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Search for "bromine" in Full Text gives 344 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of ether lipids: natural compounds and analogues
- Marco Antônio G. B. Gomes,
- Alicia Bauduin,
- Chloé Le Roux,
- Romain Fouinneteau,
- Wilfried Berthe,
- Mathieu Berchel,
- Hélène Couthon and
- Paul-Alain Jaffrès
Beilstein J. Org. Chem. 2023, 19, 1299–1369, doi:10.3762/bjoc.19.96
- mesylated to 29.2. Then, a bromine atom was introduced via a nucleophilic substitution with LiBr in acetone to form 29.3. Finally, the primary bromide was used to introduce different ammonium salts as illustrated with compound 29.4. A variation of this sequence consisted in placing an ether function in
Graphical Abstract
Figure 1: Chemical structure of some natural ether lipids (ELs).
Figure 2: Synthesis of lyso-PAF and PAF from 1-O-alkylglycerol [64].
Figure 3: Synthesis of lyso-PAF from 1,3-benzylideneglycerol 3.1 [69].
Figure 4: A) Synthesis of the two enantiomers of octadecylglycerol (4.6 and 4.10) from ᴅ-mannitol (4.1); B) s...
Figure 5: Four-step synthesis of PAF 5.6 from (S)-glycidol [73].
Figure 6: Synthesis of 1-O-alkylglycerol A) from solketal, B) from ᴅ- or ʟ-tartaric acid and the intermediate ...
Figure 7: Synthesis of EL building blocks starting from substituted glycidol 7.1a–c [82].
Figure 8: Synthesis of PAF 8.5 by using phosphoramidite 8.2 [86].
Figure 9: Synthesis of oleyl-PAF 9.7 from ʟ-serine [88].
Figure 10: Synthesis of racemic analogues of lyso-PAF 10.8 and PAF 10.9 featuring a phenyl group between the g...
Figure 11: Synthesis of racemic deoxy-lyso-PAF 11.7 and deoxy-PAF 11.8 [91].
Figure 12: Synthesis of racemic thio-PAF 12.8 [93].
Figure 13: Racemic synthesis of 13.6 to illustrate the modification of the glycerol backbone by adding a methy...
Figure 14: Racemic synthesis of 14.5 as an illustration of the introduction of methyl substituents on the glyc...
Figure 15: Synthesis of functionalized sn-2-acyl chains of PC-EL; A) Steglich esterification or acylation reac...
Figure 16: Synthesis of racemic mc-PAF (16.3), a carbamate analogue of PAF [102].
Figure 17: A) Synthesis of (R)-17.2 and (S)-17.6 starting from (S)-solketal (17.1); B) synthesis of N3-PAF (17...
Figure 18: Modification of the phosphocholine polar head to produce PAF analogues [81].
Figure 19: Racemic PAF analogues 19.3 and 19.5 characterized by the absence of the phosphate group [107].
Figure 20: Synthesis of PIP3-PAF (20.7) [108].
Figure 21: Large-scale synthesis of C18-edelfosine (21.8) [116].
Figure 22: Synthesis of C16-edelfosine (22.10) starting from isopropylidene-ʟ-glyceric acid methyl ester (22.1...
Figure 23: Phosphocholine moiety installation by the use of chlorophosphite 23.2 as key reagent [119].
Figure 24: Synthesis of rac-1-alkyl-2-O-methylglycerol (AMG) [120].
Figure 25: Synthesis of stereocontrolled 1-alkyl-2-O-methyl glycerol 25.9 (AMG) from dimethyl ᴅ-tartrate [81].
Figure 26: A) Racemic synthesis of thioether 26.4 [129,130], B) structure of sulfone analogue 26.5 [129].
Figure 27: Stereocontrolled synthesis of C18-edelfosine thioether analogue 27.8 [118].
Figure 28: Synthesis of thioether 28.4 that include a thiophosphate function [134].
Figure 29: Synthesis of ammonium thioether 29.4 and 29.6 [135].
Figure 30: Synthesis of the N-methylamino analogue of edelfosine 30.6 (BN52211) [138].
Figure 31: Synthesis of 1-desoxy analogues of edelfosine; A) with a saturated alkyl chain; B) synthesis of the...
Figure 32: Stereocontrolled synthesis of edelfosine analogue (S)-32.8 featuring a C18:1 lipid chain [142].
Figure 33: Synthesis of edelfosine analogues with modulation of the lipid chain; A) illustration with the synt...
Figure 34: Synthesis of phospholipid featuring a carbamate function to link the lipid chain to the glycerol un...
Figure 35: Synthesis of sesquiterpene conjugates of phospho glycero ether lipids [148].
Figure 36: Racemic synthesis of methyl-substituted glycerol analogues 36.7 and 36.10: A) synthesis of diether ...
Figure 37: Racemic synthesis of ilmofosine (37.6) [155,156].
Figure 38: A) Stereoselective synthesis of 38.5 via a stereoselective hydroboration reaction; B) synthesis of ...
Figure 39: Racemic synthesis of SRI62-834 (39.6) featuring a spiro-tetrahydrofurane heterocycle in position 2 ...
Figure 40: Racemic synthesis of edelfosine analogue 40.5 featuring an imidazole moiety in sn-2 position [160].
Figure 41: Racemic synthesis of fluorine-functionalized EL: A) Synthesis of 41.6 and B) synthesis of 41.8 [161-163].
Figure 42: A) Synthesis of the β-keto-ester 42.6 that also features a decyl linker between the phosphate and t...
Figure 43: Synthesis of phosphonate-based ether lipids; A) edelfosine phosphonate analogue 43.7 and B) thioeth...
Figure 44: Enantioselective synthesis of phosphonates 44.3 and 44.4 [171].
Figure 45: Racemic synthesis of phosphinate-based ether lipid 45.10 [172].
Figure 46: Racemic synthesis of edelfosine arsonium analogue 46.5 [173].
Figure 47: Synthesis of edelfosine dimethylammonium analogue 47.2 [118].
Figure 48: Synthesis of rac-C18-edelfosine methylammonium analogue 48.4 [176].
Figure 49: A) Synthesis of edelfosine N-methylpyrrolidinium analogue 49.2 or N-methylmorpholinium analogue 49.3...
Figure 50: A) Synthesis of edelfosine’s analogue 50.4 with a PE polar group; B) illustration of a pyridinium d...
Figure 51: A) Synthesis of 51.4 featuring a thiazolium cationic moiety; B) synthesis of thiazolium-based EL 51...
Figure 52: Synthesis of cationic ether lipids 52.3, 52.4 and 52.6 [135,183].
Figure 53: Synthesis of cationic carbamate ether lipid 53.5 [184].
Figure 54: Synthesis of cationic sulfonamide 54.5 [185].
Figure 55: Chemical structure of ONO-6240 (55.1) and SRI-63-119 (55.2).
Figure 56: Synthesis of non-ionic ether lipids 56.2–56.9 [188].
Figure 57: Synthesis of ether lipid conjugated to foscarnet 57.6 [189].
Figure 58: A) Synthesis of ether lipid conjugated to arabinofuranosylcytosine; B) synthesis of AZT conjugated ...
Figure 59: Synthesis of quercetin conjugate to edelfosine [191].
Figure 60: Synthesis of 60.8 (Glc-PAF) [194].
Figure 61: A) Synthesis of amino ether lipid 61.7 functionalized with a rhamnose unit and its amide analogue 6...
Figure 62: A) Synthesis of glucose ether lipid 62.4; B) structure of ether lipid 62.5 possessing a maltose uni...
Figure 63: A) Synthesis of glucuronic methyl ester 63.8; B) structure of cellobiose 63.9 and maltose 63.10 ana...
Figure 64: A) Synthesis of maltosyl glycerolipid 64.7; B) structure of lactose analogue 64.8 prepared followin...
Figure 65: A) Asymmetric synthesis of the aglycone moiety starting from allyl 4-methoxyphenyl ether; B) glycos...
Figure 66: A) Synthesis of ohmline possessing a lactose moiety. B) Structure of other glyco glycero lipids pre...
Figure 67: A) Synthesis of lactose-glycerol ether lipid 67.5; B) analogues possessing a maltose (67.6) or meli...
Figure 68: Synthesis of digalactosyl EL 68.6, A) by using trityl, benzyl and acetyl protecting groups, B) by u...
Figure 69: A) Synthesis of α-ohmline; B) structure of disaccharide ether lipids prepared by using similar meth...
Figure 70: Synthesis of lactose ether lipid 70.3 and its analogue 70.6 featuring a carbamate function as linke...
Figure 71: Synthesis of rhamnopyranoside diether 71.4 [196].
Figure 72: Synthesis of 1-O-hexadecyl-2-O-methyl-3-S-(α-ᴅ-1'-thioglucopyranosyl)-sn-glycerol (72.5) [225].
Figure 73: A) Preparation of lipid intermediate 73.4; B) synthesis of 2-desoxy-C-glycoside 73.10 [226].
Figure 74: Synthesis of galactose-pyridinium salt 74.3 [228].
Figure 75: Synthesis of myo-inositol derivative Ino-C2-PAF (75.10) [230].
Figure 76: A) Synthesis of myo-inositol phosphate building block 76.7; B) synthesis of myo-inositolphosphate d...
