidative esterification via hemiacetal intermediate.
Scheme 49: Au-supported on A) carbon nanotubes (CNT) and B) on porous boron nitride (pBN) as catalyst for the ...
Scheme 50: Cr-based catalyzed oxidative esterification of cinnamyl alcohols with H2O2 as the oxidant.
Scheme 51: Co-based catalysts used for oxidative esterification of cinnamyl alcohol.
Scheme 52: Iron (A) and copper (B)-catalyzed oxidative esterification of cinnamaldehyde.
Scheme 53: NiHPMA-catalyzed oxidative esterification of cinnamaldehyde.
Scheme 54: Synthesis of cinammic acid esters through NHC-catalyzed oxidative esterification via intermolecular...
Scheme 55: Redox-active NHC-catalyzed esterification via intramolecular oxidation.
Scheme 56: Electrochemical conversion of cinnamaldehyde to methyl cinnamate.
Scheme 57: Bu4NI/TBHP-catalyzed synthesis of bisamides from cinnamalaldehyde N-tosylhydrazone.
Scheme 58: Zn/NC-950-catalyzed oxidative esterification of ketone 182.
Scheme 59: Ru-catalyzed oxidative carboxylation of terminal alkenes.
Scheme 60: Direct carboxylation of alkenes using CO2.
Scheme 61: Carboxylation of alkenylboronic acid/ester.
Scheme 62: Carboxylation of gem-difluoroalkenes with CO2.
Scheme 63: Photoredox-catalyzed carboxylation of difluoroalkenes.
Scheme 64: Ru-catalyzed carboxylation of alkenyl halide.
Scheme 65: Carboxylation of alkenyl halides under flow conditions.
Scheme 66: Cinnamic acid ester syntheses through carboxylation of alkenyl sulfides/sulfones.
Scheme 67: Cinnamic acid derivatives synthesis through a Ag-catalyzed decarboxylative cross-coupling proceedin...
Scheme 68: Pd-catalyzed alkyne hydrocarbonylation.
Scheme 69: Fe-catalyzed alkyne hydrocarbonylation.
Scheme 70: Alkyne hydrocarboxylation using CO2.
Scheme 71: Alkyne hydrocarboxylation using HCO2H as CO surrogate.
Scheme 72: Co/AlMe3-catalyzed alkyne hydrocarboxylation using DMF.
Scheme 73: Au-catalyzed oxidation of Au–allenylidenes.
Scheme 74: Pd-catalyzed C–C-bond activation of cyclopropenones to synthesize unsaturated esters and amides.
Scheme 75: Ag-catalyzed C–C-bond activation of diphenylcyclopropenone.
Scheme 76: Cu-catalyzed C–C bond activation of diphenylcyclopropenone.
Scheme 77: PPh3-catalyzed C–C-bond activation of diphenylcyclopropenone.
Scheme 78: Catalyst-free C–C-bond activation of diphenylcyclopropenone.
Scheme 79: Cu-catalyzed dioxolane cleavage.
Scheme 80: Multicomponent coupling reactions.
Scheme 81: Pd-catalyzed partial hydrogenation of electrophilic alkynes.
Scheme 82: Nickel and cobalt as earth-abundant transition metals used as catalysts for the partial hydrogenati...
Scheme 83: Metal-free-catalyzed partial hydrogenation of conjugated alkynes.
Scheme 84: Horner–Wadsworth–Emmons reaction between triethyl 2-fluoro-2-phosphonoacetate and aldehydes with ei...
Scheme 85: Preparation of E/Z-cinnamates using thiouronium ylides.
Scheme 86: Transition-metal-catalyzed ylide reactions.
Scheme 87: Redox-driven ylide reactions.
Scheme 88: Noble transition-metal-catalyzed olefination via carbenoid species.
Scheme 89: TrBF4-catalyzed olefination via carbene species.
Scheme 90: Grubbs catalyst (cat 7)/photocatalyst-mediated metathesis reactions.
Scheme 91: Elemental I2-catalyzed carbonyl-olefin metathesis.
Scheme 92: Cu-photocatalyzed E-to-Z isomerization of cinnamic acid derivatives.
Scheme 93: Ni-catalyzed E-to-Z isomerization.
Scheme 94: Dehydration of β-hydroxy esters via an E1cB mechanism to access (E)-cinnamic acid esters.
Scheme 95: Domino ring-opening reaction induced by a base.
Scheme 96: Dehydroamination of α-aminoester derivatives.
Scheme 97: Accessing methyl cinnamate (44) via metal-free deamination or decarboxylation.
Scheme 98: The core–shell magnetic nanosupport-catalyzed condensation reaction.
Scheme 99: Accessing cinnamic acid derivatives from acetic acid esters/amides through α-olefination.
Scheme 100: Accessing cinnamic acid derivatives via acceptorless α,β-dehydrogenation.
Scheme 101: Cu-catalyzed formal [3 + 2] cycloaddition.
Scheme 102: Pd-catalyzed C–C bond formation via 1,4-Pd-shift.
Scheme 103: NHC-catalyzed Rauhut–Currier reactions.
Scheme 104: Heck-type reaction for Cα arylation.
Scheme 105: Cu-catalyzed trifluoromethylation of cinnamamide.
Scheme 106: Ru-catalyzed alkenylation of arenes using directing groups.
Scheme 107: Earth-abundant transition-metal-catalyzed hydroarylation of α,β-alkynyl ester 374.
Scheme 108: Precious transition-metal-catalyzed β-arylation of cinnamic acid amide/ester.
Scheme 109: Pd-catalyzed β-amination of cinnamamide.
Scheme 110: S8-mediated β-amination of methyl cinnamate (44).
Scheme 111: Pd-catalyzed cross-coupling reaction of alkynyl esters with phenylsilanes.
Scheme 112: Pd-catalyzed β-cyanation of alkynyl amide/ester.
Scheme 113: Au-catalyzed β-amination of alkynyl ester 374.
Scheme 114: Metal-free-catalyzed Cβ-functionalizations of alkynyl esters.
Scheme 115: Heck-type reactions.
Scheme 116: Mizoroki–Heck coupling reactions using unconventional functionalized arenes.
Scheme 117: Functional group-directed Mizoroki–Heck coupling reactions.
Scheme 118: Pd nanoparticles-catalyzed Mizoroki–Heck coupling reactions.
Scheme 119: Catellani-type reactions to access methyl cinnamate with multifunctionalized arene.
Scheme 120: Multicomponent coupling reactions.
Scheme 121: Single atom Pt-catalyzed Heck coupling reaction.
Scheme 122: Earth-abundant transition metal-catalyzed Heck coupling reactions.
Scheme 123: Polymer-coated earth-abundant transition metals-catalyzed Heck coupling reactions.
Scheme 124: Earth-abundant transition-metal-based nanoparticles as catalysts for Heck coupling reactions.
Scheme 125: CN- and Si-based directing groups to access o-selective cinnamic acid derivatives.
Scheme 126: Amide-based directing group to access o-selective cinnamic acid derivatives.
Scheme 127: Carbonyl-based directing group to access o-selective cinnamic acid derivatives.
Scheme 128: Stereoselective preparation of atropisomers via o-selective C(sp2)–H functionalization.
Scheme 129: meta-Selective C(sp2)–H functionalization using directing group-tethered arenes.
Scheme 130: para-Selective C(sp2)–H functionalization using directing group-tethered arenes.
Scheme 131: Non-directed C(sp2)–H functionalization via electrooxidative Fujiwara–Moritani reaction.
Scheme 132: Interconversion of functional groups attached to cinnamic acid.
Scheme 133: meta-Selective C(sp2)–H functionalization of cinnamate ester.
Scheme 134: C(sp2)–F arylation using Grignard reagents.
Scheme 135: Truce–Smiles rearrangement of N-aryl metacrylamides.
Scheme 136: Phosphine-catalyzed cyclization of γ-vinyl allenoate with enamino esters.
Formaldehyde surrogates in multicomponent reactions
- Cecilia I. Attorresi,
- Javier A. Ramírez and
- Bernhard Westermann
Beilstein J. Org. Chem. 2025, 21, 564–595, doi:10.3762/bjoc.21.45
Graphical Abstract
Scheme 1: Features of the ideal reaction (redrawn from P. A. Wender et al. [1]).
Scheme 2: Some of the most popular MCRs with formaldehyde as the carbonyl component.
Scheme 3: Ugi reaction under a catalyzed electro-oxidation process using TEMPO (2,2,6,6-tetramethyl-1-piperid...
Scheme 4: Examples of different products obtained by MCRs in which DMSO serves as -SCH3 source.
Scheme 5: Mechanism of the decomposition of DMSO under acidic or thermal conditions. a) In situ generation of...
Scheme 6: Povarov multicomponent reaction to quinolines.
Scheme 7: Example of the Povarov reaction with formaldehyde with a julolidine derivative as main product.
Scheme 8: Povarov multicomponent reaction to quinoline derivatives I and II using DMSO as formaldehyde surrog...
