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Search for "coupling reaction" in Full Text gives 530 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Synthesis of aryl 2-bromo-2-chloro-1,1-difluoroethyl ethers through the base-mediated reaction between phenols and halothane
- Yukiko Karuo,
- Ayaka Kametani,
- Atsushi Tarui,
- Kazuyuki Sato,
- Kentaro Kawai and
- Masaaki Omote
Beilstein J. Org. Chem. 2021, 17, 89–96, doi:10.3762/bjoc.17.9
- , without byproduct formation from a Michael reaction (Table 2, entry 14). When o-aminophenol (1p) was used as the substrate, the coupling reaction occurred on the hydroxy group exclusively to give 2p (Table 2, entry 15). To show the synthetic advantages of the obtained gem-difluoro ethers 2, we examined
Graphical Abstract
Figure 1: Medical compounds having a difluoromethyl group.
Scheme 1: Methods for the synthesis of ethers containing fluorine substituents.
Scheme 2: The previous work reported by Yagupol’skii et al.
Scheme 3: Intramolecular 1,4-addition of 2o.
Scheme 4: Proposed reaction mechanism.
Progress in the total synthesis of inthomycins
- Bidyut Kumar Senapati
Beilstein J. Org. Chem. 2021, 17, 58–82, doi:10.3762/bjoc.17.7
- step due to its high instability. Finally, the Stille cross-coupling reaction between vinylstannane 24 and dienyl iodide (rac)-20 using PdCl2(CN)2 and triethylamine in DMF produced racemic inthomycin A (or phthoxazolin A) (rac)-1 in 22% yield (Scheme 1). Although the overall yield of this route was
- very low, this work certainly established the basis for the future enantioselective syntheses of inthomycins and related natural products. In 2002, Moloney et al. described an efficient synthetic route using the Stille coupling reaction as the key step to accomplish the synthesis of phenyl analogues of
- Scheme 6, compound 70) [21]. Next, the key Stille coupling reaction of dienylstannane (E,E)-(–)-69 with oxazole vinyl iodide 48 using Pd(PPh3)4/CsF/CuI conditions [51][52] gave ester (+)-11 in 85% yield. The ester (+)-11 was then hydrolyzed with lithium hydroxide to give the corresponding acid (+)-73 in
Graphical Abstract
Figure 1: The inthomycins A–C (1–3) and structurally closely related compounds.
Figure 2: Syntheses of inthomycins A–C (1–3).
Scheme 1: The first total synthesis of racemic inthomycin A (rac)-1 by Whiting.
Scheme 2: Moloney’s synthesis of the phenyl analogue of inthomycin C ((rac)-3).
Scheme 3: Moloney’s synthesis of phenyl analogues of inthomycins A (rac-1) and B (rac-2).
Scheme 4: The first total synthesis of inthomycin B (+)-2 by R. J. K. Taylor.
Scheme 5: R. J. K. Taylor’s total synthesis of racemic inthomycin A (rac)-1.
Scheme 6: The first total synthesis of inthomycin C ((+)-3) by R. J. K. Taylor.
Scheme 7: The first total synthesis of naturally occurring inthomycin C ((–)-3) by Ryu et al.
Scheme 8: Preparation of E,E-iododiene (+)-84 and Z,E- iododiene 85a.
Scheme 9: Hatakeyama’s total synthesis of inthomycin A (+)-1 and inthomycin B (+)-2.
Scheme 10: Hatakeyama’s total synthesis of inthomycin C ((–)-3).
Scheme 11: Maulide’s formal synthesis of racemic inthomycin C ((rac)-3).
Scheme 12: Hale’s synthesis of dienylstannane (+)-69 and enyne (+)-82b intermediates.
Scheme 13: Hale’s total synthesis of inthomycin C ((+)-3).
Scheme 14: Hale and Hatakeyama’s resynthesis of (3R)-inthomycin C (−)-3 Mosher esters.
Scheme 15: Reddy’s formal syntheses of inthomycin C (+)-3 and inthomycin C ((−)-3).
Scheme 16: Synthesis of the cross-metathesis precursors (rac)-118 and 121.
Scheme 17: Donohoe’s total synthesis of inthomycin C ((−)-3).
Scheme 18: Synthesis of dienylboronic ester (E,E)-128.
Scheme 19: Synthesis of the alkenyl iodides (Z)- and (E)-130.
Scheme 20: Burton’s total synthesis of inthomycin B ((+)-2).
Scheme 21: Burton’s total synthesis of inthomycin C ((−)-3).
Scheme 22: Burton’s total synthesis of inthomycin A ((+)-1).
Scheme 23: Synthesis of common intermediate (Z)-(+)-143a.
Scheme 24: Synthesis of (Z)-and (E)-selective fragments (+)-145a–c.
Scheme 25: Kim’s total synthesis of inthomycins A (+)-1 and B (+)-2.
Scheme 26: Completion of total synthesis of inthomycin C ((–)-3) by Kim.
Circularly polarized luminescent systems fabricated by Tröger's base derivatives through two different strategies
- Cheng Qian,
- Yuan Chen,
- Qian Zhao,
- Ming Cheng,
- Chen Lin,
- Juli Jiang and
- Leyong Wang
Beilstein J. Org. Chem. 2021, 17, 52–57, doi:10.3762/bjoc.17.6
- ]. Then, by Suzuki coupling reaction between 2,8-dibromo-6H,12H-5,11-methanodibenzo[b,f][1,5]diazocine and 4-vinylpyridine, rac-TBPP was successfully obtained in 51.8% yield. Detailed experiments and characterization were described in Supporting Information File 1 (Figures S1–S3). Firstly, rac-TBPP was
Graphical Abstract
Scheme 1: Cartoon representative for rac-TBPP-based CPL-active systems fabricated through two strategies.
Figure 1: Ground-state and excited-state chirality of R2N-TBPP and S2N-TBPP. (a) CD spectra of R2N-TBPP and S...
Figure 2: (a) Fluorescence spectra of rac-TBPP in solution (dash line) and in the rac-TBPP/DGG co-gels. (b) C...