Figure 77: A) Synthesis of phosphatidyl-3-desoxy-inositol 77.4; B) synthesis of phosphono-3-desoxyinositol 77.9...
Figure 78: A) Structure of diether phosphatidyl-myo-inositol-3,4-diphosphate 78.1; B) synthesis of phosphatidy...
Figure 79: A) Synthesis of diether-phosphatidyl derivative 79.4 featuring a hydroxymethyl group in place of a ...
Figure 80: Synthesis of Glc-amine-PAF [78].
Figure 81: Synthesis of glucosamine ether lipid 81.4 and its analogues functionalized in position 3 of the ami...
Figure 82: Synthesis of fully deprotected aminoglucoside ether lipid 82.5 [246].
Figure 83: Synthesis of C-aminoglycoside 83.12 using Ramberg–Bäcklund rearrangement as a key step [250].
Figure 84: A) List of the most important glyco lipids and amino glyco lipids included in the study of Arthur a...
Figure 85: Synthesis of mannosamine ether lipid 85.6 [254].
Figure 86: A) Synthesis of glucosamine ether lipids with a non-natural ʟ-glucosamine moiety; B) synthesis of e...
Figure 87: A) Structure of the most efficient anticancer agents 87.1–87.4 featuring a diamino glyco ether lipi...
Figure 88: A) Synthesis of diamino glyco ether lipid 87.4; B) synthesis of bis-glycosylated ether lipid 88.10 [256]....
Figure 89: Synthesis of triamino ether lipid 89.4 [260].
Figure 90: Synthesis of chlorambucil conjugate 90.7 [261].
Figure 91: Three main methods for the preparation of glycerol ether lipid 91.3; A) from solketal and via a tri...
Figure 92: Four different methods for the installation of the phosphocholine polar head group; A) method using...
Figure 93: Illustration of two methods for the installation of saccharides or aminosaccharides; A) O-glycosyla...
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
- Guthrie in the 1860s as an attraction between ammonia and molecular iodine [19]. The 20th century saw halogen bonding extended to organohalides such as diiodoacetylene [25][26], and also saw the first X-ray crystallographic evidence of a ‘halogen molecular bridge’ between molecular bromine and 1,4-dioxane
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
- enabling controlled bond activations [45]. Regarding the reductive C–C arylation, the application of the xanthene dye rhodamine 6G (Rh-6G) as a catalyst for the reduction of heteroarenes bearing two or three bromine atoms (e.g., 6) under irradiation with green light (λ = 530 nm) gave monosubstituted
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.
Bromination of endo-7-norbornene derivatives revisited: failure of a computational NMR method in elucidating the configuration of an organic structure
- Demet Demirci Gültekin,
- Arif Daştan,
- Yavuz Taşkesenligil,
- Cavit Kazaz,
- Yunus Zorlu and
- Metin Balci
Beilstein J. Org. Chem. 2023, 19, 764–770, doi:10.3762/bjoc.19.56
- for those ‘revised structures’ [3]. This paper impelled us to revisit our original work and assess the validity of Novitskiy and Kutateladze’s claim whether our assignment was indeed wrong. Results and Discussion In 2008 we investigated the electrophilic addition of bromine to 1 (7-endo-bicyclo[2.2.1
- elucidated the exact configuration of compound 6. The symmetrical structure of 6 could be characterized easily because of its four-line 13C NMR spectrum. However, on the basis of 13C NMR data alone we were not able to distinguish between possible symmetrical tribromides. The configurations of the bromine
- observation provides evidence that the H2 and H3 protons have the exo-configuration. In other words, the adjacent bromine atoms have the endo-configuration (Supporting Information File 1). Upon irradiation at the resonance frequency (4.97 ppm) of the protons H2 and H3 no change is observed in the resonance
Graphical Abstract
Scheme 1: Bromination of endo-7-bromonorbornene.
Figure 1: Structure 6 (our assignment) and structure 7 revised by Novitskiy and Kutateladze.
Figure 2: W or M orientaition in norbornane and the corresponding coupling constants.
Figure 3: The determined structure 6 by NMR experiments and the proposed structure 7 by computional NMR.
Figure 4: The normal and expanded 1H NMR spectra of compound 6.
Figure 5: γ-Gauche effects caused by bromine atoms in 3, 5, and 6.
Figure 6: NOE-Diff experiment. Double resonance experiment. Irradiation at the resonance frequency of protons...
Figure 7: NOE-Diff experiment. Irradiation at the resonance frequency of proton H7 (4.23 ppm).
Scheme 2: Our mechanism suggested for the formation of 6 [4].
Scheme 3: The mechanism suggested by Novitskiy and Kutateladze for the formation of 7 [3].
Figure 8: A) Molecular structure of the compound 6 with displacement ellipsoids drawn at the 30% probability ...
Improving the accuracy of 31P NMR chemical shift calculations by use of scaling methods
- William H. Hersh and
- Tsz-Yeung Chan
Beilstein J. Org. Chem. 2023, 19, 36–56, doi:10.3762/bjoc.19.4
Graphical Abstract
Figure 1: Training set of tri- and tetracoordinate phosphorus compounds; chemical shifts are in ppm, referenc...
Figure 2: (a) Plot of experimental vs calculated chemical shifts of tri- and tetracoordinate phosphorus compo...
Figure 3: Plot of experimental vs calculated chemical shifts of training set compounds reported by Latypov et...
Figure 4: “Large” compounds selected for 31P NMR calculation by Latypov [37].
Figure 5: Stereoisomers and unusual phosphorus compounds used for chemical shift calculations.
Figure 6: Phosphorus-catalyzed oxygen transfer reaction intermediates.
Figure 7: Phosphirane reactions.
Figure 8: (a) Plot of experimental vs scaled chemical shifts derived from the tri- and tetracoordinate phosph...
Redox-active molecules as organocatalysts for selective oxidative transformations – an unperceived organocatalysis field
- Elena R. Lopat’eva,
- Igor B. Krylov,
- Dmitry A. Lapshin and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2022, 18, 1672–1695, doi:10.3762/bjoc.18.179
- enantioselective hydroxylation of benzylic positions was achieved using a chiral aryl iodide mediator [148] (Scheme 34). At the first stage, under the action of m-CPBA and sodium bromide an active form of the catalyst ArI3-Br is formed, in which the iodine–bromine bond is cleaved homolytically under visible light
Graphical Abstract
Scheme 1: Organocatalysis classification used in the present perspective.
Scheme 2: Oxidative processes catalyzed by amines.
Scheme 3: N-Heterocyclic carbene (NHC) catalysis in oxidative functionalization of aldehydes.
Scheme 4: Examples of asymmetric oxidative processes catalyzed by chiral Brønsted acids.
Scheme 5: Asymmetric aerobic α-hydroxylation of lactams under phase-transfer organocatalysis conditions emplo...
Scheme 6: Selective CH-oxidation of methylarenes to aldehydes or carboxylic acids.
Scheme 7: An example of the regioselective CH-amination by a sterically hindered imide-N-oxyl radical precurs...
Scheme 8: CH-amination of ethylbenzene and CH-fluorination of aldehydes catalyzed by N-hydroxybenzimidazoles,...
Scheme 9: Mixed hetero-/homogeneous TiO2/N-hydroxyimide photocatalysis in the selective benzylic oxidation.
Scheme 10: Electrochemical benzylic iodination and benzylation of pyridine by benzyl iodides generated in situ...
Scheme 11: Electrochemical oxidative C–O/C–N coupling of alkylarenes with NHPI. Electrolysis conditions: Const...
Scheme 12: Chemoselective alcohol oxidation catalyzed by TEMPO.
Scheme 13: ABNO-catalyzed oxidative C–N coupling of primary alcohols with primary amines.
Scheme 14: ACT-catalyzed electrochemical oxidation of primary alcohols and aldehydes to carboxylic acids.
Scheme 15: Electrocatalytic oxidation of benzylic alcohols by a TEMPO derivative immobilized on a graphite ano...
Scheme 16: Electrochemical oxidation of carbamates of cyclic amines to lactams and oxidative cyanation of amin...
Scheme 17: Hydrogen atom transfer (HAT) and single-electron transfer (SET) as basic principles of amine cation...
Scheme 18: Electrochemical quinuclidine-catalyzed oxidation involving unactivated C–H bonds.
Scheme 19: DABCO-mediated photocatalytic C–C cross-coupling involving aldehyde C–H bond cleavage.
Scheme 20: DABCO-derived cationic catalysts in inactivated C–H bond cleavage for alkyl radical addition to ele...
Scheme 21: Electrochemical diamination and dioxygenation of vinylarenes catalyzed by triarylamines.
Scheme 22: Electrochemical benzylic oxidation mediated by triarylimidazoles.
Scheme 23: Thiyl radical-catalyzed CH-arylation of allylic substrates by aryl cyanides.
Scheme 24: Synthesis of redox-active alkyl tetrafluoropyridinyl sulfides by unactivated C–H bond cleavage by t...
Scheme 25: Main intermediates in quinone oxidative organocatalysis.
Scheme 26: Electrochemical DDQ-catalyzed intramolecular dehydrogenative aryl–aryl coupling.