Scheme 9: Example of a Povarov three-component reaction with change of catalyst, yielding regioisomer III. In...
Scheme 10: The Povarov three-component reactions carried out under acidic catalysis to afford quinoline regios...
Scheme 11: Different MCR routes involving DMSO to synthesize complex heterocycles such as diarylpyridines and ...
Scheme 12: Pyrazole synthesis by a three-component reaction using DMSO as a source of a C-1 unit.
Scheme 13: Three-component reactions for the synthesis of aliphatic heterocycles 13 and 14 using DMSO as a for...
Scheme 14: Proposed mechanism for the 3CR between homoallylic amines, disulfides, and DMSO.
Scheme 15: Mannich-type reaction using DMSO as formaldehyde surrogate.
Scheme 16: Mechanism for the 3CR-Mannich-type reaction between aryl ketone 18, saccharine (19), and DMSO. The ...
Scheme 17: Mannich-type reaction using DMSO as formaldehyde surrogate and under oxidative activation.
Scheme 18: Three-component reaction between an indazole, a carboxylic acid, and DMSO.
Scheme 19: Amine–aldehyde–alkyne (AAA) coupling reaction and plausible mechanism.
Scheme 20: AHA coupling for the synthesis of propargylamines using dihalomethanes as C1 building blocks.
Scheme 21: AHA coupling using CH2Cl2 as both solvent and methylene source.
Scheme 22: Examples of propargylamines synthesized under catalytic AHA protocols.
Scheme 23: Proposed mechanism for the synthesis of propargylamines using dichloromethane as a C1 source.
Scheme 24: Mechanism proposed for the generation of the aminal intermediate E by Buckley et al. [68].
Scheme 25: Pudovic and Kabachnik–Fields reactions for the synthesis of α-aminophosphonates.
Scheme 26: a) Abramov side reaction that generates α-hydroxy phosphonate as a byproduct during the Kabachnik-F...
Scheme 27: Catalyst-free three component reaction to afford α-amino phosphorus product 35 using 1,1-dihaloalka...
Scheme 28: a) Proposed mechanism for the three-component reaction of dichloromethane, amine and phosphorus com...
Scheme 29: Ugi-ammonia strategy using HMTA as a formaldehyde surrogate.
Scheme 30: Glyoxylate and its derivatives as C1 building blocks.
Scheme 31: The Groebke–Blackburn–Bienaymé multicomponent reaction (GBB) and its mechanism.
Scheme 32: a) Byproducts in the GBB multicomponent reaction (GBB) when formaldehyde is used as the carbonyl co...
Scheme 33: Possible regioisomers in the GBB multicomponent reaction when formaldehyde is used as the carbonyl ...
Scheme 34: The multicomponent GBB reaction yields 2-unsubstituted 3-aminoimidazo heterocycles 42a using MP-gly...
Scheme 35: GBB multicomponent reaction to 2-unsubstituted 3-amino imidazo heterocycles 42a using glyoxylic aci...
Scheme 36: GBB reaction using glyoxylic acid immobilized on silica as formaldehyde surrogate.
Scheme 37: Bioactive products synthesized by the GBB reaction using glyoxylic acid.
Scheme 38: van Leusen three-component reaction to imidazoles.
Scheme 39: Side reaction during the synthesis of imidazoles with formaldehyde as the carbonyl compound.
Scheme 40: Optimization of the van Leusen three component reaction to 1,4-disubstituted imidazoles 43 using gl...
Scheme 41: Application of the Sisko strategy [96] for the synthesis of CB1 receptor antagonist compounds [97].
Scheme 42: Side reaction, when NH4OH is used as amine component.
Scheme 43: Ugi-type adducts with the ester moiety and the acidic CH to be used for post-cyclization sequences.
Scheme 44: Ugi/cycloisomerization process to pyrrolones 51, butenolides 52, and pyrroline 53.
Scheme 45: Radical cyclization reactions from Ugi adducts promoted by TEMPO.
Scheme 46: Hydrolysis and decarboxylation reactions to products with incorporation of a C1 unit of ethyl glyox...
Scheme 47: One-step synthetic route to pyrrolones 60 using phenylglyoxal.
Scheme 48: Ugi-pseudo-Knoevenagel-pseudo-Dieckmann cascade sequence for the synthesis of fused heterocycles.
Scheme 49: Ugi-pseudo-Knoevenagel reaction from ethyl glyoxylate.
Synthesis, structure, ionochromic and cytotoxic properties of new 2-(indolin-2-yl)-1,3-tropolones
- Yurii A. Sayapin,
- Eugeny A. Gusakov,
- Inna O. Tupaeva,
- Alexander D. Dubonosov,
- Igor V. Dorogan,
- Valery V. Tkachev,
- Anna S. Goncharova,
- Gennady V. Shilov,
- Natalia S. Kuznetsova,
- Svetlana Y. Filippova,
- Tatyana A. Krasnikova,
- Yanis A. Boumber,
- Alexey Y. Maksimov,
- Sergey M. Aldoshin and
- Vladimir I. Minkin
Beilstein J. Org. Chem. 2025, 21, 358–368, doi:10.3762/bjoc.21.26
- interaction of 2,3,3-trimethylindolenine with 3,5-di(tert-butyl)-1,2-benzoquinone leads to the formation of indolo[1,2-a]indoline derivatives [23], while the presence of a nitro group in 4,6-di(tert-butyl)-3-nitro-1,2-benzoquinone the reaction with 2,3,3-trimethylindolenine leads to an o-quinone ring
- tropolone ring proton, which appears at 6.9 ppm. A characteristic specificity of the 1H NMR spectra of compounds 7 and 8 is the presence of signals of hydroxy group protons forming a strong hydrogen bond with the indoline nitrogen atom, which closes the six-membered chelate cycle. These signals are observed
Graphical Abstract
Scheme 1: Synthesis of 2-hetaryl-substituted 1,3-tropolones 1.
Scheme 2: Synthesis of 1,3-tropolones 7a,b and 8a,b. Reagents and conditions: method A: dioxane, reflux; meth...
Figure 1: Structural characteristics of (NH) and (OH) tautomeric forms of compounds 7 and 8 in the gas phase ...
Figure 2: Scheme of HMBC correlations of compound 7a in DMSO-d6.
Figure 3: Molecular structure of 2-(3,3-dimethyl-3H-benzo[g]indolin-2-yl)-5,6,7-trichloro-1,3-tropolone (7b).
Figure 4: Result of matching structures of 7b (solid lines) and 2-(3,3-dimethylindolin-2-yl)-5,6,7-trichloro-...
Figure 5: Absorption and emission spectra of compound 8b in acetonitrile before (1,1’) (c 2.5 × 10−5 mol L–1)...
Scheme 3: Possible binding mode of 7 and 8 with CN− and F−.
Figure 6: Dose–response curves for H1299 and A431 cells treated with compound 7a for 24 h. *Significant diffe...
Molecular diversity of the reactions of MBH carbonates of isatins and various nucleophiles
- Zi-Ying Xiao,
- Jing Sun and
- Chao-Guo Yan
Beilstein J. Org. Chem. 2025, 21, 286–295, doi:10.3762/bjoc.21.21
- diastereomeric ratios. The relative configurations of the various polycyclic compounds were clearly elucidated by determination of several single crystal structures. Keywords: allylic SN2 reaction; dimerization; isatin; MBH carbonate; 3-methyleneoxindole; Introduction Isatins (indoline-2,3-diones) possessing
Graphical Abstract
Scheme 1: Reaction of arylamines and MBH carbonates of isatins. Reaction conditions: MBH carbonate of isatin ...
Scheme 2: Reaction of arylamines and MBH maleimides of isatins. Reaction conditions: MBH maleimide of isatin ...
Figure 1: Single crystal structure of compound 5a.
Figure 2: Single crystal structure of compound 5j.
Scheme 3: Reactions of MBH carbonates of isatins and triphenylphosphine. Reaction conditions: MBH carbonate o...
Figure 3: Single crystal structure of compound 6e.
Figure 4: Single crystal structure of compound 7a.
Figure 5: Single crystal structure of compound 8a.
Scheme 4: Proposed reaction mechanism for the various compounds.
N-Glycosides of indigo, indirubin, and isoindigo: blue, red, and yellow sugars and their cancerostatic activity
- Peter Langer
Beilstein J. Org. Chem. 2024, 20, 2840–2869, doi:10.3762/bjoc.20.240
- -glycosides containing the carbohydrate moiety located at the amine-type nitrogen atom (Scheme 18) [25]. For this purpose, we decided to react isatins with N-glycosylated indoxyls which were entirely unknown at that time. The reaction of ʟ-rhamnose α/β-4c with indoline afforded α/β-25a (β:α ≈ 4:1
- -glycosides Sassatelli et al. reported the synthesis of isoindigo-N-glycosides β-57a–c by reaction of benzyl-protected isatin-N-glycosides β-56a–c with oxindole (55) (Scheme 35) [53][54][55]. Deprotection by BBr3 afforded β-58a–c. Isatins 56 were prepared by glycosylation of indoline, benzylation, and
- of rhamnose with indoline (66) afforded β-67a which was transformed to indol-N-rhamnoside β-68a (Scheme 39) [59]. Benzylation and subsequent oxidation gave isatin-N-rhamnoside β-70a, albeit, in low yield. Condensation with 2-coumaranone (63) afforded the benzylated oxoisoindigo-N-rhamnoside β-71a
Graphical Abstract
Scheme 1: Structures of indigo (1a), indirubin (2a) and isoindigo (3a).