Figure 3: (a) UV–vis absorption spectra of rac-TBPP and rac-TBPP/DGG co-gel (rac-TBPP/DGG = 1:80). (b) FTIR s...
An atom-economical addition of methyl azaarenes with aromatic aldehydes via benzylic C(sp3)–H bond functionalization under solvent- and catalyst-free conditions
- Divya Rohini Yennamaneni,
- Vasu Amrutham,
- Krishna Sai Gajula,
- Rammurthy Banothu,
- Murali Boosa and
- Narender Nama
Beilstein J. Org. Chem. 2020, 16, 3093–3103, doi:10.3762/bjoc.16.259
- -dimethylpyridine (1a) and 1 mmol p-nitrobenzaldehyde (2a) at 135 °C for 24 h in a sealed vial without any catalysts or additive under solvent-free conditions. Thereupon, these optimized conditions were utilized to validate the substrate scope of this direct C–C coupling reaction. A variety of aldehydes, 2a–r, was
Graphical Abstract
Scheme 1: Benzylic addition of aldehydes to azaarenes using different catalysts.
Scheme 2: Synthesis of azaarene derivatives from different precursors.
Scheme 3: Our work: catalyst- and solvent-free benzylic addition of aldehydes to azaarenes.
Scheme 4: Large-scale experiments for the synthesis of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (...
Scheme 5: Plausible mechanism for the formation of 2-(6-methylpyridin-2-yl)-1-(4-nitrophenyl)ethan-1-ol (3a) ...
Deoxyfluorination of acyl fluorides to trifluoromethyl compounds by FLUOLEAD®/Olah’s reagent under solvent-free conditions
- Yumeng Liang,
- Akihito Taya,
- Zhengyu Zhao,
- Norimichi Saito and
- Norio Shibata
Beilstein J. Org. Chem. 2020, 16, 3052–3058, doi:10.3762/bjoc.16.254
- fluorides. Acyl fluorides, which are one type of acyl halides, show distinct stability in the presence of moisture, indicating their suitable reactivity only in selected conditions [19]. In addition to our direct cross-coupling reaction method, several useful synthetic methods for the formation of acyl
- developed various efficient methodologies for the electrophilic [14][15], nucleophilic [16], and radical [17] trifluoromethylation reactions for more than a decade. In recent years, we also reported the direct introduction of an acyl fluoride unit into aromatic compounds by the Pd-catalyzed cross-coupling
- reaction of aryl, vinyl, and heteroaryl iodides with 2-(difluoromethoxy)-5-nitropyridine [18]. A wide variety of acyl fluorides were efficiently obtained in high yields. We were fascinated by the synthetic versatility of acyl fluorides [19] to form other functional groups during our research on acyl
Graphical Abstract
Figure 1: Ratios of CF3-containing drugs in marketed fluoro-pharmaceuticals and registered fluoro-agrochemica...
Figure 2: Selected examples of CF3-containing biologically active molecules.
Scheme 1: Transformation of acyl fluorides to trifluoromethyl compounds. a) Deoxyfluorination of acyl fluorid...
Scheme 2: The substrate scope of acyl fluorides. Reaction conditions: 1 (0.3 mmol), FLUOLEAD® (0.9 mmol, 3.0 ...
Scheme 3: Mechanism of deoxyfluorination of acyl fluorides 1 with FLUOLEAD®/Olah’s reagent to trifluoromethyl...
Naphthalonitriles featuring efficient emission in solution and in the solid state
- Sidharth Thulaseedharan Nair Sailaja,
- Iván Maisuls,
- Jutta Kösters,
- Alexander Hepp,
- Andreas Faust,
- Jens Voskuhl and
- Cristian A. Strassert
Beilstein J. Org. Chem. 2020, 16, 2960–2970, doi:10.3762/bjoc.16.246
- –Miyaura coupling reaction starting from 6,7-dibromo-2,3-dicyanonaphthalene, which was prepared according to the literature [45] (Scheme 2). The compounds with the substituents R = H [46] and t-Bu [47] are already known and were herein investigated for comparative purpose. The standard reaction conditions
Graphical Abstract
Scheme 1: A) Structures of the six investigated 2,3-disubstituted-6,7-diphenylnaphthalene derivatives with va...
Scheme 2: Synthesis of p-phenyl-6,7-disubstituted naphthalene-2,3-dicarbonitrile.
Figure 1: Molecular structure in the crystal of Me as obtained by X-ray diffractometric analysis. Thermal dis...
Figure 2: A) Intermolecular CH…π interactions for compound Me. B) Weak intermolecular π–π stacking interactio...
Figure 3: Normalized absorption spectra of the evaluated compounds in fluid THF at rt. All solutions were opt...
Figure 4: Normalized emission spectra of the evaluated compounds in fluid THF at rt (left) and in a frozen gl...
Figure 5: A) Photographs of H at different THF/H2O ratios under UV excitation (λ = 365 nm). B) Photoluminesce...
A novel and robust heterogeneous Cu catalyst using modified lignosulfonate as support for the synthesis of nitrogen-containing heterocycles
- Bingbing Lai,
- Meng Ye,
- Ping Liu,
- Minghao Li,
- Rongxian Bai and
- Yanlong Gu
Beilstein J. Org. Chem. 2020, 16, 2888–2902, doi:10.3762/bjoc.16.238
- preparing a heterogeneous Cu-based catalyst, the thereby obtained catalyst displayed remarkable performance in the Glaser hetero-coupling reaction. Combining two successful attempts, a further study concerning improvement of the robustness of catalysts and active sites when using LS as support is urgently
Graphical Abstract
Figure 1: Schematic illustration for the preparation of the catalyst in this work.
Figure 2: FTIR spectra of LS, LS-FAS, and LS-FAS-Cu.
Figure 3: Thermogravimetric weight loss of the obtained materials LS-FAS and LS-FAS-Cu.
Figure 4: FSEM imagine of LS-FAS-Cu in different scale label a) 1 μm, b) 200 nm; FTEM images of LS-FAS-Cu in ...