Scheme 27: DDQ-mediated cross-dehydrogenative C–N coupling of benzylic substrates with azoles.
Scheme 28: Biomimetic o-quinone-catalyzed benzylic alcohol oxidation.
Scheme 29: Electrochemical synthesis of secondary amines by oxidative coupling of primary amines and benzylic ...
Scheme 30: General scheme of dioxirane and oxaziridine oxidative organocatalysis.
Scheme 31: Dioxirane organocatalyzed CH-hydroxylation involving aliphatic C(sp3)–H bonds.
Scheme 32: Enantioselective hydroxylation of CH-acids catalyzed by chiral oxaziridines.
Scheme 33: Iodoarene-organocatalyzed vinylarene diamination.
Scheme 34: Iodoarene-organocatalyzed asymmetric CH-hydroxylation of benzylic substrates.
Scheme 35: Iodoarene-organocatalyzed asymmetric difluorination of alkenes with migration of aryl or methyl gro...
Scheme 36: Examples of 1,2-diiodo-4,5-dimethoxybenzene-catalyzed electrochemical oxidative heterocyclizations.
Scheme 37: Electrochemical N-ammonium ylide-catalyzed CH-oxidation.
Scheme 38: Oxidative dimerization of aryl- and alkenylmagnesium compounds catalyzed by quinonediimines.
Scheme 39: FLP-catalyzed dehydrogenation of N-substituted indolines.
Simple synthesis of multi-halogenated alkenes from 2-bromo-2-chloro-1,1,1-trifluoroethane (halothane)
- Yukiko Karuo,
- Atsushi Tarui,
- Kazuyuki Sato,
- Kentaro Kawai and
- Masaaki Omote
Beilstein J. Org. Chem. 2022, 18, 1567–1574, doi:10.3762/bjoc.18.167
- Yukiko Karuo Atsushi Tarui Kazuyuki Sato Kentaro Kawai Masaaki Omote Faculty of Pharmaceutical Sciences, Setsunan University, 45-1 Nagaotoge-cho, Hirakata, Osaka 573-0101, Japan 10.3762/bjoc.18.167 Abstract A series of aryl fluoroalkenyl ethers that contain chlorine and bromine as well as
- difluoroalkyl ethers (1), along with small amounts of fluoroalkenyl ethers (2), which were obtained from 1 via an E2-elimination mechanism (Scheme 1B) [14][15]. The fluoroalkenyl group in 2 is a potentially useful moiety that could participate in cross-coupling reactions for replacement of the bromine atom with
- bond between the bromine and chlorine atoms in 1. Extra KOH was added to improve deprotonation, but the yield of 2a was still low (Table 1, entries 2 and 3). Changing the solvent from THF to DME and increasing the temperature to 80 °C slightly improved the yield of 2a to 19% (Table 1, entry 4
Graphical Abstract
Figure 1: Medicines containing a difluoromethylene group.
Scheme 1: Reaction of phenol with polyfluoroalkanes.
Figure 2: Fluoroalkene analogs of some drugs.
Scheme 2: Proposed mechanism.
Scheme 3: Sonogashira cross-coupling reaction of 2a with trimethylsilylacetylene.
Using UHPLC–MS profiling for the discovery of new sponge-derived metabolites and anthelmintic screening of the NatureBank bromotyrosine library
- Sasha Hayes,
- Aya C. Taki,
- Kah Yean Lum,
- Joseph J. Byrne,
- Merrick G. Ekins,
- Robin B. Gasser and
- Rohan A. Davis
Beilstein J. Org. Chem. 2022, 18, 1544–1552, doi:10.3762/bjoc.18.164
- time. 5-Debromopurealidin H (1) was isolated as a stable yellow film. The LRESIMS of 1 showed 1:1 ion cluster peaks at m/z 382/384 [M + H]+ and 380/382 [M − H]−, indicating the presence of one bromine atom [16]. Furthermore, a molecular formula of C14H17BrN5O3 was assigned following analysis of the 1D
- data with related previously reported purealidins [19]. While no HMBC correlations were identified for these exchangeable proton signals, the presence of a phenol was further supported by a bathochromic shift that was seen in the UV spectrum of 1 upon addition of base [20]. The bromine atom and phenol
Graphical Abstract
Figure 1: UHPLC–UV chromatogram (254 nm) of the CH2Cl2/MeOH extract of Ianthella basta (NB6021519); retention...
Figure 2: Chemical structures of 5-debromopurealidin H (1) and ianthesine E (2).
Figure 3: Key COSY, HMBC and ROESY correlations for 5-debromopurealidin H (1).
Figure 4: Chemical structures of the NatureBank bromotyrosine derivatives: psammaplysins F (3) and H (4), bas...
Figure 5: Dose-response assessment of in vitro activity of compounds 1–9 against exsheathed third-stage larva...
An alternative C–P cross-coupling route for the synthesis of novel V-shaped aryldiphosphonic acids
- Stephen J. I. Shearan,
- Enrico Andreoli and
- Marco Taddei
Beilstein J. Org. Chem. 2022, 18, 1518–1523, doi:10.3762/bjoc.18.160
- explains the high phosphite-to-bromine ratio, which in our case is higher than all the other routes, since the phosphite itself acts as the solvent as well as being a reactant. If this ratio was lower, there would be a considerable drop in the reaction rate towards the end and would likely lead to
Graphical Abstract
Scheme 1: Scheme showing the transformation of the Br-substrates to phosphonate esters and then to phosphonic...
Figure 1: Experimental setup for the improved C–P cross-coupling reaction.
Mechanochemical synthesis of unsymmetrical salens for the preparation of Co–salen complexes and their evaluation as catalysts for the synthesis of α-aryloxy alcohols via asymmetric phenolic kinetic resolution of terminal epoxides
- Shengli Zuo,
- Shuxiang Zheng,
- Jianjun Liu and
- Ang Zuo
Beilstein J. Org. Chem. 2022, 18, 1416–1423, doi:10.3762/bjoc.18.147
- due to the strong electron-withdrawing effect of bromine, enhancing the electrophilic property of bromo-substituted salicylaldehyde. Because of the poor solubility in the eluent, the yield of dichloro-containing 1c (88%) was lower than 1a after isolating by column chromatography. This was also found
Graphical Abstract
Figure 1: Representative asymmetric Co–salen catalysts.
Scheme 1: Synthetic approach to our unsymmetrical Co–salen catalyst 2f for the asymmetric synthesis of α-aryl...
Scheme 2: Mechanochemical one-pot two-step synthesis of unsymmetrical salens 1a–h. Reaction conditions: salic...
Scheme 3: Synthesis of unsymmetrical metal–salen complexes 2. Reaction conditions a: metal acetate hydrate (1...
Scope of tetrazolo[1,5-a]quinoxalines in CuAAC reactions for the synthesis of triazoloquinoxalines, imidazoloquinoxalines, and rhenium complexes thereof
- Laura Holzhauer,
- Chloé Liagre,
- Olaf Fuhr,
- Nicole Jung and
- Stefan Bräse
Beilstein J. Org. Chem. 2022, 18, 1088–1099, doi:10.3762/bjoc.18.111
- obtained products. Single crystals for complexes 27a–d were obtained via slow evaporation of a solution in either methylene chloride, ethyl acetate, or deuterated chloroform under ambient conditions. The rhenium atom is coordinated to three carbonyl groups, the bromine atom and two nitrogens of the 1,2,3
- crystal structure confirmed that rhenium is coordinated to three carbonyl groups, the bromine atom and two nitrogens of the 1,2,3-triazoloquinoxaline ligand. However, in this case, instead of coordination via the quinoxaline nitrogen and the 2-nitrogen of the triazole ring, the complex is formed via
- and one bromine atom (see Scheme 8). UV–vis absorption spectra of all obtained rhenium complexes (Figure 1) and those of the free ligands (Figure S4, Supporting Information File 1) were measured in acetonitrile. The molar extinction coefficients ε of the complexes were calculated from the obtained
Graphical Abstract
Scheme 1: Reactions of tetrazoloquinoxalines 1 to 1,2,3-triazoloquinoxalines 3 via CuAAC and denitrogenative ...
Scheme 2: Synthesis of tetrazolo[1,5-a]quinoxalines. Reaction conditions: (a) 9, THF or 4 M HCl, 70–110 °C, 2...
Scheme 3: Synthesis of 1,2,3-triazole-substituted quinoxalines via CuAAC from tetrazolo[1,5-a]quinoxaline (11a...
Scheme 4: Mechanism of CuAAC vs denitrogenative annulation.
Scheme 5: Synthesis of bis(tetrazolo)[1,5-a:5',1'-c]quinoxaline (24) and conversion to triazoloimidazoquinoxa...
Scheme 6: Synthesis of rhenium tricarbonyl complexes 27a–d and ORTEP diagrams of the resulting molecular stru...
Scheme 7: Synthesis of rhenium tricarbonyl complex 29 and ORTEP diagram of the resulting molecular structure ...
Scheme 8: Synthesis of a TIQ rhenium complex and ORTEP diagram of the obtained product 30 with the thermal el...
Figure 1: UV–vis absorption spectra of the obtained metal complexes (18 µM solutions) in acetonitrile at 20 °...