Scheme 2: Structures of akashins A–C.
Scheme 3: Synthesis of 5b. Reagents and conditions: i) TMSOTf, 4 Å MS, CH2Cl2, −20 °C, 1.5 h, then 20 °C, 8–1...
Scheme 4: Synthesis of 7c. Reagents and conditions: i) TMSOTf, 4 Å MS, CH2Cl2, −18 °C, 3 h; then: TMSOTf, 4 Å...
Scheme 5: Synthesis of 1d. Reagents and conditions: i) chloroacetic acid, Na2CO3, reflux, 6 h; ii) Ac2O, NaOA...
Scheme 6: Synthesis of 10e. Reagents and conditions: i) p-TsOH·H2O, acetonitrile, MeOH, 1 d; ii) NIS, PPh3, D...
Scheme 7: Synthesis of akashins A–C. Reagents and conditions: i) TMSOTf, 4 Å MS, CH2Cl2, −18 to 20 °C, 15 h; ...
Scheme 8: Synthesis of 5d. Reagents and conditions: i) KMnO4, AcOH, high-power-stirring (12.000 rot/min), 20 ...
Scheme 9: Possible mechanism of the formation of 5c.
Scheme 10: Synthesis of 7d. Reagents and conditions: i) 1) CH2Cl2, 2) Me3SiI, 20 °C, 30 min, 3) 0 °C, 30 min, ...
Scheme 11: Synthesis of α-15b. Reagents and conditions: i) 1) CH2Cl2, 2) Me3SiI, 20 °C, 30 min, 3) 0 °C, 30 mi...
Scheme 12: Synthesis of isatin-N-glycosides 16a–f. Reagents and conditions: i) PhNH2, EtOH, 20 °C, 12 h; ii) Ac...
Scheme 13: Synthesis of 17–21. Reagents and conditions: i) Na2CO3, MeOH, 20 °C, 4 h.
Scheme 14: Synthesis of indirubin-N-glycosides α-17a and α-17b.
Scheme 15: Synthesis of β-17f. Reagents and conditions: i) 1) Na2CO3, MeOH, 20 °C, 4 h, 2) Ac2O/pyridine 1:1, ...
Scheme 16: Synthesis of β-24a. Reagents and conditions: i) n-PrOH, H2O, formic acid (buffer, 100 mM), 2 h, 65 ...
Scheme 17: Synthesis of isatin-N-glycosides 23b–g and 24b–g.
Scheme 18: Synthesis of β-29a,b. Reagents and conditions: i) EtOH, 20 °C, 12 h; ii) DDQ, dioxane, 20 °C, 12 h;...
Scheme 19: Synthesis of β-31a. Reagents and conditions: i) Na2SO3, dioxane, H2O, 110 °C, 2 d; ii) piperidine, ...
Scheme 20: Synthesis of 33a–d. Reagents and conditions: i) Ac2O, AcOH, NaOAc, 80 °C, 1 h; ii) 1) NaOMe, anhydr...
Scheme 21: Indirubins 34 and 35.
Scheme 22: Synthesis of 36f. Reagents and conditions: i) NaOH, H2O, 20 °C, 5 h; ii) HCl, NaNO2, H2O, −14 °C; i...
Scheme 23: Synthesis of 38a–h. Reagents and conditions: i) 1) 0.1 equiv NaOMe, MeOH, 20 °C, 15–20 min, 2) HOAc...
Scheme 24: Synthesis of 40a–h. Reagents and conditions: i) method A: EtOH/THF, cat. KOt-Bu, 20 °C, 3–4.5 h; me...
Scheme 25: Synthesis of 41a–d. Reagents and conditions: i) Ac2O, AcOH, NaOAc, 80 °C, 1 h.
Scheme 26: Synthesis of 41e. Reagents and conditions: i) AcOH, NaOAc, 110 °C, 24 h.
Scheme 27: Synthesis of E-β-43a–e and E-β-44a,b. Reagents and conditions: i) 1) NEt3, EtOH, 20 °C, 12 h, 2) DM...
Scheme 28: Synthesis of E-43f. Reagents and conditions: i) Na2CO3, MeOH, 20 °C, 6–24 h.
Scheme 29: Synthesis of 46a–m. Reagents and conditions: i) NEt3 (1 equiv), EtOH, 20 °C, 6–10 h; ii) MsCl, NEt3...
Scheme 30: Synthesis of 48a–d. Reagents and conditions: i) AcOH/Ac2O, NaOAc, 60 °C, 3–4 h.
Scheme 31: Synthesis of 48e. Reagents and conditions: i) NaOAc, AcOH, 110 °C, 24 h.
Scheme 32: Synthesis of β-49a,b. Reagents and conditions: i) AcOH/Ac2O, NaOAc, 60 °C, 3–4 h.
Scheme 33: Synthesis of β-54a,b. Reagents and conditions: i) 1) NaH, DMF, 0 °C, 15 min, 2) β-51a,b, 20 °C, 3 h...
Scheme 34: Synthesis of 54c–l. The yields refer to the yields of the first and second condensation step for ea...
Scheme 35: Synthesis of 57a–c and 58a–d. Reagents and conditions: i) HCl (conc.), AcOH, reflux, 24 h; ii) 1) B...
Scheme 36: Synthesis of 59a–e and 60a–e. Reagents and conditions: i) P(NEt2)3 (1.1 equiv), CH2Cl2, −78 °C to 2...
Scheme 37: Synthesis of 61a–d and 62a–d. Reagents and conditions: i) P(NEt2)3 (1.1 equiv), CH2Cl2, −78 °C to 2...
Scheme 38: Synthesis of β-64a–e and α-64a. Reagents and conditions: i) AcOH, Ac2O, NaOAc, 90 °C, 6 h.
Scheme 39: Synthesis of β-72a. Reagents and conditions: i) 66, EtOH, 20 °C, 12 h; ii) DDQ, dioxane, 20 °C, 12 ...
Scheme 40: Synthesis of β-72b.
Scheme 41: Synthesis of β-74a–c. Reagents and conditions: i) AcOH, Ac2O, NaOAc, 130 °C, 2 d.
Scheme 42: Synthesis of β-77. Reagents and conditions: i) 1) NEt3, EtOH, 20 °C, 12 h, 2) DMAP, NEt3, MsCl, 0 °...
Scheme 43: Synthesis of β-81a–f and β-80g. Reagents and conditions: i) AcOH, 80 °C, 1–3 h; ii) benzene, PTSA, ...
Scheme 44: Synthesis of 84a. Reagents and conditions: i) benzene, AlCl3, 20 °C, 10 min; ii) MeOH, NaOMe, 12 h,...
Scheme 45: Synthesis of 84b–l. The yields refer to the yields of the condensation and the deprotection step fo...
Synthesis of spiroindolenines through a one-pot multistep process mediated by visible light
- Francesco Gambuti,
- Jacopo Pizzorno,
- Chiara Lambruschini,
- Renata Riva and
- Lisa Moni
Beilstein J. Org. Chem. 2024, 20, 2722–2731, doi:10.3762/bjoc.20.230
- cyclization of the indole derivatives is the most popular (Scheme 1a). For instance, the efficient synthesis of spiro[indoline-3,2′-pyrrolidines] [8][9][10] or spiro-isoxazoles [11] through different dearomatization processes has been reported. Recently, Ramana and Dothe have proposed an elegant gold
Graphical Abstract
Figure 1: Selected natural products containing spiro-indolenines.
Scheme 1: Synthesis of spiro[indole-heterocycles].
Scheme 2: Synthetic strategy for the new synthesis of 2,3-diaminoindolenines [21] and spiro[indole-isoquinolines]....
Scheme 3: Scope of the synthesis of spiro[indole-THIQs]. aα-aminoamidine 2b has been isolated (54%) too; bα-a...
Scheme 4: Two-step synthesis using p-methylaniline.
Scheme 5: Investigation of the one-pot four-step synthetic protocol employing N-Ph-benzoxazepine 5.
Figure 2: Time profile of the reaction of N-Ph-THIQ, 3,5-dimethoxyaniline and t-BuNC conducted under optimize...
Scheme 6: Proposed mechanism.