Figure 5: XPS spectra of LS-FAS-Cu in the regions of C 1s, O 1s, Cu 2p3/2 and Cu LMM (inset).
Scheme 1: Substrate scope of LS-FAS-Cu catalyzed three-component reactions of 4-aminoindoles, alkynes and ald...
Figure 6: Recyclability of LS-FAS-Cu, LS-FM-Cu and Resin-Cu in the reaction between compounds 1a, 2a and 3a.
Changed reactivity of secondary hydroxy groups in C8-modified adenosine – lessons learned from silylation
- Jennifer Frommer and
- Sabine Müller
Beilstein J. Org. Chem. 2020, 16, 2854–2861, doi:10.3762/bjoc.16.234
- phosphoramidite building block 9 (Scheme 2). Results and Discussion Typically, the synthesis of C8-alkynyl derivatives relies on C8-bromoadenosine as reactant for the Sonogashira cross-coupling reaction to introduce the amino linker N-(propyn-2-yl)-6-(trifluoroacetamido)hexanamide (L) bearing an alkynyl moiety
Graphical Abstract
Scheme 1: Synthesis of a C8-linker-modified adenosine derivative. (a) 4 equiv TBDMS-Cl, 5 equiv imidazole, DM...
Figure 1: Characterization and assignment of the TBDMS isomers via HSQC (red) and HMBC (blue) NMR measurement...
Scheme 2: New synthetic route to the C8-linker modified adenosine building block. (a) i) 1.2 equiv di-tert-bu...
Enzyme-instructed morphological transition of the supramolecular assemblies of branched peptides
- Dongsik Yang,
- Hongjian He and
- Bing Xu
Beilstein J. Org. Chem. 2020, 16, 2709–2718, doi:10.3762/bjoc.16.221
- synthesis (SPPS) [47] to produce the peptides shown in Scheme 1. We first synthesized the peptide segments (i.e., Fmoc-DEDDDLLIG (1a) and acetyl-DEDDDLLIG (2a)). We kept the tert-butyl protecting groups of aspartic acid for the coupling reaction with Nap-ffky. We used 2,2,2-trifluoroethanol (TFE) in
Graphical Abstract
Figure 1: A) The molecular structures of the branched peptides Nap-ffk(NH2-DEDDDLLIG)y (1) and Nap-ffk(AcNH-D...
Scheme 1: Synthetic route to the branched peptides. (i) HBTU, DIPEA, DMF, 12 h, rt, (ii) TFA, 2 h, rt, and (i...
Figure 2: A) LC–MS spectrum of the proteolytic products after 1 (5 mM) was incubated with proteinase K (5 U/m...
Figure 3: Optical images of solutions of 1 and 2 (5 mM), respectively, with or without proteinase K (5 U/mL) ...
Figure 4: TEM images of the branched peptides before and after the addition of proteinase K into the solution...
Figure 5: Cell viability of HeLa and Saos-2 cells treated with 1 (A) and 2 (B).
Figure 6: Confocal images of HeLa cells treated with a mixture of RPE (8 μg/mL) and A) 1 (400 μM) or B) 2 (40...
Optical detection of di- and triphosphate anions with mixed monolayer-protected gold nanoparticles containing zinc(II)–dipicolylamine complexes
- Lena Reinke,
- Julia Bartl,
- Marcus Koch and
- Stefan Kubik
Beilstein J. Org. Chem. 2020, 16, 2687–2700, doi:10.3762/bjoc.16.219
- obtained in a similar fashion by using (R)-lipoic acid in the coupling reaction. The ligand 2 contained a peripheral 2,2'-dipicolylamine residue for zinc(II) coordination. This group was separated from the lipoic acid anchor group by a C12 chain to ensure that it had a sufficient distance from the
Graphical Abstract
Figure 1: Schematic illustration of the analyte-induced crosslinking of gold nanoparticles containing a mixtu...
Scheme 1: Syntheses of the ligands rac-1 and (R)-1. Conditions: i) TsCl, NaOH, THF, 0 °C, 60 min → 25 °C, 80 ...
Scheme 2: Synthesis of ligand 2. Conditions: i) potassium phthalimide, DMF, 25 °C, 18 h, 67%; ii) 2,2'-dipico...
Figure 2: Photographs of solutions of NPrac-1 in water (0.25 mg/mL) containing different sodium salts at a co...
Figure 3: Sections of the 1H NMR spectra of solutions of NP25 in D2O/CD3OD 1:2 (v/v) between 8.9 and 3.9 ppm ...
Figure 4: Images of vials containing solutions of NP10-Zn (0.25 mg/mL) in water/methanol 1:2 (v/v) and additi...
Figure 5: Photograph of the solutions of the competition experiment. Vial (a) only contained NP10-Zn (and the...
Figure 6: UV–vis spectra of NP10-Zn (0.25 mg/mL in the initial measurement) in water/methanol 1:2 (v/v) conta...
Figure 7: TEM images of NP10-Zn (0.25 mg/mL) in water/methanol 1:2 (v/v) before (a) and after the addition of...
Synthesis and characterization of S,N-heterotetracenes
- Astrid Vogt,
- Florian Henne,
- Christoph Wetzel,
- Elena Mena-Osteritz and
- Peter Bäuerle
Beilstein J. Org. Chem. 2020, 16, 2636–2644, doi:10.3762/bjoc.16.214
- , gave the corresponding β-brominated thienothiophene 4 in 91% yield [6]. Compound 4 was selectively brominated in α-position by using NBS in DMF at room temperature to give dibrominated thienothiophene 5 in 92% yield which was coupled in a Negishi-type cross-coupling reaction with zincated 2,3
- the azide route. The synthesis started from the above mentioned brominated thieno[3,2-b]thiophene 3, which was coupled with zincated 2,3-dibromothiophene 6 in a Negishi-type cross-coupling reaction with Pd(dppf)Cl2 as catalyst to give thiophene-substituted thienothiophene 10 in 72% yield. In the next
Graphical Abstract
Figure 1: Heteroacenes: tetrathienoacene (TTA), S,N-heteroacenes SN4, SN4', and SN4''.