Figure 2: Cyclic voltammetry traces for rhenium complexes 27a–d, 29 and 30: 0.5 mM in MeCN solution with 0.1 ...
Thiophene/selenophene-based S-shaped double helicenes: regioselective synthesis and structures
- Mengjie Wang,
- Lanping Dang,
- Wan Xu,
- Zhiying Ma,
- Liuliu Shao,
- Guangxia Wang,
- Chunli Li and
- Hua Wang
Beilstein J. Org. Chem. 2022, 18, 809–817, doi:10.3762/bjoc.18.81
- )2-bb-DSS), from which the TMS group could easily be removed by trifluoroacetic acid and replaced by bromine [27]. Another isomer of DSS, diseleno[3,2-b:2′,3′-d]selenophene (tt-DSS) has been successively synthesized from selenophene [28][29]. Among the limited fused aromatic compounds containing
Graphical Abstract
Figure 1: Molecular structures of bull horn-shaped heteroacene 1, selenophene-based [7]helicene 2 and novel c...
Scheme 1: Synthetic route to S-shaped double helicenes DH-1–3.
Figure 2: Five kinds of isomer structures of 5 and two kinds of possible oxidative photocyclization product s...
Figure 3: Molecular structures and side view for DH-1 and DH-2. A and B are molecular structures for DH-1 and ...
Figure 4: UV–vis absorption spectra of DH-1–3 in CH2Cl2 ([c] = 1 × 10−5 M).
Synthesis of odorants in flow and their applications in perfumery
- Merlin Kleoff,
- Paul Kiler and
- Philipp Heretsch
Beilstein J. Org. Chem. 2022, 18, 754–768, doi:10.3762/bjoc.18.76
- achieved within milliseconds initializing bromine–lithium exchange of bromochloromethane to generate (chloromethyl)lithium. This carbenoid species readily reacts with terpenyl pinacol boronates 17, resulting in the formation of intermediate 18, which undergoes 1,2-anionotropic rearrangement to the
Graphical Abstract
Figure 1: The olfactory spectrum wheel ordering different types of odorants from fruity to musky.
Figure 2: Classification of odorants as “top note”, “middle note” and “base note” depending on their substant...
Scheme 1: Synthesis of raspberry ketone (5) and raspberry ketone methyl ether (6) in two steps in flow.
Scheme 2: Autoxidation of (+)-valencene (7) to (+)-nootkatone (8) under catalyst and solvent-free conditions ...
Scheme 3: Enzyme-catalyzed acetylation of isoamyl alcohol (9) in a biphasic n-heptane/water mixture utilizing...
Scheme 4: Esterification of alcohols by transesterification, catalyzed by immobilized acyltransferase in a pa...
Scheme 5: Synthesis of homologated alcohols 20 by iterative homologation of terpenyl boronate esters 17 follo...
Scheme 6: Sequential three-step synthesis of (S)-α-phellandrene (30) from (R)-carvone (25) via selective hydr...
Scheme 7: Selective hydrogenation of alkyne 31 to “leaf alcohol” 32 employing a solid-supported palladium cat...
Scheme 8: A) Synthesis of jasmonal (35) by crossed aldol condensation of benzaldehyde (33) and heptanal (34) ...
Scheme 9: Synthesis of thymol (41) from m-cresol (39) and isopropyl alcohol via Fries-type rearrangement of e...
Scheme 10: Preparation of coumarin (46) by reaction of salicylaldehyde (44) with potassium acetate, acetic aci...
Scheme 11: Synthesis of phthalide (50) by photoinduced decatungstate catalysis.
Scheme 12: Synthesis of woody acetate (54) by reduction of cyclohexanone 51 and subsequent acetylation; ADH200...
Scheme 13: Synthesis of juniper lactone (56) by pyrolysis of triperoxide 55 generated by oxidation of cyclohex...
Scheme 14: Synthesis of macrocyclic olefine 60 by ring-closing metathesis of diene 58 in a continuously stirre...
Scheme 15: Synthesis of macrocycles 65 and 66 by ring-closing metathesis of dienes 62 or 63, respectively, in ...
Scheme 16: Z-Selective synthesis of civetone (69) enabled by metathesis catalyst 68 in a tube-in-tube reactor.
Scheme 17: Synthesis of macrocyclic olefine 72 by ring-closing metathesis of diene 70.
Mechanochemical halogenation of unsymmetrically substituted azobenzenes
- Dajana Barišić,
- Mario Pajić,
- Ivan Halasz,
- Darko Babić and
- Manda Ćurić
Beilstein J. Org. Chem. 2022, 18, 680–687, doi:10.3762/bjoc.18.69
- four mechanistic pathways could be involved in this reaction [51]. Three of them involve oxidative addition followed by reductive elimination. Neutral NBS or the hydrogen bond complex NBS∙∙∙TsOH are bromine donors in two of them, while protonated NBS is engaged in the third. The fourth mechanism
- proceeds by electrophilic cleavage with neutral NBS or the hydrogen bond complex NBS∙∙∙TsOH as a bromine source. Here we present the mechanochemical selective halogenation of unsymmetrically substituted azobenzenes by NXS (X = Cl, Br, or I). The liquid-assisted grinding of para-halogenated derivatives of
Graphical Abstract
Figure 1: Molecular structures of the monomeric cyclopalladated intermediate and brominated product observed ...
Scheme 1: Halogenation of azobenzenes with strong electron-donating substituents.
Figure 2: a) Two-dimensional (2D) plot of the time-resolved Raman monitoring of NG of L2 (0.50 mmol) with NBS...
Figure 3: Experimental X-ray molecular structure of succinimide product L4-III.
Scheme 2: PdII-catalyzed halogenation of azobenzene and its para-halogenated derivatives.
Figure 4: Experimental X-ray molecular structure of the intermediate I6-I.
Figure 5: a) In situ observation of I6-I during the time-resolved Raman monitoring of LAG of L6 (0.50 mmol) w...
Menadione: a platform and a target to valuable compounds synthesis
- Acácio S. de Souza,
- Ruan Carlos B. Ribeiro,
- Dora C. S. Costa,
- Fernanda P. Pauli,
- David R. Pinho,
- Matheus G. de Moraes,
- Fernando de C. da Silva,
- Luana da S. M. Forezi and
- Vitor F. Ferreira
Beilstein J. Org. Chem. 2022, 18, 381–419, doi:10.3762/bjoc.18.43
- menadione (10), as was demonstrated by Minisci and co-workers [66]. In this work, the oxidation of 17 with 60% aqueous hydrogen peroxide, using bromine and sulfuric acid as catalysts, provided menadione in 90% yield (Table 2, entry 1) [66]. According to the proposed mechanism, the first step involves the
- by treating menadione (10) with molecular bromine in the presence of sodium acetate and acetic acid in 76% yield. With brominated compound 82 at hands, the authors obtained four menadione derivatives 83a–d functionalized with organochalcogenic moieties after treatment of compound 82 with the
Graphical Abstract
Figure 1: Natural bioactive naphthoquinones.
Figure 2: Chemical structures of vitamins K.
Figure 3: Redox cycle of menadione.
Scheme 1: Selected approaches for menadione synthesis using silver(I) as a catalyst.
Scheme 2: Methylation approaches for the preparation of menadione from 1,4-naphthoquinone using tert-butyl hy...
Scheme 3: Methylation approach of 1,4-naphthoquinone using i) rhodium complexes/methylboronic acid and ii) bi...
Scheme 4: Synthesis of menadione (10) from itaconic acid.
Scheme 5: Menadione synthesis via Diels–Alder reaction.
Scheme 6: Synthesis of menadione (10) using p-cresol as a synthetic precursor.
Scheme 7: Synthesis of menadione (10) via demethoxycarbonylating annulation of methyl methacrylate.
Scheme 8: Furan 34 used as a diene in a Diels–Alder reaction for the synthesis of menadione (10).
Scheme 9: o-Toluidine as a dienophile in a Diels–Alder reaction for the synthesis of menadione (10).
Scheme 10: Representation of electrochemical synthesis of menadione.
Figure 4: Reaction sites and reaction types of menadione as substrate.
Scheme 11: DBU-catalyzed epoxidation of menadione (10).
Scheme 12: Phase-transfer catalysis for the epoxidation of menadione.
Scheme 13: Menadione epoxidation using a hydroperoxide derived from (+)-norcamphor.
Scheme 14: Enantioselective Diels–Alder reaction for the synthesis of asymmetric quinone 50 catalyzed by a chi...
Scheme 15: Optimized reaction conditions for the synthesis of anthra[9,1-bc]pyranone.
Scheme 16: Synthesis of anthra[9,1-bc]furanone, anthra[9,1-bc]pyridine, and anthra[9,1-bc]pyrrole derivatives.
Scheme 17: Synthesis of derivatives employing protected trienes.
Scheme 18: Synthesis of cyclobutene derivatives of menadione.
Scheme 19: Menadione reduction reactions using sodium hydrosulfite.
Scheme 20: Green methodology for menadiol synthesis and pegylation.
Scheme 21: Menadione reduction by 5,6-O-isopropylidene-ʟ-ascorbic acid under UV light irradiation.
Scheme 22: Selected approaches of menadione hydroacetylation to diacetylated menadiol.