Hypervalent iodine-mediated cyclization of bishomoallylamides to prolinols
- Smaher E. Butt,
- Konrad Kepski,
- Jean-Marc Sotiropoulos and
- Wesley J. Moran
Beilstein J. Org. Chem. 2024, 20, 2455–2460, doi:10.3762/bjoc.20.209
- yield (Scheme 1B). Notably, we are unaware of any reported method to achieve this specific transformation in the literature. Although, Tellitu and co-workers have reported a related preparation of indoline derivatives mediated by bis(trifluoroacetoxy)iodobenzene (PIFA) [17]. Results and Discussion In
Graphical Abstract
Figure 1: Functional molecules containing a substituted pyrrolidine core.
Scheme 1: A) Our previous report on N-alkenylamide cyclizations. B) An overview of the present work.
Scheme 2: Calculated mechanism for the cyclization of amide 3a optimized at the B3LYP/ 6-31+G(d,p) level of t...
Scheme 3: Scope of cyclization reaction.
Scheme 4: Reactions of di- and trisubstituted alkene substrates.
Supramolecular assemblies of amphiphilic donor–acceptor Stenhouse adducts as macroscopic soft scaffolds
- Ka-Lung Hung,
- Leong-Hung Cheung,
- Yikun Ren,
- Ming-Hin Chau,
- Yan-Yi Lam,
- Takashi Kajitani and
- Franco King-Chi Leung
Beilstein J. Org. Chem. 2024, 20, 1590–1603, doi:10.3762/bjoc.20.142
- design of the reported DAs, we designed and synthesized a series of DAs featuring a second-generation DASA switching motif and different chain lengths of the alkyl linker (i.e., DAn) that connects the DASA indoline motif with the hydrophilic part (i.e., the carboxylic acid motif, Scheme 1). The alkyl
- nitrogen atmosphere, followed by reduction of the indole motif in compound 1n to indoline in 2n. The ester group in compound 2n was deprotected under basic conditions to give compound 3n (Scheme 2). DAn with different chain lengths of the alkyl linker were synthesized through an aza-Piancatalli
Graphical Abstract
Scheme 1: Illustration of the reversible visible-light-controlled ring closure and thermal-driven ring-openin...
Scheme 2: Synthetic pathway to DAn.
Figure 1: UV–vis-absorption-spectral changes of DAn in THF solution (20 μM). (a) DA11, (c) DA7, (e) DA6 solut...
Figure 2: UV–vis absorption spectra of DAn in aqueous solution (43 μM). (a) DA11 (inset: enlarged 400–480 nm ...
Figure 3: TEM images of freshly prepared aqueous solutions before irradiation of (a) DA11 (0.25 wt %, 4.1 mM)...
Figure 4: Photograph of a freshly prepared aqueous DA11 solution (82.0 mM) ejected into a shallow pool of CaCl...
Figure 5: Photographs of macroscopic soft scaffolds prepared from aqueous solutions of (a) DA11 (32.9 mM), (c...
Figure 6: Macroscopic soft DAn scaffolds fabricated by the shear-flow method. Images taken during fluorescenc...
Manganese-catalyzed C–C and C–N bond formation with alcohols via borrowing hydrogen or hydrogen auto-transfer
- Mohd Farhan Ansari,
- Atul Kumar Maurya,
- Abhishek Kumar and
- Saravanakumar Elangovan
Beilstein J. Org. Chem. 2024, 20, 1111–1166, doi:10.3762/bjoc.20.98
- activated by the base dehydrogenates the alcohol to the aldehyde and indoline to indole by acceptorless dehydrogenation. Moreover, C3 alkylation proceeded via BH (Scheme 58). In early 2021, Maji’s group demonstrated an efficient approach for the C-alkylation of methyl N-heteroarenes with primary alcohols
Graphical Abstract
Scheme 1: General scheme of the borrowing hydrogen (BH) or hydrogen auto-transfer (HA) methodology.
Scheme 2: General scheme for C–N bond formation. A) Traditional cross-couplings with alkyl or aryl halides. B...
Figure 1: Manganese pre-catalysts used for the N-alkylation of amines with alcohols.
Scheme 3: Manganese(I)-pincer complex Mn1 used for the N-alkylation of amines with alcohols and methanol.
Scheme 4: N-Methylation of amines with methanol using Mn2.
Scheme 5: C–N-Bond formation with amines and methanol using PN3P-Mn complex Mn3 reported by Sortais et al. [36]. a...
Scheme 6: Base-assisted synthesis of amines and imines with Mn4. Reaction assisted by A) t-BuOK and B) t-BuON...
Scheme 7: Coupling of alcohols and hydrazine via the HB approach reported by Milstein et al. [38]. aReaction time...
Scheme 8: Proposed mechanism for the coupling of alcohols and hydrazine catalyzed by Mn5.
Scheme 9: Phosphine-free manganese catalyst for N-alkylation of amines with alcohols reported by Balaraman an...
Scheme 10: N-Alkylation of sulfonamides with alcohols.
Scheme 11: Mn–NHC catalyst Mn6 applied for the N-alkylation of amines with alcohols. a3 mol % of Mn6 were used....
Scheme 12: N-Alkylation of amines with primary and secondary alcohols. a80 °C, b100 °C.
Scheme 13: Manganese(III)-porphyrin catalyst for synthesis of tertiary amines.
Scheme 14: Proposed mechanism for the alcohol dehydrogenation with Mn(III)-porphyrin complex Mn7.
Scheme 15: N-Methylation of nitroarenes with methanol using catalyst Mn3.
Scheme 16: Mechanism of manganese-catalyzed methylation of nitroarenes using Mn3 as the catalyst.
Scheme 17: Bidentate manganese complex Mn8 applied for the N-alkylation of primary anilines with alcohols. aOn...
Scheme 18: N-Alkylation of amines with alcohols in the presence of manganese salts and triphenylphosphine as t...
Scheme 19: N-Alkylation of diazo compounds with alcohols using catalyst Mn9.
Scheme 20: Proposed mechanism for the amination of alcohols with diazo compounds catalyzed by catalyst Mn9.
Scheme 21: Mn1 complex-catalyzed synthesis of polyethyleneimine from ethylene glycol and ethylenediamine.
Scheme 22: Bis-triazolylidene-manganese complex Mn10 for the N-alkylation of amines with alcohols.
Figure 2: Manganese complexes applied for C-alkylation reactions of ketones with alcohols.
Scheme 23: General scheme for the C–C bond formation with alcohols and ketones.
Scheme 24: Mn1 complex-catalyzed α-alkylation of ketones with primary alcohols.
Scheme 25: Mechanism for the Mn1-catalyzed alkylation of ketones with alcohols.
Scheme 26: Phosphine-free in situ-generated manganese catalyst for the α-alkylation of ketones with primary al...
Scheme 27: Plausible mechanism for the Mn-catalyzed α-alkylation of ketones with alcohols.
Scheme 28: α-Alkylation of esters, ketones, and amides using alcohols catalyzed by Mn11.
Scheme 29: Mono- and dialkylation of methylene ketones with primary alcohols using the Mn(acac)2/1,10-phenanth...
Scheme 30: Methylation of ketones with methanol and deuterated methanol.
Scheme 31: Methylation of ketones and esters with methanol. a50 mol % of t-BuOK were used, bCD3OD was used ins...
Scheme 32: Alkylation of ketones and secondary alcohols with primary alcohols using Mn4.
Scheme 33: Bidentate manganese-NHC complex Mn6 applied for the synthesis of alkylated ketones using alcohols.
Scheme 34: Mn1-catalyzed synthesis of substituted cycloalkanes by coupling diols and secondary alcohols or ket...
Scheme 35: Proposed mechanism for the synthesis of cycloalkanes via BH method.
Scheme 36: Synthesis of various cycloalkanes from methyl ketones and diols catalyze by Mn13. aReaction time wa...
Scheme 37: N,N-Amine–manganese complex (Mn13)-catalyzed alkylation of ketones with alcohols.
Scheme 38: Naphthyridine‑N‑oxide manganese complex Mn14 applied for the alkylation of ketones with alcohols. a...
Scheme 39: Proposed mechanism of the naphthyridine‑N‑oxide manganese complex (Mn14)-catalyzed alkylation of ke...
Scheme 40: α-Methylation of ketones and indoles with methanol using Mn15.
Scheme 41: α-Alkylation of ketones with primary alcohols using Mn16. aNMR yield.
Figure 3: Manganese complexes used for coupling of secondary and primary alcohols.
Scheme 42: Alkylation of secondary alcohols with primary alcohols catalyzed by phosphine-free catalyst Mn17. a...
Scheme 43: PNN-Manganese complex Mn18 for the alkylation of secondary alcohols with primary alcohols.
Scheme 44: Mechanism for the Mn-pincer catalyzed C-alkylation of secondary alcohols with primary alcohols.
Scheme 45: Upgrading of ethanol with methanol for isobutanol production.
Scheme 46: Mn-Pincer catalyst Mn19 applied for the β-methylation of alcohols with methanol. a2.0 mol % of Mn19...
Scheme 47: Functionalized ketones from primary and secondary alcohols catalyzed by Mn20. aMn20 (5 mol %), NaOH...