Scheme 1: Synthesis of fused S,N-heterotetracene SN4 9 starting from thieno[3,2-b]thiophene (1).
Scheme 2: Synthesis of parent H-SN4 13 via the azide route.
Scheme 3: Synthesis of tetracyclic H-SN4 13 via the Cadogan route.
Scheme 4: Synthesis of tetracyclic indole derivative 19 via the Cadogan route.
Scheme 5: Synthesis of hexacyclic heteroacene SN4' 22 via the Cadogan route.
Scheme 6: Synthesis of heterotetracene SN4'' 33 via the azide and Buchwald–Hartwig amination route.
Figure 2: UV–vis absorption spectra of TTA, Hex-SN4 9, Pr-SN4'' 33 and fluorescence spectrum of 33 in THF at ...
Figure 3: Energy diagram of the frontier molecular orbitals of heterotetracenes TTA, 9, 13, 19, 22, and 33, a...
Palladium nanoparticles supported on chitin-based nanomaterials as heterogeneous catalysts for the Heck coupling reaction
- Tony Jin,
- Malickah Hicks,
- Davis Kurdyla,
- Sabahudin Hrapovic,
- Edmond Lam and
- Audrey Moores
Beilstein J. Org. Chem. 2020, 16, 2477–2483, doi:10.3762/bjoc.16.201
- Mining and Materials Engineering, McGill University, Montreal, Quebec H3A 0E9, Canada 10.3762/bjoc.16.201 Abstract In this report, chitin and chitosan nanocrystals were used as biomass-based supports for Pd nanoparticles (NPs) used as a heterogeneous catalyst for the Heck coupling reaction. By using a
- deposit Pd NPs directly onto both ChNCs and ChsNCs, and the as-made heterogeneous catalysts were tested with the Heck coupling reaction as a model for catalytic activity. Findings The fabrication of ChNC and ChsNCs was conducted using a procedure previously reported by our group (Lam) (see Supporting
- organic solvents (4:1 DMF/H2O) [26]. Conclusion ChNCs and ChsNCs were explored as sustainable supports for immobilizing Pd NPs to fabricate heterogeneous catalysts for the Heck coupling reaction. Through TEM and XPS analysis, metallic Pd NPs were formed and dispersed on the surface of the supports, while
Graphical Abstract
Scheme 1: Pathway for the formation of ChNC and subsequently ChsNCs from bulk chitin.
Figure 1: TEM micrographs of (a) ChNCs and (b) ChsNCs. Both samples were stained and prepared on glow-dischar...
Scheme 2: Catalyst fabrication method for the deposition of Pd NPs onto chitin (PdNP@ChNC) and chitosan (PdNP...
Figure 2: TEM micrographs of (a) PdNP@ChNCs and (b) PdNP@ChsNCs. The samples were placed on glow discharged T...
Figure 3: High-resolution X-ray photoelectron spectroscopy of the Pd 3d region of (a) PdNP@ChNC and (b) PdNP@...
Recent developments in enantioselective photocatalysis
- Callum Prentice,
- James Morrisson,
- Andrew D. Smith and
- Eli Zysman-Colman
Beilstein J. Org. Chem. 2020, 16, 2363–2441, doi:10.3762/bjoc.16.197
Graphical Abstract
Scheme 1: Amine/photoredox-catalysed α-alkylation of aldehydes with alkyl bromides bearing electron-withdrawi...
Scheme 2: Amine/HAT/photoredox-catalysed α-functionalisation of aldehydes using alkenes.
Scheme 3: Amine/cobalt/photoredox-catalysed α-functionalisation of ketones and THIQs.
Scheme 4: Amine/photoredox-catalysed α-functionalisation of aldehydes or ketones with imines. (a) Using keton...
Scheme 5: Bifunctional amine/photoredox-catalysed enantioselective α-functionalisation of aldehydes.
Scheme 6: Bifunctional amine/photoredox-catalysed α-functionalisation of aldehydes using amine catalysts via ...
Scheme 7: Amine/photoredox-catalysed RCA of iminium ion intermediates. (a) Synthesis of quaternary stereocent...
Scheme 8: Bifunctional amine/photoredox-catalysed RCA of enones in a radical chain reaction initiated by an i...
Scheme 9: Bifunctional amine/photoredox-catalysed RCA reactions of iminium ions with different radical precur...
Scheme 10: Bifunctional amine/photoredox-catalysed radical cascade reactions between enones and alkenes with a...
Scheme 11: Amine/photocatalysed photocycloadditions of iminium ion intermediates. (a) External photocatalyst u...
Scheme 12: Amine/photoredox-catalysed addition of acrolein (94) to iminium ions.
Scheme 13: Dual NHC/photoredox-catalysed acylation of THIQs.
Scheme 14: NHC/photocatalysed spirocyclisation via photoisomerisation of an extended Breslow intermediate.
Scheme 15: CPA/photoredox-catalysed aza-pinacol cyclisation.
Scheme 16: CPA/photoredox-catalysed Minisci-type reaction between azaarenes and α-amino radicals.
Scheme 17: CPA/photoredox-catalysed radical additions to azaarenes. (a) α-Amino radical or ketyl radical addit...
Scheme 18: CPA/photoredox-catalysed reduction of azaarene-derived substrates. (a) Reduction of ketones. (b) Ex...
Scheme 19: CPA/photoredox-catalysed radical coupling reactions of α-amino radicals with α-carbonyl radicals. (...
Scheme 20: CPA/photoredox-catalysed Povarov reaction.
Scheme 21: CPA/photoredox-catalysed reactions with imines. (a) Decarboxylative imine generation followed by Po...
Scheme 22: Bifunctional CPA/photocatalysed [2 + 2] photocycloadditions.
Scheme 23: PTC/photocatalysed oxygenation of 1-indanone-derived β-keto esters.
Scheme 24: PTC/photoredox-catalysed perfluoroalkylation of 1-indanone-derived β-keto esters via a radical chai...
Scheme 25: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 26: Bifunctional hydrogen bonding/photocatalysed intramolecular RCA cyclisation of a quinolone.
Scheme 27: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloadditions of quinolon...