Scheme 23: Thiele–Winter reaction catalyzed by Bi(OTf)3.
Scheme 24: Carbonyl condensation of menadione using resorcinol and a hydrazone derivative.
Scheme 25: Condensation reaction of menadione with thiosemicarbazide.
Scheme 26: Condensation reaction of menadione with acylhydrazides.
Scheme 27: Menadione derivatives functionalized with organochalcogens.
Scheme 28: Synthesis of selenium-menadione conjugates derived from chloromethylated menadione 84.
Scheme 29: Menadione alkylation by the Kochi–Anderson method.
Scheme 30: Menadione alkylation by diacids.
Scheme 31: Menadione alkylation by heterocycles-substituted carboxylic acids.
Scheme 32: Menadione alkylation by bromoalkyl-substituted carboxylic acids.
Scheme 33: Menadione alkylation by complex carboxylic acids.
Scheme 34: Kochi–Anderson method variations for the menadione alkylation via oxidative decarboxylation of carb...
Scheme 35: Copper-catalyzed menadione alkylation via free radicals.
Scheme 36: Nickel-catalyzed menadione cyanoalkylation.
Scheme 37: Iron-catalyzed alkylation of menadione.
Scheme 38: Selected approaches to menadione alkylation.
Scheme 39: Menadione acylation by photo-Friedel–Crafts acylation reported by Waske and co-workers.
Scheme 40: Menadione acylation by Westwood procedure.
Scheme 41: Synthesis of 3-benzoylmenadione via metal-free TBAI/TBHP system.
Scheme 42: Michael-type addition of amines to menadione reported by Kallmayer.
Scheme 43: Synthesis of amino-menadione derivatives using polyalkylamines.
Scheme 44: Selected examples for the synthesis of different amino-substituted menadione derivatives.
Scheme 45: Selected examples of Michael-type addition of complex amines to menadione (10).
Scheme 46: Addition of different natural α-amino acids to menadione.
Scheme 47: Michael-type addition of amines to menadione using silica-supported perchloric acid.
Scheme 48: Indolylnaphthoquinone or indolylnaphthalene-1,4-diol synthesis reported by Yadav et al.
Scheme 49: Indolylnaphthoquinone synthesis reported by Tanoue and co-workers.
Scheme 50: Indolylnaphthoquinone synthesis from menadione by Escobeto-González and co-workers.
Scheme 51: Synthesis of menadione analogues functionalized with thiols.
Scheme 52: Synthesis of menadione-derived symmetrical derivatives through reaction with dithiols.
Scheme 53: Mercaptoalkyl acids as nucleophiles in Michael-type addition reaction to menadione.
Scheme 54: Reactions of menadione (10) with cysteine derivatives for the synthesis of quinoproteins.
Scheme 55: Synthesis of menadione-glutathione conjugate 152 by Michael-type addition.
Ready access to 7,8-dihydroindolo[2,3-d][1]benzazepine-6(5H)-one scaffold and analogues via early-stage Fischer ring-closure reaction
- Irina Kuznetcova,
- Felix Bacher,
- Daniel Vegh,
- Hsiang-Yu Chuang and
- Vladimir B. Arion
Beilstein J. Org. Chem. 2022, 18, 143–151, doi:10.3762/bjoc.18.15
- the nitro group but also to cyclization and the reductive elimination of bromine to afford 3a. The synthesis of 3b could be realized in 58% yield by using iron powder under acidic conditions. Reaction of methyl 5-(2-nitrophenyl)-4-oxopentanoate [44] and 1-benzyl-1-phenylhydrazine [36] hydrochloride in
Graphical Abstract
Figure 1: Paullone related indolobenzazepinone isomers. 7,12-Dihydroindolo[3,2-d][1]benzazepin-6(5H)-one or p...
Scheme 1: Investigated retrosynthetic pathways to scaffold C.
Scheme 2: Attempted synthesis of scaffold C by route (a).
Scheme 3: Attempted synthesis of C by route (b).
Scheme 4: Attempted synthesis of N-benzylated indole-2-acetic acid.
Scheme 5: Attempt to obtain open-chain precursor N-(2-bromophenyl)-2-(1H-indol-2-yl)acetamide.
Scheme 6: Synthesis of scaffold C and analogues by route (c).
Figure 2: ORTEP view of 1a with thermal ellipsoids drawn at the 50% probability level.
Figure 3: ORTEP view of 3a with thermal ellipsoids drawn at the 50% probability level.
Scheme 7: Attempted Ullmann cross-coupling of 23 with o-bromo-nitrobenzene.
DABCO-promoted photocatalytic C–H functionalization of aldehydes
- Bruno Maia da Silva Santos,
- Mariana dos Santos Dupim,
- Cauê Paula de Souza,
- Thiago Messias Cardozo and
- Fernanda Gadini Finelli
Beilstein J. Org. Chem. 2021, 17, 2959–2967, doi:10.3762/bjoc.17.205
- ). Surprisingly, decent amounts of product were observed when the reaction was performed without the use of DABCO (Table 1, entry 9). This result indicates an alternative mechanism can be possible for aryl ketone formation when there are no bicyclic amines in the reaction media. Recent works indicate a bromine
- addition experiment with methyl acrylate (Supporting Information File 1, Table S5), along with the strong dependence of aryl bromide electronics on the yield indicate the protagonism of the nickel-aryl bromide system. We hypothesized a HAT step by the bromine radical, generated by nickel complex photolysis
- , in a similar fashion of previous reports [31][32]. However, addition of bromide from external sources led to diminished yields (Supporting Information File 1, Table S6). Also, DFT calculations demonstrated that a HAT reaction between bromine radical and isovaleraldehyde is a barrierless reaction
Graphical Abstract
Figure 1: Redox potentials of representative nitrogenated HAT catalysts and photocatalysts [9-12,21-23].
Figure 2: Previous reports of DABCO as hydrogen abstractor in HAT reactions and this work.
Scheme 1: Aryl bromide and aldehyde scope. Isolated yields. aYield determined by 1H NMR analysis with 1,3-ben...
Scheme 2: Mechanistic investigations of the HAT reaction using DABCO.
Scheme 3: Proposed mechanism for aldehyde arylation. PC = photocatalyst Ir[dF(CF3)ppy]2(dtbbpy)PF6. SET = sin...
Figure 3: Free energy profile for the HAT step reactions between isovaleraldehyde with (top) DABCO and (botto...
Figure 4: TS structure for the HAT reaction between the DABCO radical cation and isovaleraldehyde obtained at...
A two-phase bromination process using tetraalkylammonium hydroxide for the practical synthesis of α-bromolactones from lactones
- Yuki Yamamoto,
- Akihiro Tabuchi,
- Kazumi Hosono,
- Takanori Ochi,
- Kento Yamazaki,
- Shintaro Kodama,
- Akihiro Nomoto and
- Akiya Ogawa
Beilstein J. Org. Chem. 2021, 17, 2906–2914, doi:10.3762/bjoc.17.198
- , and bromolactones are important synthetic intermediates for selectively, effectively, and practically introducing lactone units into organic molecules [1][2][3][4][5][6][7][8][9][10][11][12][13][14][15][16][17][18]. Among brominated lactones, the α-bromolactone, in which the bromine atom is located at
- reaction with bromine (Scheme 1a) [37][38]. While the industrial demand for α-bromolactones has grown in recent years, the above-mentioned laboratory-level synthetic methods are not suitable for scale-up because LDA, TMSCl, and enol silyl ethers are sensitive to moisture and air, as well as being expensive
Graphical Abstract
Scheme 1: General procedure for α-bromination of δ-valerolactone (1a) and the method described in this work.
Scheme 2: Tetraalkylammonium salt-mediated intramolecular cyclization of 2a.
Scheme 3: Synthesis of α-functionalized lactones using the two-phase system.
Scheme 4: Synthesis of unsymmetrically functionalized sulfide 5 via the two-phase system-promoted intramolecu...
Scheme 5: Sequential nucleophilic substitution in the two-phase system.
Scheme 6: One-pot synthesis of 2-phenylthio-α-valerolactone 6.
Synthetic strategies toward 1,3-oxathiolane nucleoside analogues
- Umesh P. Aher,
- Dhananjai Srivastava,
- Girij P. Singh and
- Jayashree B. S
Beilstein J. Org. Chem. 2021, 17, 2680–2715, doi:10.3762/bjoc.17.182
Graphical Abstract
Figure 1: Representative modified 1,3-oxathiolane nucleoside analogues.
Figure 2: Mechanism of antiviral action of 1,3-oxathiolane nucleosides, 3TC (1) and FTC (2), as chain termina...
Figure 3: Synthetic strategies for the construction of the 1,3-oxathiolane sugar ring.
Scheme 1: Synthesis of 4 from benzoyloxyacetaldehyde (3a) and 2-mercapto-substituted dimethyl acetal 3na.
Scheme 2: Synthesis of 8 from protected glycolic aldehyde 3b and 2-mercaptoacetic acid (3o).
Scheme 3: Synthesis of 20 from ᴅ-mannose (3c).
Scheme 4: Synthesis of 20 from 1,6-thioanhydro-ᴅ-galactose (3d).
Scheme 5: Synthesis of 8 from 2-(tert-butyldiphenylsilyloxy)methyl-5-oxo-1,2-oxathiolane (3m).