Scheme 48: Synthesis of γ-disubstituted alcohols and β-disubstituted ketones through Mn9-catalyzed coupling of...
Scheme 49: Proposed mechanism for the Mn9-catalyzed synthesis of γ-disubstituted alcohols and β-disubstituted ...
Scheme 50: Dehydrogenative coupling of ethylene glycol and primary alcohols catalyzed by Mn4.
Scheme 51: Mn18-cataylzed C-alkylation of unactivated esters and amides with alcohols.
Scheme 52: Alkylation of amides and esters using Mn21.
Scheme 53: α-Alkylation of nitriles with primary alcohols using in situ-generated manganese catalyst.
Scheme 54: Proposed mechanism for the α-alkylation of nitriles with primary alcohols.
Scheme 55: Mn9-catalyzed α-alkylation of nitriles with primary alcohols. a1,4-Dioxane was used as solvent, 24 ...
Figure 4: Manganese complexes used for alkylation of heterocyclic compounds.
Scheme 56: Aminomethylation of aromatic compounds with secondary amines and methanol catalyzed by Mn22.
Scheme 57: Regioselective alkylation of indolines with alcohols catalyzed by Mn9. aMn9 (4 mol %), 48 h.
Scheme 58: Proposed mechanism for the C- and N-alkylation of indolines with alcohols.
Scheme 59: C-Alkylation of methyl N-heteroarenes with primary alcohols catalyzed by Mn1. aTime was 60 h.
Scheme 60: C-Alkylation of oxindoles with secondary alcohols.
Scheme 61: Plausible mechanism for the Mn23-catalyzed C-alkylation of oxindoles with secondary alcohols.
Scheme 62: Synthesis of C-3-alkylated products by coupling alcohols with indoles and aminoalcohols.
Scheme 63: C3-Alkylation of indoles using Mn1.
Scheme 64: C-Methylation of indoles with Mn15 and methanol.
Scheme 65: α-Alkylation of 2-oxindoles with primary and secondary alcohols catalyzed by Mn25. aReaction carrie...
Scheme 66: Dehydrogenative alkylation of indolines with Mn1. aMn1 (5.0 mol %) was used.
Scheme 67: Synthesis of bis(indolyl)methane derivatives from indoles and alcohols catalyzed by Mn26. aMn26 (5....
Scheme 68: One-pot synthesis of pyrimidines via BH.
Scheme 69: Synthesis of pyrroles from alcohols and aminoalcohols using Mn4.
Scheme 70: Synthesis of pyrroles via multicomponent reaction catalyzed by Mn12.
Scheme 71: Friedländer quinoline synthesis using an in situ-generated phosphine-free manganese catalyst.
Scheme 72: Quinoline synthesis using bis-N-heterocyclic carbene-manganese catalyst Mn6.
Scheme 73: Quinoline synthesis using manganese(III)-porphyrin catalyst Mn7.
Scheme 74: Manganese-catalyzed tetrahydroquinoline synthesis via borrowing BH.
Scheme 75: Proposed mechanism for the manganese-catalyzed tetrahydroquinoline synthesis.
Scheme 76: Synthesis of C3-alkylated indoles using Mn24.
Scheme 77: Synthesis of C-3-alkylated indoles using Mn1.
Scheme 78: C–C Bond formation by coupling of alcohols and ylides.
Scheme 79: C-Alkylation of fluorene with alcohols catalyzed by Mn24.
Scheme 80: Proposed mechanism for the C-alkylation of fluorene with alcohols catalyzed by Mn24.
Scheme 81: α-Alkylation of sulfones using Mn-PNN catalyst Mn28.
Chiral phosphoric acid-catalyzed transfer hydrogenation of 3,3-difluoro-3H-indoles
- Yumei Wang,
- Guangzhu Wang,
- Yanping Zhu and
- Kaiwu Dong
Beilstein J. Org. Chem. 2024, 20, 205–211, doi:10.3762/bjoc.20.20
- synthesis of optically active difluoro-substituted indoline derivatives starting from the corresponding 3H-indoles by chiral phosphoric acid-catalyzed transfer hydrogenation was developed. Using Hantzsch ester as the hydrogen source under mild reaction conditions, the target products can be obtained with
- isostere of polar functional groups [5][6]. Chiral indoline is an important member of the class of nitrogen-containing heterocyclic compounds that often exhibits various pharmaceutical activities and exists in many natural products [7][8]. The enantioselective synthesis of chiral indolines has received
- and practicability of this approach, a 2 mmol scale experiment of the asymmetric transfer hydrogenation of 1a was carried out (Scheme 3). Under the standard reaction conditions, 0.5 gram (98% yield) of chiral difluorinated indoline 2a was obtained with 95% ee. Based on previous studies [31], a
Graphical Abstract
Figure 1: Structures of bioactive fluorinated indole derivatives.
Scheme 1: Synthesis of chiral indolines via asymmetric reduction.
Scheme 2: Substrate scope of 3,3-difluoro-3H-indoles.
Scheme 3: Experiment at 2 mmol scale.
Figure 2: Proposed mechanism for the transfer hydrogenation reaction.
Construction of diazepine-containing spiroindolines via annulation reaction of α-halogenated N-acylhydrazones and isatin-derived MBH carbonates
- Xing Liu,
- Wenjing Shi,
- Jing Sun and
- Chao-Guo Yan
Beilstein J. Org. Chem. 2023, 19, 1923–1932, doi:10.3762/bjoc.19.143
- . Additionally, the similar reaction with α-halogenated N-tosylhydrazones also afforded N-tosyl-substituted spiro[indoline-3,5'-[1,2]diazepine] in satisfactory yields. This protocol provides a convenient approach for the assembly of diverse highly functionalized spiro[indoline-3,5'-[1,2]diazepines] and also
- efficient synthesis of spiro[azepine-4,3'-indoline] derivatives via the [4 + 3] cycloaddition reaction of bromo-substituted isatin-derived MBH adducts and N-(o-chloromethyl)arylamides. In this efficient protocol, the reactive allylic phosphonium ylides and aza-o-quinone methides were generated in situ and
- satisfactory yields and with good diastereoselectivity (reaction 3, Scheme 1) [57]. Very recently, we found that the base-catalyzed [4 + 3] cycloaddition reaction of isatin-derived MBH carbonates with various α,β-unsaturated N-arylaldimines affords spiro[indoline-3,5'-pyrrolo[3,4-b]azepine] derivatives
Graphical Abstract
Scheme 1: Representative [4 + 3] cycloaddition reactions of MBH carbonates derived from isatins.
Scheme 2: Synthesis of spiro[indoline-3,5'-[1,2]diazepines] 3a–m. Conditions: α-halogenated acylhydrazone (0....
Scheme 3: Synthesis of spiro[indoline-3,5'-[1,2]diazepines] 5a–g. Conditions: α-halogenated acylhydrazone (0....
Scheme 4: Synthesis of dihydrospiro[indoline-3,5'-[1,2]diazepines] 7a–n. Conditions: α-halogenated N-tosylhyd...
Figure 1: Single crystal structure of the spiro compound 7a.
Scheme 5: Proposed reaction mechanism.
Scheme 6: Gram-scale synthesis of compound 7c.
N-Boc-α-diazo glutarimide as efficient reagent for assembling N-heterocycle-glutarimide diads via Rh(II)-catalyzed N–H insertion reaction
- Grigory Kantin,
- Pavel Golubev,
- Alexander Sapegin,
- Alexander Bunev and
- Dmitry Dar’in
Beilstein J. Org. Chem. 2023, 19, 1841–1848, doi:10.3762/bjoc.19.136
- pyrazole derivatives (including indazole), benzimidazole, 1,2,3-triazole, indole, carbazole, indoline, quinazoline, and isoquinoline. Nevertheless, many heterocyclic motifs still remain beyond the attention of researchers. For example, glutarimides that incorporate tetrazole and 1,2,4-triazole substituents
Graphical Abstract
Figure 1: Glutarimide-based immunomodulatory drugs (IMiDs) and CRBN ligands.
Scheme 1: Main literature approaches towards α-hetaryl glutarimides 1 (routes A and B) and new “diazo” method...
Scheme 2: Preparation of diazo reagent 5.
Scheme 3: Scope of NH insertion reaction of N-Boc-α-diazo glutarimide and various N-heterocycles. aIsolated y...
Figure 2: Examples of α-carbonyl NH-heterocycles for which N–H insertion products could not be obtained.
Scheme 4: Examples of N-deprotection of α-modified glutarimides 1.
Scheme 5: Preparation of NH2-containing derivative 10 via reduction of 6n.