Scheme 28: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloaddition reactions. (a) First use of...
Scheme 29: Bifunctional hydrogen bonding/photocatalysed deracemisation of allenes.
Scheme 30: Bifunctional hydrogen bonding/photocatalysed deracemisation reactions. (a) Deracemisation of sulfox...
Scheme 31: Bifunctional hydrogen bonding/photocatalysed intramolecular [2 + 2] photocycloaddition of coumarins....
Scheme 32: Bifunctional hydrogen bonding/photocatalysed [2 + 2] photocycloadditions of quinolones. (a) Intramo...
Scheme 33: Hydrogen bonding/photocatalysed formal arylation of benzofuranones.
Scheme 34: Hydrogen bonding/photoredox-catalysed dehalogenative protonation of α,α-chlorofluoro ketones.
Scheme 35: Hydrogen bonding/photoredox-catalysed reductions. (a) Reduction of 1,2-diketones. (b) Reduction of ...
Scheme 36: Hydrogen bonding/HAT/photocatalysed deracemisation of cyclic ureas.
Scheme 37: Hydrogen bonding/HAT/photoredox-catalysed synthesis of cyclic sulfonamides.
Scheme 38: Hydrogen bonding/photoredox-catalysed reaction between imines and indoles.
Scheme 39: Chiral cation/photoredox-catalysed radical coupling of two α-amino radicals.
Scheme 40: Chiral phosphate/photoredox-catalysed hydroetherfication of alkenols.
Scheme 41: Chiral phosphate/photoredox-catalysed synthesis of pyrroloindolines.
Scheme 42: Chiral anion/photoredox-catalysed radical cation Diels–Alder reaction.
Scheme 43: Lewis acid/photoredox-catalysed cycloadditions of carbonyls. (a) Formal [2 + 2] cycloaddition of en...
Scheme 44: Lewis acid/photoredox-catalysed RCA reaction using a scandium Lewis acid between α-amino radicals a...
Scheme 45: Lewis acid/photoredox-catalysed RCA reaction using a copper Lewis acid between α-amino radicals and...
Scheme 46: Lewis acid/photoredox-catalysed synthesis of 1,2-amino alcohols from aldehydes and nitrones using a...
Scheme 47: Lewis acid/photocatalysed [2 + 2] photocycloadditions of enones and alkenes.
Scheme 48: Meggers’s chiral-at-metal catalysts.
Scheme 49: Lewis acid/photoredox-catalysed α-functionalisation of ketones with alkyl bromides bearing electron...
Scheme 50: Bifunctional Lewis acid/photoredox-catalysed radical coupling reaction using α-chloroketones and α-...
Scheme 51: Lewis acid/photocatalysed RCA of enones. (a) Using aldehydes as acyl radical precursors. (b) Other ...
Scheme 52: Bifunctional Lewis acid/photocatalysis for a photocycloaddition of enones.
Scheme 53: Lewis acid/photoredox-catalysed RCA reactions of enones using DHPs as radical precursors.
Scheme 54: Lewis acid/photoredox-catalysed functionalisation of β-ketoesters. (a) Hydroxylation reaction catal...
Scheme 55: Bifunctional copper-photocatalysed alkylation of imines.
Scheme 56: Copper/photocatalysed alkylation of imines. (a) Bifunctional copper catalysis using α-silyl amines....
Scheme 57: Bifunctional Lewis acid/photocatalysed intramolecular [2 + 2] photocycloaddition.
Scheme 58: Bifunctional Lewis acid/photocatalysed [2 + 2] photocycloadditions (a) Intramolecular cycloaddition...
Scheme 59: Bifunctional Lewis acid/photocatalysed rearrangement of 2,4-dieneones.
Scheme 60: Lewis acid/photocatalysed [2 + 2] cycloadditions of cinnamate esters and styrenes.
Scheme 61: Nickel/photoredox-catalysed arylation of α-amino acids using aryl bromides.
Scheme 62: Nickel/photoredox catalysis. (a) Desymmetrisation of cyclic meso-anhydrides using benzyl trifluorob...
Scheme 63: Nickel/photoredox catalysis for the acyl-carbamoylation of alkenes with aldehydes using TBADT as a ...
Scheme 64: Bifunctional copper/photoredox-catalysed C–N coupling between α-chloro amides and carbazoles or ind...
Scheme 65: Bifunctional copper/photoredox-catalysed difunctionalisation of alkenes with alkynes and alkyl or a...
Scheme 66: Copper/photoredox-catalysed decarboxylative cyanation of benzyl phthalimide esters.
Scheme 67: Copper/photoredox-catalysed cyanation reactions using TMSCN. (a) Propargylic cyanation (b) Ring ope...
Scheme 68: Palladium/photoredox-catalysed allylic alkylation reactions. (a) Using alkyl DHPs as radical precur...
Scheme 69: Manganese/photoredox-catalysed epoxidation of terminal alkenes.
Scheme 70: Chromium/photoredox-catalysed allylation of aldehydes.
Scheme 71: Enzyme/photoredox-catalysed dehalogenation of halolactones.
Scheme 72: Enzyme/photoredox-catalysed dehalogenative cyclisation.
Scheme 73: Enzyme/photoredox-catalysed reduction of cyclic imines.
Scheme 74: Enzyme/photocatalysed enantioselective reduction of electron-deficient alkenes as mixtures of (E)/(Z...
Scheme 75: Enzyme/photoredox catalysis. (a) Deacetoxylation of cyclic ketones. (b) Reduction of heteroaromatic...
Scheme 76: Enzyme/photoredox-catalysed synthesis of indole-3-ones from 2-arylindoles.
Scheme 77: Enzyme/HAT/photoredox catalysis for the DKR of primary amines.
Scheme 78: Bifunctional enzyme/photoredox-catalysed benzylic C–H hydroxylation of trifluoromethylated arenes.