Scheme 6: Synthesis of 20a from ʟ-gulose derivative 3f.
Scheme 7: Synthesis of 31 from (+)-thiolactic acid 3p and 2-benzoyloxyacetaldehyde (3a).
Scheme 8: Synthesis of 35a from 1,4-dithiane-2,5-diol (3q) and glyoxylic acid (3g) hydrate.
Scheme 9: Synthetic routes toward 41 through Pummerer reaction from methyl 2-mercaptoacetate (3j) and bromoac...
Scheme 10: Strategy for the synthesis of 2,5-substituted 1,3-oxathiolane 41a using 4-nitrobenzyl glyoxylate an...
Scheme 11: Synthesis of 44 by a resolution method using Mucor miehei lipase.
Scheme 12: Synthesis of 45 from benzoyloxyacetaldehyde (3a) and 2-mercaptoacetaldehyde bis(2-methoxyethyl) ace...
Scheme 13: Synthesis of 46 from 2-mercaptoacetaldehyde bis(2-methoxyethyl) acetal (3nc) and diethyl 3-phosphon...
Scheme 14: Synthesis of 48 from 1,3-dihydroxyacetone dimer 3l.
Scheme 15: Approach toward 52 from protected alkene 3rb and lactic acid derivative 51 developed by Snead et al....
Scheme 16: Recent approach toward 56a developed by Kashinath et al.
Scheme 17: Synthesis of 56a from ʟ-menthyl glyoxylate (3h) hydrate by DKR.
Scheme 18: Possible mechanism with catalytic TEA for rapid interconversion of isomers.
Scheme 19: Synthesis of 35a by a classical resolution method through norephedrine salt 58 formation.
Scheme 20: Synthesis of 63 via [1,2]-Brook rearrangement from silyl glyoxylate 61 and thiol 3nb.
Scheme 21: Combined use of STS and CAL-B as catalysts to synthesize an enantiopure oxathiolane precursor 65.
Scheme 22: Synthesis of 1 and 1a from glycolaldehyde dimer 64 and 1,4-dithiane-2,5-diol (3q) using STS and CAL...
Scheme 23: Synthesis of 68 by using Klebsiella oxytoca.
Scheme 24: Synthesis of 71 and 72 using Trichosporon taibachii lipase and kinetic resolution.
Scheme 25: Synthesis of 1,3-oxathiolan-5-ones 77 and 78 via dynamic covalent kinetic resolution.
Figure 4: Pathway for glycosidic bond formation.
Scheme 26: First synthesis of (±)-BCH-189 (1c) by Belleau et al.
Scheme 27: Enantioselective synthesis of 3TC (1).
Scheme 28: Synthesis of cis-diastereomer 3TC (1) from oxathiolane propionate 44.
Scheme 29: Synthesis of (±)-BCH-189 (1c) via SnCl4-mediated N-glycosylation of 8.
Scheme 30: Synthesis of (+)-BCH-189 (1a) via TMSOTf-mediated N-glycosylation of 20.
Scheme 31: Synthesis of 3TC (1) from oxathiolane precursor 20a.
Scheme 32: Synthesis of 83 via N-glycosylation of 20 with pyrimidine bases.
Scheme 33: Synthesis of 85 via N-glycosylation of 20 with purine bases.
Scheme 34: Synthesis of 86 and 87 via N-glycosylation using TMSOTf and pyrimidines.
Scheme 35: Synthesis of 90 and 91 via N-glycosylation using TMSOTf and purines.
Scheme 36: Synthesis of 3TC (1) via TMSI-mediated N-glycosylation.
Scheme 37: Stereoselective N-glycosylation for the synthesis of 1 by anchimeric assistance of a chiral auxilia...
Scheme 38: Whitehead and co-workers’ approach for the synthesis of 1 via direct N-glycosylation without an act...
Scheme 39: ZrCl4-mediated stereoselective N-glycosylation.
Scheme 40: Plausible reaction mechanism for stereoselective N-glycosylation using ZrCl4.
Scheme 41: Synthesis of enantiomerically pure oxathiolane nucleosides 1 and 2.
Scheme 42: Synthesis of tetrazole analogues of 1,3-oxathiolane nucleosides 97.
Scheme 43: Synthetic approach toward 99 from 1,3-oxathiolane 45 by Camplo et al.
Scheme 44: Synthesis of 100 from oxathiolane phosphonate analogue 46.
Scheme 45: Synthetic approach toward 102 and the corresponding cyclic thianucleoside monophosphate 102a by Cha...
Scheme 46: Synthesis of emtricitabine (2) from 1,4-dithiane-2,5-diol (3q) and glyoxylic acid (3g).
Scheme 47: Synthesis of 1 and 2, respectively, from 56a–d using iodine-mediated N-glycosylation.
Scheme 48: Plausible mechanism for silane- and I2-mediated N-glycosylation.
Scheme 49: Pyridinium triflate-mediated N-glycosylation of 35a.
Scheme 50: Possible pathway for stereoselective N-glycosylation via in situ chelation with a metal ligand.
Scheme 51: Synthesis of novel 1,3-oxathiolane nucleoside 108 from oxathiolane precursor 8 and 3-benzyloxy-2-me...
Scheme 52: Synthesis of 110 using T-705 as a nucleobase and 1,3-oxathiolane derivative 8 via N-glycosylation.
Scheme 53: Synthesis of 1 using an asymmetric leaving group and N-glycosylation with bromine and mesitylene.
Scheme 54: Cytidine deaminase for enzymatic separation of 1c.
Scheme 55: Enzymatic resolution of the monophosphate derivative 116 for the synthesis of (−)-BCH-189 (1) and (...
Scheme 56: Enantioselective resolution by PLE-mediated hydrolysis to obtain FTC (2).
Scheme 57: (+)-Menthyl chloroformate as a resolving agent to separate a racemic mixture 120.
Scheme 58: Separation of racemic mixture 1c by cocrystal 123 formation with (S)-(−)-BINOL.
Synthesis and investigation on optical and electrochemical properties of 2,4-diaryl-9-chloro-5,6,7,8-tetrahydroacridines
- Najeh Tka,
- Mohamed Adnene Hadj Ayed,
- Mourad Ben Braiek,
- Mahjoub Jabli and
- Peter Langer
Beilstein J. Org. Chem. 2021, 17, 2450–2461, doi:10.3762/bjoc.17.162
- -5,6,7,8-tetrahydroacridine (4a) (Table 1, entries 1–6). Towards a better understanding of the regioselectivity of the coupling, we carried out a series of experiments with decreased amounts of phenylboronic acid. In all cases, the cross-coupling took place at both bromine atoms of 4a and we could never
Graphical Abstract
Figure 1: Some important tetrahydroacridines used as drugs.
Scheme 1: Synthesis of 2.
Scheme 2: Synthesis of compounds 4a–g.
Figure 2: UV–vis absorption spectra of 4a–d at room temperature in dilute dichloromethane solutions (c = 1 × ...
Figure 3: Fluorescence spectra of 4a–d at room temperature in dilute dichloromethane solutions (c = 1 × 10−5 ...
Figure 4: A) Absorbance and B) emission spectra for the standard quinine sulfate (SQ).
Figure 5: A) Absorbance and B) fluorescence spectra for 4b.
Figure 6: A) Plot of fluorescence intensities against their absorbances for quinine sulfate (SQ) and B) plot ...
Figure 7: Selected dihedral angles (°) for compounds 4a–d.
Figure 8: Selected dihedral angles (°) for compound 4f.
Figure 9: Calculated energy levels for compounds 4a–d and their spatial distribution of the HOMO–LUMO frontie...
Figure 10: Visualization of MEP for compounds 4a–d calculated by B3LYP method with 6-31G(d) basis set.
Figure 11: Cyclic voltammogram for 4c in 0.1 M (n-Bu)4NBF4/acetonitrile at a scan rate of 50 mV/s.
Enantioselective PCCP Brønsted acid-catalyzed aminalization of aldehydes
- Martin Kamlar,
- Robert Reiberger,
- Martin Nigríni,
- Ivana Císařová and
- Jan Veselý
Beilstein J. Org. Chem. 2021, 17, 2433–2440, doi:10.3762/bjoc.17.160
- crystallization from ethyl acetate. This was demonstrated for products 3a and 3f, that were obtained in enantiomeric purities of 93% and 97% ee, respectively (Scheme 1). Next, we turned our attention to the substitution of anthranilamide (Scheme 2). First, the effect of bromine as a slightly electron-withdrawing
- substituent on the aromatic ring was investigated. The position of bromine on the aromatic ring had a dramatic effect on the enantiomeric purity of the formed products 3k–n. When a bromine substituent is introduced in the “3” position of anthranilamide, the enantiomeric enrichment of aminal 3k reached only 30
- % ee. In contrast, substitution with bromine either in position “4” and “5” led to a formation of products 3l and 3m with enantiomeric purities of 70% ee and 80% ee, respectively. Finally, reaction with anthranilamide substituted with bromine in position “6” led to corresponding aminal 3n with an
Graphical Abstract
Figure 1: Synthetic strategies employing chiral Brønsted acid catalysis.