Decarboxylative 1,3-dipolar cycloaddition of amino acids for the synthesis of heterocyclic compounds
- Xiaofeng Zhang,
- Xiaoming Ma and
- Wei Zhang
Beilstein J. Org. Chem. 2023, 19, 1677–1693, doi:10.3762/bjoc.19.123
- olefinic oxindoles to replace maleimides, the reactions gave spiro[indoline-tetrahydropyrrolothiazole] products 30 in 55–70% with greater than 4:1 dr [76]. The reaction mechanism suggests that the reaction of cysteine with arylaldehydes gives N,S-acetals 27 which convert to AMYs 28 after decarboxlyation
Graphical Abstract
Figure 1: Classification of AMYs.
Scheme 1: Aminoester- and amino acid-based AMYs for single and double [3+2] cycloadditions.
Scheme 2: Formation of semi-stabilized AMYs B1 from pyrrolidines.
Scheme 3: Cyclic amine-based AMYs A3 and B1 for [3 + 2] cycloadditions.
Scheme 4: Proposed double cycloaddition reactions involving semi-stabilized AMYs.
Scheme 5: [3 + 2] Cycloaddition for the synthesis of trifluoromethylated pyrrolidines 9.
Figure 2: Biologically interesting pyrrolizidines.
Scheme 6: Double cycloadditions with glycine for the synthesis of products 10 (dr > 9:1).
Scheme 7: Double cycloadditions with α-substituted amino acids leading to products 11 (≈8.5:1 dr).
Scheme 8: Stereochemistry for the formation of products 10 or 11.
Scheme 9: One-pot and stepwise double cycloadditions. Conditions: i) MeCN (0.02 M), 90 °C, 6 h; ii) then AcOH...
Figure 3: Biologically interesting spirooxindole-pyrrolizidines.
Scheme 10: Double cycloadditions for the synthesis of bis[spirooxindole-pyrrolizidine]s.
Scheme 11: Mechanism for the diastereoselective synthesis of bis[spirooxindole-pyrrolizidine]s.
Scheme 12: Stepwise synthesis of triazolobenzodiazepine 21a.
Scheme 13: One-pot synthesis of triazolobenzodiazepines.
Figure 4: Bioactive triazolobenzodiazepine derivatives.
Scheme 14: One-pot synthesis of tetrahydropyrroloquinazolines.
Scheme 15: One-pot synthesis of tetrahydropyrrolobenzodiazepines.
Figure 5: Bioactive pyrroloquinazolines and pyrrolobenzodiazepines.
Scheme 16: Stepwise synthesis of pyrrolo[2,1-a]isoquinolines.
Figure 6: Bioactive pyrrolo[2,1-a]isoquinolines and hexahydropyrrolo[2,1-a]isoquinolines.
Figure 7: Bioactive tetrahydropyrrolothiazoles.
Scheme 17: Pseudo-four-component reaction for the synthesis of tetrahydropyrrolothiazoles 29 and 30 (>4:1 dr).
Scheme 18: One-pot two-step synthesis of spirooxindole-pyrrolothiazoles 31 (>4:1 dr).
Selective construction of dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] via three-component reaction
- Ziying Xiao,
- Fengshun Xu,
- Jing Sun and
- Chao-Guo Yan
Beilstein J. Org. Chem. 2023, 19, 1234–1242, doi:10.3762/bjoc.19.91
- dispiro[indoline-3,2'-quinoline-3',3''-indoline] derivatives in good yields and with high diastereoselectivity. On the other hand, a similar reaction of the dimedone adducts of 3-phenacylideneoxindoles afforded unique dispiro[indoline-3,2'-pyrrole-3',3''-indoline] derivatives with a cyclohexanedione
- ][59][60][61][62], we investigated the base-promoted annulation reaction of dimedone adducts of 3-methyleneoxindoles, with isatin and ammonium acetate. It was unexpectedly found that novel dispiro[indoline-3,2'-quinoline-3',3''-indoline] and dispiro[indoline-3,2'-pyrrole-3',3''-indoline] were
- the three-component reaction. To our surprise, instead of the above mentioned dispiro[indoline-3,2'-quinoline-3',3''-indolines] 3a–m, the novel dispiro[indoline-3,2'-pyrrole-3',3''-indoline] derivatives 4a–i were obtained in high yields. The results are summarized in Table 3. The structural analysis
Graphical Abstract
Scheme 1: Representative cascade reactions of Michael adducts of 3-methyleneoxindoles.
Figure 1: Crystal structure of dispiro compound 3a.
Figure 2: Crystal structure of compound 4a.
Scheme 2: Proposed reaction mechanism.
Exploring the role of halogen bonding in iodonium ylides: insights into unexpected reactivity and reaction control
- Carlee A. Montgomery and
- Graham K. Murphy
Beilstein J. Org. Chem. 2023, 19, 1171–1190, doi:10.3762/bjoc.19.86
- ]. They disclosed a reaction between acyclic iodonium ylides (e.g., 31/ I-10) and tertiary amines 32, which produced indoline rings 33 by forging two new C–C bonds between the ylidic carbon and unactivated positions on the amine (Scheme 5). In 2020, they disclosed a more complex variant of this reaction
- an example of β-dicarbonyl functionalization. Metal-free cyclopropanations of iodonium ylides, either as intermolecular (a) or intramolecular processes (b, c). Metal-free intramolecular cyclopropanation of iodonium ylides. Reaction of ylide 6 with diphenylketene to form lactone 24 and 25. Indoline
- synthesis from acyclic iodonium ylide 31 and tertiary amines. N-Heterocycle synthesis from acyclic iodonium ylide 31 and secondary amines. Indoline synthesis from acyclic iodonium ylides 39 and tertiary
Graphical Abstract
Figure 1: Generic representation of halogen bonding.
Figure 2: Quantitative evaluation of σ-holes in monovalent iodine-containing compounds; and, qualitative mole...
Figure 3: Quantitative evaluation of σ-holes in hypervalent iodine-containing molecules; and, qualitative MEP...
Figure 4: Quantitative evaluation of σ-holes in iodonium ylides; and, qualitative MEP map of I-12 from −0.083...
Scheme 1: Outline of possible reaction pathways between iodonium ylides and Lewis basic nucleophiles (top); a...
Scheme 2: Metal-free cyclopropanations of iodonium ylides, either as intermolecular (a) or intramolecular pro...
Figure 5: Zwitterionic mechanism for intramolecular cyclopropanation of iodonium ylides (left); and, stepwise...
Scheme 3: Metal-free intramolecular cyclopropanation of iodonium ylides.
Figure 6: Concerted cycloaddition pathway for the metal-free, intramolecular cyclopropanation of iodonium yli...
Scheme 4: Reaction of ylide 6 with diphenylketene to form lactone 24 and 25.
Figure 7: Nucleophilic (top) and electrophilic (bottom) addition pathways proposed by Koser and Hadjiarapoglo...
Scheme 5: Indoline synthesis from acyclic iodonium ylide 31 and tertiary amines.
Scheme 6: N-Heterocycle synthesis from acyclic iodonium ylide 31 and secondary amines.
Figure 8: Proposed mechanism for the formation of 33a from iodonium ylides and amines, involving an initial h...
Scheme 7: Indoline synthesis from acyclic iodonium ylides 39 and tertiary amines under blue light photocataly...
Scheme 8: Metal-free cycloproponation of iodonium ylides under blue LED irradiation. aUsing trans-β-methylsty...
Figure 9: Proposed mechanism of the cyclopropanation between iodonium ylides and alkenes under blue LED irrad...
Scheme 9: Formal C–H alkylation of iodonium ylides by nucleophilic heterocycles under blue LED irradiation.
Figure 10: Proposed mechanism of the formal C–H insertion of pyrrole under blue LED irradiation.
Scheme 10: X–H insertions between iodonium ylides and carboxylic acids, phenols and thiophenols.
Figure 11: Mechanistic proposal for the X–H insertion reactions of iodonium ylides.
Scheme 11: Radiofluorination of biphenyl using iodonium ylides 54a–e derived from various β-dicarbonyl auxilia...
Scheme 12: Radiofluorination of arenes using spirocycle-derived iodonium ylides 56.
Scheme 13: Radiofluorination of arenes using SPIAd-derived iodonium ylides 58.
Figure 12: Calculated reaction coordinate for the radiofluorination of iodonium ylide 60.
Scheme 14: Radiofluorination of iodonium ylides possessing various ortho- and para-substituents on the iodoare...
Figure 13: Difference in Gibbs activation energy for ortho- or para-anisyl derived iodonium ylides 63a and 63b....
Figure 14: Proposed equilibration of intermediates to transit between 64a (the initial adduct formed between 6...
Scheme 15: Comparison of 31 and ortho-methoxy iodonium ylide 39 in rhodium-catalyzed cyclopropanation and cycl...
Figure 15: X-ray crystal structure of dimeric 39 [6], (CCDC# 893474) [143,144].
Scheme 16: Enaminone synthesis using diazonium and iodonium ylides.
Figure 16: Transition state calculations for enaminone synthesis from iodonium ylides and thioamides.
Scheme 17: The reaction between ylides 73a–f and N-methylpyrrole under 365 nm UV irradiation.
Figure 17: Crystal structures of 76c (top) and 76e (bottom) [101], (CCDC# 2104180 & 2104181) [143,144].