Synthetic approaches to bowl-shaped π-conjugated sumanene and its congeners
- Shakeel Alvi and
- Rashid Ali
Beilstein J. Org. Chem. 2020, 16, 2212–2259, doi:10.3762/bjoc.16.186
- 1,3,5-tris(bromomethyl)benzene (3) using the flash vacuum pyrolysis (FVP) technique as a key transformation (Scheme 1) [30]. As can be seen from an inspection of Scheme 1, they began their journey with the coupling reaction of 3 with 3-butenylmagnesium bromide in the presence of dilithium
- % yield. Next, the methyl substituents were introduced at the position of the carbonyl groups of 23 to generate the methyl-substituted olefin derivative 25 via alkenyl phosphates 24 by means of three-fold cross-coupling reaction with methylmagnesium iodide in THF. Finally, during the tandem ROM–RCM, they
- energy level and hence may be gifted to achieve a large open-circuit voltage. To this context, Amaya et al. has developed a novel bissumanenylidene 47 starting from the parent sumanene (2) first by converting it into the monoketosumanene followed by McMurry coupling reaction (Scheme 9). Although, they
Graphical Abstract
Figure 1: Representation of corannulene (1) and sumanene (2), the subunits of fullerene (C60).
Scheme 1: Mehta’s unsuccessful effort for the synthesis of sumanene scaffold 2.
Scheme 2: First synthesis of sumanene 2 by Sakurai et al. from norbornadiene 10.
Scheme 3: Synthesis of trimethylsumanene 28 from easily accessible norbornadiene (10).
Scheme 4: Generation of anions 29–31 and the preparation of tris(trimethylsilyl)sumanene 32.
Scheme 5: Synthesis of tri- and hexa-substituted sumanene derivatives.
Scheme 6: Synthesis of bowl-shaped π-extended sumanene derivatives 37a–f.
Scheme 7: Synthesis of monooxasumanene 38, trioxosumanene 40 along with imination of them.
Scheme 8: Synthesis of trimethylsumanenetrione 46 and exo-functionalized products 45a,b.
Scheme 9: Synthesis of bisumanenylidene 47 and sumanene dimer 48 from 2.
Scheme 10: The mono-substitution of 2 to generate diverse mono-sumanene derivatives 49a–d.
Scheme 11: Synthesis of sumanene building block 53 useful for further extension.
Scheme 12: Synthesis of hexafluorosumanene derivative 55 by Sakurai and co-workers.
Scheme 13: Preparation of sumanene-based carbene 60 and its reaction with cyclohexane.
Scheme 14: Barton–Kellogg reaction for the synthesis of sterically hindered alkenes.
Scheme 15: Synthesis of hydroxysumanene 68 by employing Baeyer–Villiger oxidation.
Scheme 16: Synthesis of sumanene derivatives having functionality at an internal carbon.
Scheme 17: Mechanism for nucleophilic substitution reaction at the internal carbon.
Scheme 18: Synthesis of diverse monosubstituted sumanene derivatives.
Scheme 19: Synthesis of di- and trisubstituted sumanene derivatives from sumanene (2).
Scheme 20: Preparation of monochlorosumanene 88 and hydrogenation of sumanene (2).
Scheme 21: The dimer 90 and bissumanenyl 92 achieved from halosumannes.
Scheme 22: Pyrenylsumanene 93 involving the Suzuki-coupling as a key transformation.
Scheme 23: Synthesis of various hexaarylsumanene derivatives using the Suzuki-coupling reaction.
Scheme 24: Synthesis of hexasubstituted sumanene derivatives 96 and 97.
Scheme 25: Synthesis of thioalkylsumanenes via an aromatic nucleophilic substitution reaction.
Scheme 26: Synthesis of tris(ethoxycarbonylethenyl)sumanene derivative 108.
Scheme 27: Synthesis of ferrocenyl-based sumanene derivatives.
Scheme 28: Synthesis of sumanenylferrocene architectures 118 and 119 via Negishi coupling.
Scheme 29: Diosmylation and the synthesis of phenylboronate ester 121 of sumanene.
Scheme 30: Synthesis of the iron-complex of sumanene.
Scheme 31: Synthesis of tri- and mononuclear sumanenyl zirconocene complexes.
Scheme 32: Synthesis of [CpRu(η6-sumanene)]PF6.
Scheme 33: Preparation of sumanene-based porous coordination networks 127 (spherical tetramer units) and 128 (...
Scheme 34: Synthesis of sumanenylhafnocene complexes 129 and 130.
Scheme 35: Synthesis of 134 and 135 along with PdII coordination complex 136.
Scheme 36: Synthesis of alkali metals sumanene complex K7(C21H102−)2(C21H93−)·8THF (137) containing di- and tr...
Scheme 37: The encapsulation of a Cs+ ion between two sumanenyl anions.
Scheme 38: Synthesis of monothiasumanene 140 and dithiasumanene 141 from 139.
Scheme 39: Synthesis of trithiasumanene 151 by Otsubo and his co-workers.
Scheme 40: Synthesis of trithiasumanene derivatives 155 and 156.
Scheme 41: Synthetic route towards hexathiolated trithiasumanenes 158.
Scheme 42: Synthesis of triselenasumanene 160 by Shao and teammates.
Scheme 43: Synthesis of tritellurasumanene derivatives from triphenylene skeletons.
Scheme 44: Synthesis of pyrazine-fused sumanene architectures through condensation reaction.
Scheme 45: Treatment of the trichalcogenasumanenes with diverse oxidative reagents.
Scheme 46: Ring-opening reaction with H2O2 and oxone of heterasumanenes 178 and 179.
Scheme 47: Synthesis of polycyclic compounds from sumanene derivatives.
Scheme 48: Synthesis of diimide-based heterocycles reported by Shao’s and co-workers.
Scheme 49: Synthesis of pristine trichalcogenasumanenes, 151, 205, and 206.
Scheme 50: Synthesis of trichalcogenasumanenes via hexaiodotriphenylene precursor 208.
Scheme 51: Synthesis of trisilasumanenes 214 and 215.
Scheme 52: Synthesis of trisilasumanene derivatives 218 and 219.
Scheme 53: Synthesis of novel trigermasumanene derivative 223.
Scheme 54: An attempt towards the synthesis of tristannasumanene derivative 228.