Scheme 1: The substrate scope of the aminalization reaction for different aldehydes. aAfter recrystallization...
Scheme 2: The substrate scope of the intermolecular aminalization reaction for anthranilamide derivatives. aA...
Figure 2: X-ray single-crystal structure of aminal 3l with the displacement ellipsoids drawn at the 30% proba...
A novel methodology for the efficient synthesis of 3-monohalooxindoles by acidolysis of 3-phosphate-substituted oxindoles with haloid acids
- Li Liu,
- Yue Li,
- Tiao Huang,
- Dulin Kong and
- Mingshu Wu
Beilstein J. Org. Chem. 2021, 17, 2321–2328, doi:10.3762/bjoc.17.150
- order to further extend the substrate scope, we tried using hydrobromic acid (40%) as a bromine source in the reaction, and the results are summarized in Scheme 3. Generally, the phosphate substrates 2 substituted with electron-donating substituents were more reactive than those with electron
Graphical Abstract
Figure 1: Representation of bioactive molecules and applications.
Scheme 1: Synthetic methodologies for 3-monohalooxindoles.
Scheme 2: Substrate scope of the acidolysis of isatin-derived phosphates 2 with hydrochloric acid. Standard r...
Scheme 3: Substrate scope of the acidolysis of isatin-derived phosphates 2 with hydrobromic acid. Standard re...
Scheme 4: Reduction of the substrates 2 to the corresponding oxindoles 5.
Scheme 5: Plausible reaction mechanism.
Halides as versatile anions in asymmetric anion-binding organocatalysis
- Lukas Schifferer,
- Martin Stinglhamer,
- Kirandeep Kaur and
- Olga García Macheño
Beilstein J. Org. Chem. 2021, 17, 2270–2286, doi:10.3762/bjoc.17.145
- oxycarbenium ion, which enables high enantioselectivities up to 95% ee and yields up to 91%. Furthermore, an investigation of the involved halide counter-anion revealed that chloride was the most potent one in regards of both yield and enantioinduction. Bromine and iodine on the other hand, afforded the final
Graphical Abstract
Figure 1: a) Binding interactions in the chloride channel of E. coli. and b) examples of chloride, cyanide, n...
Figure 2: a) H-bond vs anion-binding catalysis and b) activation modes in anion-binding catalysis.
Scheme 1: First proposed anion-binding mechanism in the thiourea-catalyzed acetalization of benzaldehyde.
Scheme 2: a) Thiourea-catalyzed enantioselective acyl-Pictet–Spengler reaction of tryptamine-derived imines 4...
Scheme 3: Proposed mechanism of the thiourea-catalyzed enantioselective Pictet–Spengler reaction of hydroxyla...
Scheme 4: a) Thiourea-catalyzed intramolecular Pictet–Spengler-type cyclization of hydroxylactam-derived N-ac...
Scheme 5: Enantioselective Reissert-type reactions of a) (iso)quinolines with silyl ketene acetals, and b) vi...
Figure 3: Role of the counter-anion: a) Anion acting as a spectator and b) anion participating directly as th...
Scheme 6: Enantioselective selenocyclization catalyzed by squaramide 28.
Scheme 7: Desymmetrization of meso-aziridines catalyzed by bifunctional thiourea catalyst 31.
Scheme 8: Anion-binding-catalyzed desymmetrization of a) meso-aziridines catalyzed by chiral triazolium catal...
Scheme 9: Bis-urea-catalyzed enantioselective fluorination of a) β-bromosulfides and b) β-haloamines by Gouve...
Scheme 10: a) Bifunctional thiourea anion-binding – basic/nucleophilic catalysts. Selected applications in b) ...
Scheme 11: Thiourea-catalyzed enantioselective polycyclization reaction of hydroxylactams 51 through cation–π ...
Scheme 12: Enantioselective aza-Sakurai cyclization of hydroxylactams 56 implicating additional cation–π and L...
Scheme 13: Enantioselective tail-to-head cyclization of neryl chloride derivatives.
Scheme 14: Cation–π interactions in anion binding-catalyzed asymmetric addition reactions: a) addition of indo...
Scheme 15: Bisthiourea catalyzed oxa-Pictet–Spengler reaction of indole-based alcohols and aromatic aldehydes ...
Scheme 16: Anion-binding catalyst development in the enantioselective addition of silyl ketene acetals to 1-ch...
Scheme 17: a) Macrocyclic bis-thiourea catalyst in a diastereoselective glycosylation reaction. b) Competing SN...
Scheme 18: a) Folding mechanism of oligotriazoles upon anion recognition. b) Representative tetratriazole 82 c...
Scheme 19: Switchable chiral tetratriazole catalyst 86 in the enantioselective addition of silyl ketene acetal...
Photoredox catalysis in nickel-catalyzed C–H functionalization
- Lusina Mantry,
- Rajaram Maayuri,
- Vikash Kumar and
- Parthasarathy Gandeepan
Beilstein J. Org. Chem. 2021, 17, 2209–2259, doi:10.3762/bjoc.17.143
- ]. Homolysis of the excited nickel(II) species 7-V results in the formation of a bromine radical, which then readily abstracts the allylic C(sp3)‒H to give the allylic radical species. Thus, the generated allylic radical species rebound to nickel complex and followed by reductive elimination delivers the
- enantioselectivities. A wide range of aryl bromides 3 were tested with alkylbenzenes 25 under ambient reaction conditions and afforded the desired products 26 in moderate yields and good enantioselectivities. Based on their control experiments and mechanistic studies, it was postulated that a bromine radical might be
- ]. Notably, this method proceeds through a unique mechanism (Figure 18) involving five steps: i) anion exchange between the iridium catalyst and nickel catalyst; ii) generation of a bromine radical and nickel(I) species in the photocatalytic cycle; iii) hydrogen atom abstraction events between the bromine
Graphical Abstract
Scheme 1: Nickel-catalyzed cross-coupling versus C‒H activation.
Figure 1: Oxidative and reductive quenching cycles of a photocatalyst. [PC] = photocatalyst, A = acceptor, D ...
Scheme 2: Photoredox nickel-catalyzed C(sp3)–H arylation of dimethylaniline (1a).
Scheme 3: Photoredox nickel-catalyzed arylation of α-amino, α-oxy and benzylic C(sp3)‒H bonds with aryl bromi...
Figure 2: Proposed catalytic cycle for the photoredox-mediated HAT and nickel catalysis enabled C(sp3)‒H aryl...
Scheme 4: Photoredox arylation of α-amino C(sp3)‒H bonds with aryl iodides.
Figure 3: Proposed mechanism for photoredox nickel-catalyzed α-amino C‒H arylation with aryl iodides.
Scheme 5: Nickel-catalyzed α-oxy C(sp3)−H arylation of cyclic and acyclic ethers.
Figure 4: Proposed catalytic cycle for the C(sp3)−H arylation of cyclic and acyclic ethers.
Scheme 6: Photochemical nickel-catalyzed C–H arylation of ethers.
Figure 5: Proposed catalytic cycle for the nickel-catalyzed arylation of ethers with aryl bromides.
Scheme 7: Nickel-catalyzed α-amino C(sp3)‒H arylation with aryl tosylates.
Scheme 8: Arylation of α-amino C(sp3)‒H bonds by in situ generated aryl tosylates from phenols.
Scheme 9: Formylation of aryl chlorides through redox-neutral 2-functionalization of 1,3-dioxolane (13).
Scheme 10: Photochemical C(sp3)–H arylation via a dual polyoxometalate HAT and nickel catalytic manifold.
Figure 6: Proposed mechanism for C(sp3)–H arylation through dual polyoxometalate HAT and nickel catalytic man...
Scheme 11: Photochemical nickel-catalyzed α-hydroxy C‒H arylation.
Scheme 12: Photochemical synthesis of fluoxetine (21).
Scheme 13: Photochemical nickel-catalyzed allylic C(sp3)‒H arylation with aryl bromides.
Figure 7: Proposed mechanism for the photochemical nickel-catalyzed allylic C(sp3)‒H arylation with aryl brom...
Scheme 14: Photochemical C(sp3)‒H arylation by the synergy of ketone HAT catalysis and nickel catalysis.
Figure 8: Proposed mechanism for photochemical C(sp3)‒H arylation by the synergy of ketone HAT catalysis and ...
Scheme 15: Benzophenone- and nickel-catalyzed photoredox benzylic C–H arylation.
Scheme 16: Benzaldehyde- and nickel-catalyzed photoredox C(sp3)–H arylation.
Scheme 17: Photoredox and nickel-catalyzed enantioselective benzylic C–H arylation.
Figure 9: Proposed mechanism for the photoredox and nickel-catalyzed enantioselective benzylic C–H arylation.
Scheme 18: Photoredox nickel-catalyzed α-(sp3)‒H arylation of secondary benzamides with aryl bromides.
Scheme 19: Enantioselective sp3 α-arylation of benzamides.
Scheme 20: Nickel-catalyzed decarboxylative vinylation/C‒H arylation of cyclic oxalates.
Figure 10: Proposed mechanism for the nickel-catalyzed decarboxylative vinylation/C‒H arylation of cyclic oxal...
Scheme 21: C(sp3)−H arylation of bioactive molecules using mpg-CN photocatalysis and nickel catalysis.