Photoredox catalysis harvesting multiple photon or electrochemical energies
- Mattia Lepori,
- Simon Schmid and
- Joshua P. Barham
Beilstein J. Org. Chem. 2023, 19, 1055–1145, doi:10.3762/bjoc.19.81
- indoline scaffolds (22a,b) via a radical-polar crossover mechanism (Figure 12C) [65], showcasing the power of conPET in dearomatization reactions. Finally, the synthesis of tetraphenylphosphonium chloride (20a) could be scaled up efficiently in an operationally very simple continuous-flow setup with only
Graphical Abstract
Figure 1: Oxidative and reductive activations of organic compounds harvesting photoredox catalysis.
Figure 2: General catalytic cycles of radical ion conPET (left) and radical ion e-PRC (right).
Figure 3: “Beginner’s guide”: comparison between advantages, capacities, and prospectives of conPET and PEC.
Figure 4: A) conPET reductive dehalogenation of aryl halides with PDI. B) Reductive C–H arylation with pyrrol...
Figure 5: A) Chromoselective mono- and disubstitution or polybrominated pyrimidines with pyrroles. B) Sequent...
Figure 6: A) Synthesis of pyrrolo[1,2-a]quinolines. B) Synthesis of ullazines.
Figure 7: A) Reductive phosphorylation of aryl halides via conPET. B) Selected examples from the substrate sc...
Figure 8: A) Reductive dehalogenation of aryl halides via conPET and selected examples from the substrate sco...
Figure 9: A) Reductive C–H arylation of aryl halides via conPET (top) and selected examples from the substrat...
Figure 10: A) Reductive hydrodehalogenation of aryl halides with Mes-Acr-BF4. B) Selected examples from the su...
Figure 11: A) Reductive hydrodechlorination of aryl chlorides with 4-DPAIPN. B) Proposed formation of CO2•−. C...
Figure 12: A) Reductive conPET borylation with 3CzEPAIPN (top) and selected examples from the substrate scope ...
Figure 13: Scale-up of conPET phosphorylation with 3CzEPAIPN.
Figure 14: A) Borylation of 1d. B) Characteristics and structure of PC1 with green and red parts showing the l...
Figure 15: A) Reductive C–H arylation scope with polysulfide conPET (top) and selected examples from the subst...
Figure 16: Scale-up of A) C–H arylation and B) dehaloborylation with polysulfide photocatalysis in continuous-...
Figure 17: A) Formation of [Ir1]0 and [Ir2]0 upon PET between [Ir1]+ and Et3N. B) Mechanism of multi-photon ta...
Figure 18: A) Reductive hydrodehalogenation of aryl halides via multi-photon tandem photocatalysis. B) Selecte...
Figure 19: A) Carbonylative amidation of aryl halides in continuous flow. B) Selected examples from the substr...
Figure 20: A) General scheme for reductive (RQ) and oxidative quenching (OQ) protocols using [FeIII(btz)3](PF6)...
Figure 21: A) Carbonylative amidation of alkyl iodides with [IrIII(ppy)2(dtbbpy)]PF6. B) Selected examples fro...
Figure 22: A) Carboxylative C–N bond cleavage in cyclic amines. B) Selected examples from the substrate scope....
Figure 23: A) Formal reduction of alkenes to alkanes via transfer hydrogenation. B) Selected examples from the...
Figure 24: A) Birch-type reduction of benzenes with PMP-BPI. B) Selected examples from the substrate scope (sc...
Figure 25: Proposed mechanism of the OH− mediated conPET Birch-type reduction of benzene via generation of sol...
Figure 26: Reductive detosylation of N-tosylated amides with Mes-Acr-BF4. B) Selected examples from the substr...
Figure 27: A) Reductive detosylation of N-tosyl amides by dual PRC. B) Selected examples from the substrate sc...
Figure 28: A) Mechanism of the dual PRC based on PET between [Cu(dap)2]+ and DCA. B) Mechanism of the dual PRC...
Figure 29: A) N–O bond cleavage in Weinreb amides with anthracene. B) N–O bond cleavage in Weinreb amides rely...
Figure 30: A) Pentafluorosulfanylation and fluoride elimination. B) Mechanism of the pentafluorosulfanylation ...
Figure 31: A) α-Alkoxypentafluorosulfanylation (top) and selected examples from the substrate scope (bottom). ...
Figure 32: A) Oxidative amination of arenes with azoles catalyzed by N-Ph PTZ. B) Selected examples from the s...
Figure 33: A) C(sp3)–H bond activation by HAT via chloride oxidation by *N-Ph PTZ•+. B) Proposed mechanism for...
Figure 34: A) Recycling e-PRC C–H azolation of electron-rich arenes with pyrazoles using Mes-Acr+ as a photoca...
Figure 35: A) Radical ion e-PRC direct oxidation of unactivated arenes using TAC+ as an electro-activated phot...
Figure 36: A) Radical ion e-PRC direct oxidation of unactivated arenes using TPA as an electro-activated photo...
Figure 37: Proposed mechanism (top) and mode of preassembly (bottom).
Figure 38: A) Possible preassemblies of reactive (left) vs unreactive (right) arenes. B) Calculated spin densi...
Figure 39: A) Recycling e-PRC C(sp2 )–H acetoxylation of arenes using DDQ as a photocatalyst. B) Proposed cata...
Figure 40: Gram scale hydroxylation of benzene in a recirculated flow setup.
Figure 41: A) Radical ion e-PRC vicinal diamination of alkylarenes using TAC+ as an electro-activated photocat...
Figure 42: A) Sequential oxygenation of multiple adjacent C–H bonds under radical ion e-PRC using TAC+ as an e...
Figure 43: A) Enantioselective recycling e-PRC cyanation of benzylic C–H bonds using ADQS as photocatalyst. B)...
Figure 44: Proposed tandem mechanism by Xu and co-workers.
Figure 45: A) Enantioselective recycling e-PRC decarboxylative cyanation using Cu(acac)2, Ce(OTf)3 and a box l...
Figure 46: A) Enantioselective recycling e-PRC benzylic cyanation using Cu(MeCN)4BF4, box ligand and anthraqui...
Figure 47: A) Radical ion e-PRC acetoxyhydroxylation of aryl olefins using TAC+ as an electro-activated photoc...
Figure 48: Selected examples from the substrate scope.
Figure 49: Photoelectrochemical acetoxyhydroxylation in a recirculated flow setup.
Figure 50: A) Radical ion e-PRC aminooxygenation of aryl olefins using TAC+ as an electro-activated photocatal...
Figure 51: A) Recycling e-PRC C–H alkylation of heteroarenes with organic trifluoroborates using Mes-Acr+ as p...
Figure 52: A) Recycling e-PRC decarboxylative C–H alkylation of heteroarenes using CeCl3·7H2O as catalyst. B) ...
Figure 53: A) Recycling e-PRC decarboxylative C–H alkylation of heteroarenes using Fe(NH4)2(SO4)2·6H2O as cata...
Figure 54: A) Recycling e-PRC C–H alkylation of heteroarenes with alkyl oxalates and 4CzIPN as photocatalyst. ...
Figure 55: A) Recycling e-PRC decarboxylative C–H carbamoylation of heteroarenes using 4CzIPN as photocatalyst...
Figure 56: A) Photoelectrochemical HAT-mediated hydrocarbon activation via the chlorine radical. B) Proposed m...
Figure 57: A) Selected examples from the substrate scope. B) Gram and decagram scale semi-continuous flow PEC ...
Figure 58: A) Photoelectrochemical HAT-mediated dehydrogenative coupling of benzothiazoles with aliphatic C–H ...
Figure 59: A) Photoelectrochemical HAT activation of ethers using electro-activated TAC+ as photocatalyst. B) ...
Figure 60: Selected examples from the substrate scope.
Figure 61: A) Photoelectrochemical HAT-mediated synthesis of alkylated benzimidazo-fused isoquinolinones using...
Figure 62: A) Decoupled photoelectrochemical cerium-catalyzed oxydichlorination of alkynes using CeCl3 as cata...
Figure 63: Proposed decoupled photoelectrochemical mechanism.
Figure 64: A) Decoupled photoelectrochemical ring-opening bromination of tertiary cycloalkanols using MgBr2 as...
Figure 65: A) Recycling e-PRC ring-opening functionalization of cycloalkanols using CeCl3 as catalyst. B) Prop...
Figure 66: Selected examples from the substrate scope of the PEC ring-opening functionalization.
Figure 67: A) Radical ion e-PRC reduction of chloro- and bromoarenes using DCA as catalyst and various accepto...
Figure 68: A) Screening of different phthalimide derivatives as catalyst for the e-PRC reduction of aryl halid...
Figure 69: Screening of different organic catalysts for the e-PRC reduction of trialkylanilium salts.
Figure 70: A) e-PRC reduction of phosphonated phenols and anilinium salts. B) Selected examples from the subst...