Scheme 55: Synthesis of triphosphasumanene trisulfide 232 from commercially available 229.
Scheme 56: The doping of sumanene derivatives with chalcogens (S, Se, Te) and phosphorus.
Scheme 57: Synthesis of heterasumanene containing three different heteroatoms.
Scheme 58: Synthesis of trichalcogenasumanene derivatives 240 and 179.
Scheme 59: Preparation of trichalcogenasumanenes 245 and 248.
Scheme 60: Design and synthesis of trichalcogenasumanene derivatives 252 and 178.
Scheme 61: Synthesis of spirosumanenes 264–269 and non-spiroheterasumanenes 258–263.
Scheme 62: Synthesis of sumanene-type hetero polycyclic compounds.
Scheme 63: Synthesis of triazasumanenes 288 and its sulfone congener 287.
Scheme 64: Synthesis of C3-symmetric chiral triaryltriazasumanenes via cross-coupling reaction.
Scheme 65: Synthesis of mononaphthosumanene 293 using Suzuki coupling as a key step.
Scheme 66: Synthesis of di- and trinaphthosumanene derivatives 302–304.
Scheme 67: Synthesis of hemifullerene skeletons by Hirao’s group.
Scheme 68: Design and construction of C70 fragment from a C60 sumanene fragment.
Azo-dimethylaminopyridine-functionalized Ni(II)-porphyrin as a photoswitchable nucleophilic catalyst
- Jannis Ludwig,
- Julian Helberg,
- Hendrik Zipse and
- Rainer Herges
Beilstein J. Org. Chem. 2020, 16, 2119–2126, doi:10.3762/bjoc.16.179
- the Suzuki cross-coupling reaction published for a similar system [30], decomposition products and only 25% yield were obtained. Optimization by lowering the reaction temperature increased the yield to 91% (Scheme 1). Switching properties of porphyrin 1 Preliminary investigations on the photochemical
Graphical Abstract
Figure 1: Basicity and nucleophilicity switching of the 4-(N,N-dimethylamino)pyridine “record player” molecul...
Scheme 1: Synthesis of 4-N,N-dimethylamino record player molecule 1 by Suzuki reaction between Ni-porphyrin p...
Figure 2: Composition of the different states of porphyrin 1 (1 mM) in the PSS at 530 nm and 435 nm, determin...
Figure 3: a) UV–vis cuvette with a solution of porphyrin 1 (13.1 µM in THF) and the corresponding UV–vis spec...
Scheme 2: General scheme of the nitroaldol (Henry) reaction that was used to investigate photoswitchable cata...
Scheme 3: DMAP (2), azopyridine trans-4, record player trans- and cis-1 and Ni-porphyrin 8 were used in kinet...
Figure 4: Conversion of 4-nitrobenzaldehyde (6) in the Henry reaction with nitroethane (5) as a function of t...
Syntheses of spliceostatins and thailanstatins: a review
- William A. Donaldson
Beilstein J. Org. Chem. 2020, 16, 1991–2006, doi:10.3762/bjoc.16.166
- compared to the IC50 values of 1.3, 1.0, and 0.36 nM, respectively, for spliceostatin A (4) against the same cell lines. Fragment union via Pd-catalyzed sp2–sp2 coupling A Negishi coupling reaction [42] was used in the Jacobsen synthesis of FR901464 (1, Scheme 23) [17][18]. The hydrozirconation of 91
Graphical Abstract
Figure 1: Structures of spliceostatins/thailanstatins.
Scheme 1: Synthetic routes to protected (2Z,4S)-4-hydroxy-2-butenoic acid fragments.
Scheme 2: Kitahara synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 3: Koide synthesis of (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 4: Nicolaou synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 5: Jacobsen synthesis of the (all-cis)-2,3,5,6-tetrasubstituted tetrahydropyran.
Scheme 6: Unproductive attempt to generate the (all-cis)-tetrahydropyranone 50.
Scheme 7: Ghosh synthesis of the C-7–C-14 (all-cis)-tetrahydropyran segment.
Scheme 8: Ghosh’s alternative route to the (all-cis)-tetrahydropyranone 50.
Scheme 9: Alternative synthesis of the dihydro-3-pyrone 58.
Scheme 10: Kitahara’s 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 11: Kitahara 1st-generation synthesis of the C-1–C-6 fragment of FR901464 (1).
Scheme 12: Nimura/Arisawa synthesis of the C-1-phenyl segment.
Scheme 13: Ghosh synthesis of the C-1–C-6 fragment of FR901464 (1) from (R)-glyceraldehyde acetonide.
Scheme 14: Jacobsen synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 15: Koide synthesis of the C-1–C-7 segment of FR901464 (1).
Scheme 16: Ghosh synthesis of the C-1–C-5 segment 102 of thailanstatin A (7).
Scheme 17: Nicolaou synthesis of the C-1–C-9 segments of spliceostatin D (9) and thailanstatins A (7) and B (5...
Scheme 18: Ghosh synthesis of the C-1–C-6 segment 115 of spliceostatin E (10).
Scheme 19: Fragment coupling via Wittig and modified Julia olefinations by Kitahara.
Scheme 20: Fragment coupling via cross-metathesis by Koide.
Scheme 21: The Ghosh synthesis of spliceostatin A (4), FR901464 (1), spliceostatin E (10), and thailanstatin m...
Scheme 22: Arisawa synthesis of a C-1-phenyl analog of FR901464 (1).
Scheme 23: Jacobsen fragment coupling by a Pd-catalyzed Negishi coupling.
Scheme 24: Nicolaou syntheses of thailanstatin A and B (7 and 5) and spliceostatin D (9) via a Pd-catalyzed Su...
Scheme 25: The Ghosh synthesis of spliceostatin G (11) via Suzuki–Miyaura coupling.