Figure 11: Proposed mechanism for the mpg-CN/nickel photocatalytic C(sp3)–H arylation.
Scheme 22: Nickel-catalyzed synthesis of 1,1-diarylalkanes from alkyl bromides and aryl bromides.
Figure 12: Proposed mechanism for photoredox nickel-catalyzed C(sp3)–H alkylation via polarity-matched HAT.
Scheme 23: Photoredox nickel-catalyzed C(sp3)‒H alkylation via polarity-matched HAT.
Scheme 24: Benzaldehyde- and nickel-catalyzed photoredox C(sp3)‒H alkylation of ethers.
Scheme 25: Benzaldehyde- and nickel-catalyzed photoredox C(sp3)‒H alkylation of amides and thioethers.
Scheme 26: Photoredox and nickel-catalyzed C(sp3)‒H alkylation of benzamides with alkyl bromides.
Scheme 27: CzIPN and nickel-catalyzed C(sp3)‒H alkylation of ethers with alkyl bromides.
Figure 13: Proposed mechanism for the CzIPN and nickel-catalyzed C(sp3)‒H alkylation of ethers.
Scheme 28: Nickel/photoredox-catalyzed methylation of (hetero)aryl chlorides and acid chlorides using trimethy...
Figure 14: Proposed catalytic cycle for the nickel/photoredox-catalyzed methylation of (hetero)aryl chlorides ...
Scheme 29: Photochemical nickel-catalyzed C(sp3)–H methylations.
Scheme 30: Photoredox nickel catalysis-enabled alkylation of unactivated C(sp3)–H bonds with alkyl bromides.
Scheme 31: Photochemical C(sp3)–H alkenylation with alkenyl tosylates.
Scheme 32: Photoredox nickel-catalyzed hydroalkylation of internal alkynes.
Figure 15: Proposed mechanism for the photoredox nickel-catalyzed hydroalkylation of internal alkynes.
Scheme 33: Photoredox nickel-catalyzed hydroalkylation of activated alkynes with C(sp3)−H bonds.
Scheme 34: Allylation of unactivated C(sp3)−H bonds with allylic chlorides.
Scheme 35: Photochemical nickel-catalyzed α-amino C(sp3)–H allylation of secondary amides with trifluoromethyl...
Scheme 36: Photoredox δ C(sp3)‒H allylation of secondary amides with trifluoromethylated alkenes.
Scheme 37: Photoredox nickel-catalyzed acylation of α-amino C(sp3)‒H bonds of N-arylamines.
Figure 16: Proposed mechanism for the photoredox nickel-catalyzed acylation of α-amino C(sp3)–H bonds of N-ary...
Scheme 38: Photocatalytic α‑acylation of ethers with acid chlorides.
Figure 17: Proposed mechanism for the photocatalytic α‑acylation of ethers with acid chlorides.
Scheme 39: Photoredox and nickel-catalyzed C(sp3)‒H esterification with chloroformates.
Scheme 40: Photoredox nickel-catalyzed dehydrogenative coupling of benzylic and aldehydic C–H bonds.
Figure 18: Proposed reaction pathway for the photoredox nickel-catalyzed dehydrogenative coupling of benzylic ...
Scheme 41: Photoredox nickel-catalyzed enantioselective acylation of α-amino C(sp3)–H bonds with carboxylic ac...
Scheme 42: Nickel-catalyzed C(sp3)‒H acylation with N-acylsuccinimides.
Figure 19: Proposed mechanism for the nickel-catalyzed C(sp3)–H acylation with N-acylsuccinimides.
Scheme 43: Nickel-catalyzed benzylic C–H functionalization with acid chlorides 45.
Scheme 44: Photoredox nickel-catalyzed benzylic C–H acylation with N-acylsuccinimides 84.
Scheme 45: Photoredox nickel-catalyzed acylation of indoles 86 with α-oxoacids 87.
Scheme 46: Nickel-catalyzed aldehyde C–H functionalization.
Figure 20: Proposed catalytic cycle for the photoredox nickel-catalyzed aldehyde C–H functionalization.
Scheme 47: Photoredox carboxylation of methylbenzenes with CO2.
Figure 21: Proposed mechanism for the photoredox carboxylation of methylbenzenes with CO2.
Scheme 48: Decatungstate photo-HAT and nickel catalysis enabled alkene difunctionalization.
Figure 22: Proposed catalytic cycle for the decatungstate photo-HAT and nickel catalysis enabled alkene difunc...
Scheme 49: Diaryl ketone HAT catalysis and nickel catalysis enabled dicarbofunctionalization of alkenes.
Figure 23: Proposed catalytic mechanism for the diaryl ketone HAT catalysis and nickel catalysis enabled dicar...
Scheme 50: Overview of photoredox nickel-catalyzed C–H functionalizations.
Chemical syntheses and salient features of azulene-containing homo- and copolymers
- Vijayendra S. Shetti
Beilstein J. Org. Chem. 2021, 17, 2164–2185, doi:10.3762/bjoc.17.139
- polymerization of azulene (1) by iodine or bromine to obtain polyazulene–iodine/bromine complexes (PAz-I2/PAz-Br2) (Scheme 1). The PAZ-I2 complex was found to be insoluble whereas PAZ-Br2 was sparingly soluble in most of the organic solvents. Although no structure was proposed for these polymer complexes, based
- . The author hopes that this review might stimulate such research efforts in the future. Chemical structure, numbering scheme, and resonance form of azulene. Iminium zwitterionic resonance forms of poly[2(6)-aminoazulene] 31. Synthesis of polyazulene-iodine (PAz-I2) and polyazulene-bromine (PAz-Br2
Graphical Abstract
Figure 1: Chemical structure, numbering scheme, and resonance form of azulene.
Scheme 1: Synthesis of polyazulene-iodine (PAz-I2) and polyazulene-bromine (PAz-Br2) complexes.
Scheme 2: Synthesis of ‘true polyazulene’ 3 or 3’ by cationic polymerization.
Scheme 3: Synthesis of 1,3-polyazulene 5 by Yamamoto protocol.
Scheme 4: Synthesis of 4,7-dibromo-6-(n-alkyl)azulenes 12–14.
Scheme 5: Synthesis of (A) 4,7-diethynyl-6-(n-dodecyl)azulene (16) and (B) 4,7-polyazulene 17 containing an e...
Scheme 6: Synthesis of directly connected 4,7-polyazulenes 18–20.
Scheme 7: Synthesis of (A) tert-butyl N-(6-bromoazulen-2-yl)carbamate (27), (B) dimeric aminoazulene 29, and ...
Figure 2: Iminium zwitterionic resonance forms of poly[2(6)-aminoazulene] 31.
Scheme 8: Synthesis of poly{1,3-bis[2-(3-alkylthienyl)]azulene} 33–38.
Scheme 9: Synthesis of polymer ruthenium complexes 40–43.
Scheme 10: Synthesis of 4,7-polyazulenes 45 containing a thienyl linker.
Scheme 11: Synthesis of azulene-bithiophene 48 and azulene-benzothiadiazole 52 copolymers. Conditions: (a): (i...
Scheme 12: Synthesis of azulene-benzodithiophene copolymer 54 and azulene-bithiophene copolymer 56.
Scheme 13: Synthesis of (A) 5,5’-bis(trimethylstannyl)-3,3’-didodecyl-2,2’-bithiophene (60) and (B) azulene-bi...
Scheme 14: Synthesis of 1,3-bisborylated azulene 67.
Scheme 15: Synthesis of D–A-type azulene-DPP copolymers 69, 71, and 72. Conditions: (a) Pd(PPh3)4, K2CO3, Aliq...
Scheme 16: Synthesis of the key precursor TBAzDI 79.
Scheme 17: Synthesis of TBAzDI-based polymers 81 and 83. Conditions: (a) P(o-tol)3, Pd2(dba)3, PivOH, Cs2CO3, ...
Scheme 18: Synthesis of (A) 1,3-dibromo-2-arylazulene 92–98 and (B) 2-arylazulene-thiophene copolymers 99–101.
Scheme 19: Synthesis of (A) poly[2,7-(9,9-dialkylfluorenyl)-alt-(1’,3’-azulenyl)] 106–109, (B) 1,3-bis(7-bromo...
Scheme 20: Synthesis of azulene-fluorene copolymers 117–121 containing varying ratios of 1,3- and 4,7-connecte...
Scheme 21: Synthesis of (A) 2,6-dibromoazulene (125), (B) azulene-fluorene copolymer 126, and (C) azulene-fluo...
Scheme 22: Synthesis of 2-arylazulene-fluorene copolymers 131–134.
Scheme 23: Synthesis of azulene-fluorene-benzothiadiazole terpolymers 136–138.
Scheme 24: Synthesis of azulene-carbazole-benzothiadiazole-conjugated polymers 140–144.
Scheme 25: Synthesis of (A) azulene-2-yl methacrylate (146) and (B) the triazole-containing azulene methacryla...
Scheme 26: Synthesis of (A) azulene methacrylate polymer 151 and (B) triazole-containing azulene methacrylate ...
Scheme 27: Synthesis of azulene methyl methacrylate polymers 154, 155 (A and B) and azulene-sulfobetaine metha...