Figure 71: A) ConPET and e-PRC reduction of 4-bromobenzonitrile using a naphthalene diimide (NDI) precatalyst ...
Figure 72: A) Radical ion e-PRC reduction of phosphinated aliphatic alcohols with n-BuO-NpMI as catalyst. B) C...
Figure 73: Selected examples from the substrate scope.
Figure 74: A) Recycling e-PRC reductive dimerization of benzylic chlorides using a [Cu2] catalyst. B) Proposed...
Figure 75: A) Decoupled photoelectrochemical C–H alkylation of heteroarenes through deamination of Katritzky s...
Figure 76: Proposed mechanism by Chen and co-workers.
Copper-catalyzed N-arylation of amines with aryliodonium ylides in water
- Kasturi U. Nabar,
- Bhalchandra M. Bhanage and
- Sudam G. Dawande
Beilstein J. Org. Chem. 2023, 19, 1008–1014, doi:10.3762/bjoc.19.76
- ) as a product with 59% yield. Similarly, the reaction of cyclic secondary amines also resulted in arylation under the optimal reaction conditions to give products 3s–v with 42–48% yields. The treatment of indoline with iodonium ylide 2b in the presence of 10 mol % of CuSO4·5H2O affords product 3w in
Graphical Abstract
Figure 1: Representative examples of N-arylamines.
Scheme 1: N-Arylation of amines with hypervalent iodine reagents.
Scheme 2: N-Arylation of primary amines with iodonium ylide. Reaction conditions: 0.2 mmol aniline 1, 0.24 mm...
Scheme 3: N-Arylation of secondary amines with iodonium ylide.
Group 13 exchange and transborylation in catalysis
- Dominic R. Willcox and
- Stephen P. Thomas
Beilstein J. Org. Chem. 2023, 19, 325–348, doi:10.3762/bjoc.19.28
- reduction with Me2S·BH3 was investigated by Fontaine, and applied to a catalytic variant using HBpin as the turnover reagent (Scheme 7) [70]. Computational analysis showed two plausible, cooperative catalytic cycles: 1) hydroboration of indole 25 with BH3 to give a H2B-N-indoline 26, which then underwent B
- ‒N/B‒H transborylation with HBpin to regenerate BH3 and give the N-Bpin-indoline product 27; 2) two molecules of H2B-N-indoline underwent rearrangement to regenerate BH3 and gave a bisindolinylborane 28. The bis-N-indolinylborane then underwent B‒N/B‒H transborylation with HBpin to regenerate H2B-N
- -indoline and gave the Bpin-N-indoline product 27; this was suggested as the major pathway (Scheme 7). Thomas et al. reported the H-B-9-BBN-catalysed reductive cyanation of enones with HBpin and N-cyano-N-phenyl-p-toluenesulfonamide (NCTS) (Scheme 8) [71]. The reaction was proposed to proceed by 1,4
Graphical Abstract
Scheme 1: Group 13 exchange.
Scheme 2: Borane-catalysed hydroboration of alkynes and the proposed mechanism.
Scheme 3: a) Borane-catalysed hydroboration of alkenes and the proposed mechanism. b) H-B-9-BBN-catalysed dou...
Scheme 4: a) Amine-borane-catalysed C‒H borylation of heterocycles and the proposed mechanism. b) Benzoic aci...
Scheme 5: Bis(pentafluorophenyl)borane-catalysed dimerisation of allenes and the proposed mechanism.
Scheme 6: Alkoxide-promoted hydroboration of heterocycles and the proposed mechanism.
Scheme 7: Borane-catalysed reduction of indoles and the proposed mechanism.
Scheme 8: H-B-9-BBN-catalysed hydrocyanation of enones and the proposed mechanism.
Scheme 9: Borane-catalysed hydroboration of nitriles and the proposed mechanism.
Scheme 10: Myrtanylborane-catalysed asymmetric reduction of propargylic ketones and the proposed mechanism.
Scheme 11: H-B-9-BBN-catalysed C–F esterification of alkyl fluorides and the proposed mechanism.
Scheme 12: H-B-9-BBN-catalysed 1,4-hydroboration of enones and the proposed mechanism.
Scheme 13: Boric acid-promoted reduction of esters, lactones, and carbonates and the proposed mechanism.
Scheme 14: H-B-9-BBN-catalysed reductive aldol-type reaction and the proposed mechanism.
Scheme 15: H-B-9-BBN-catalysed diastereoselective allylation of ketones and the Ph-BBD-catalysed enantioselect...
Scheme 16: H-B-9-BBN-catalysed C–F arylation of benzyl fluorides and the proposed mechanism.
Scheme 17: Borane-catalysed S‒H borylation of thiols and the proposed mechanism.
Scheme 18: Borane-catalysed hydroalumination of alkenes and allenes.
Scheme 19: a) Aluminium-catalysed hydroboration of alkynes and example catalysts. b) Deprotonation mechanistic...
Scheme 20: Aluminium-catalysed hydroboration of alkenes and the proposed mechanism.
Scheme 21: Aluminium-catalysed C–H borylation of terminal alkynes and the proposed mechanism.
Scheme 22: Aluminium-catalysed dehydrocoupling of amines, alcohols, and thiols with H-B-9-BBN or HBpin and the...
Scheme 23: Aluminium-catalysed hydroboration of unsaturated compounds and the general reaction mechanism.
Scheme 24: a) Gallium-catalysed asymmetric hydroboration of ketones and the proposed mechanism. b) Gallium-cat...
Scheme 25: Gallium(I)-catalysed allylation/propargylation of acetals and aminals and the proposed mechanism.
Scheme 26: Indium(I)-catalysed allylation/propargylation of acetals, aminals, and alkyl ethers.
Scheme 27: Iron–indium cocatalysed double hydroboration of nitriles and the proposed mechanism.
Figure 1: a) The number of reports for a given group 13 exchange in catalysis. b) Average free energy barrier...
1,4-Dithianes: attractive C2-building blocks for the synthesis of complex molecular architectures
- Bram Ryckaert,
- Ellen Demeyere,
- Frederick Degroote,
- Hilde Janssens and
- Johan M. Winne
Beilstein J. Org. Chem. 2023, 19, 115–132, doi:10.3762/bjoc.19.12
- ). The use of the much stronger triflic acid actually paradoxically protects the rather sensitive indoline cycloaddition products such as the dearomatized product 100, derived from skatole (99), by keeping the adduct and all intermediates in their protonated form throughout the progress of the reaction
Graphical Abstract
Scheme 1: 1,3-Dithianes as useful synthetic building blocks: a) general synthetic utility (in Corey–Seebach-t...
Scheme 2: Metalation of other saturated heterocycles is often problematic due to β-elimination [16,17].
Scheme 3: Thianes as synthetic building blocks in the construction of complex molecules [18].
Figure 1: a) 1,4-Dithiane-type building blocks that can serve as C2-synthons and b) examples of complex targe...
Scheme 4: Synthetic availability of 1,4-dithiane-type building blocks.
Scheme 5: Dithiins and dihydrodithiins as pseudoaryl groups [36-39].
Scheme 6: Metalation of other saturated heterocycles is often problematic due to β-elimination [40-42].
Figure 2: Reactive conformations leading to β-fragmentation for lithiated 1,4-dithianes and 1,4-dithiin.
Scheme 7: Mild metalation of 1,4-dithiins affords stable heteroaryl-magnesium and heteroaryl-zinc-like reagen...
Scheme 8: Dithiin-based dienophiles and their use in synthesis [33,49-54].
Scheme 9: Dithiin-based dienes and their use in synthesis [55-57].
Scheme 10: Stereoselective 5,6-dihydro-1,4-dithiin-based synthesis of cis-olefins [42,58].
Scheme 11: Addition to aldehydes and applications in stereoselective synthesis.
Figure 3: Applications in the total synthesis of complex target products with original attachment place of 1,...
Scheme 12: Direct C–H functionalization methods for 1,4-dithianes [82,83].
Scheme 13: Known cycloaddition reactivity modes of allyl cations [84-100].
Scheme 14: Cycloadditions of 1,4-dithiane-fused allyl cations derived from dihydrodithiin-methanol 90 [101-107].
Scheme 15: Dearomative [3 + 2] cycloadditions of unprotected indoles with 1,4-dithiane-fused allyl alcohol 90 [30]....
Scheme 16: Comparison of reactivity of dithiin-fused allyl alcohols and similar non-cyclic sulfur-substituted ...
Scheme 17: Applications of dihydrodithiins in the rapid assembly of polycyclic terpenoid scaffolds [108,109].
Scheme 18: Dihydrodithiin-mediated allyl cation and vinyl carbene cycloadditions via a gold(I)-catalyzed 1,2-s...
Scheme 19: Activation mode of ethynyldithiolanes towards gold-coordinated 1,4-dithiane-fused allyl cation and ...
Scheme 20: Desulfurization problems.
Scheme 21: oxidative decoration strategies for 1,4-dithiane scaffolds.