Synthesis of 3(2)-phosphonylated thiazolo[3,2-a]oxopyrimidines
- Ksenia I. Kaskevich,
- Anastasia A. Babushkina,
- Vladislav V. Gurzhiy,
- Dmitrij M. Egorov,
- Nataly I. Svintsitskaya and
- Albina V. Dogadina
Beilstein J. Org. Chem. 2020, 16, 1947–1954, doi:10.3762/bjoc.16.161
- thiazolopyrimidine-5-ones by reacting 6-methyl-2-thiouracils with bromoethynylketones has been reported by Shishkin and co-workers (Scheme 4) [20]. The authors for the first time proved the structure of the 5-oxo isomer by single crystal X-ray diffraction analysis. The Pd-catalyzed Sonogashira coupling reaction
- ]thiazol-2-yl)-2-(7-R-5-oxo-5H-thiazolo[3,2-a]pyrimidin-3-yl)acetonitriles. Synthesis of 3-acyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-ones. Sonogashira coupling reaction of 6-amino-2-thiouracil with propargyl bromide. Reactions of 6-substituted 2-thiouracils 1a,b with chloroethynylphosphonates 2a–c
Graphical Abstract
Figure 1: Structure of ritanserin and setoperone drugs.
Scheme 1: One-pot synthesis of 5(7)-oxothiazolopyrimidine-6-carbonitriles.
Scheme 2: Synthesis of thiazolopyrimidine-5-ones through the reaction of 2-aminothiazoles with ethyl acetoace...
Scheme 3: Synthesis of 2-(benzo[d]thiazol-2-yl)-2-(7-R-5-oxo-5H-thiazolo[3,2-a]pyrimidin-3-yl)acetonitriles.
Scheme 4: Synthesis of 3-acyl-7-methyl-5H-thiazolo[3,2-a]pyrimidin-5-ones.
Scheme 5: Sonogashira coupling reaction of 6-amino-2-thiouracil with propargyl bromide.
Scheme 6: Reactions of 6-substituted 2-thiouracils 1a,b with chloroethynylphosphonates 2a–c.
Scheme 7: Reaction of 5-methyl-2-thiouracil (1c) with chloroethynylphosphonates 2a–c.
Scheme 8: Reaction of 2-thiouracil (1d) with chloroethynylphosphonates 2a–c.
Scheme 9: Reaction of 6-trifluoromethyl-2-thiouracil (1e) with chloroethynylphosphonates 2a–c.
Scheme 10: A plausible mechanism of the reaction between 6-trifluoromethyl-2-thiouracil (1e) and chloroethynyl...
Synergy between supported ionic liquid-like phases and immobilized palladium N-heterocyclic carbene–phosphine complexes for the Negishi reaction under flow conditions
- Edgar Peris,
- Raúl Porcar,
- María Macia,
- Jesús Alcázar,
- Eduardo García-Verdugo and
- Santiago V. Luis
Beilstein J. Org. Chem. 2020, 16, 1924–1935, doi:10.3762/bjoc.16.159
- -bromobenzoate (6) to form methyl 4-benzylbenzoate (7) was used to evaluate the activity of the palladium catalysts on polymer support (Scheme 2). The Negishi reaction is a potent cross-coupling reaction in organic chemistry. Notably, it has much value for the synthesis of fine chemicals and medicinal drugs [22
Graphical Abstract
Scheme 1: Synthesis of NHC-supported catalysts.
Scheme 2: Negishi benchmark reaction.
Figure 1: Negishi reaction catalyzed by immobilized NHC–Pd complexes. Conditions: methyl 4-bromobenzoate (0.2...
Scheme 3: Synthesis of immobilized NHC–Pd–RuPhos.
Figure 2: Negishi model reaction between 5 and 6 under flow conditions catalyzed by 4b. V = 0.535 mL, 363 mg ...
Figure 3: Negishi model reaction under flow conditions catalyzed by 8a. V = 2.9 mL, 1.25 g of catalyst, resid...
Figure 4: Negishi reaction between 5 and 6 catalyzed by 8a in the presence of SILLPs. a) Yield (%) vs time fo...
Figure 5: TEM images of the polymers after the Negishi reaction between 5 and 6. a) 8a, bar scale 20 nm, PdNP...
Scheme 4: Pd species immobilized onto SILLPs. i) 1 g SILLP 10, 100 mg PdCl2 in milli-Q® water (100 mL 1% HCl,...
Figure 6: Negishi reaction between 5 and 6 catalyzed by 11. 1 equiv methyl 4-bromobenzoate (6, 0.25 mmol), 2 ...
Figure 7: Negishi reaction between 5 and 6 under flow conditions catalyzed by 8a in the presence of a scaveng...
Figure 8: Effect of the structure of the SILLP scavenger for the Negishi reaction between 5 and 6 under flow ...
Figure 9: TEM images of the polymer after the Negishi reaction between 5 and 6 under flow conditions. a) 8a + ...
One-pot and metal-free synthesis of 3-arylated-4-nitrophenols via polyfunctionalized cyclohexanones from β-nitrostyrenes
- Haruyasu Asahara,
- Minami Hiraishi and
- Nagatoshi Nishiwaki
Beilstein J. Org. Chem. 2020, 16, 1830–1836, doi:10.3762/bjoc.16.150
- group hinder the electrophilic modification at the 3-position. Generally, the aryl group is introduced by a Suzuki–Miyaura cross-coupling reaction [4][5], for which 3-bromo-4-nitrophenol must be prepared by the nitration of 3-bromophenol [6][7]. An alternative approach is the nitration of 3-arylphenol
Graphical Abstract
Scheme 1: Synthetic scheme of the 3-arylated-4-nitrophenols 5.
Figure 1: X-ray crystallography of the major isomer of 4a. The thermal ellipsoids indicate 50% probability.
Scheme 2: Conversion from 3a to 4a and one-pot synthesis of 4a.
Scheme 3: Deuteration of cyclohexanone 4a.
Scheme 4: A plausible mechanism for the formation of 5a.
Figure 2: Resonance structure of nitroalkenes 1b and 1d.
Heterogeneous photocatalysis in flow chemical reactors
- Christopher G. Thomson,
- Ai-Lan Lee and
- Filipe Vilela
Beilstein J. Org. Chem. 2020, 16, 1495–1549, doi:10.3762/bjoc.16.125
Graphical Abstract
Figure 1: A) Bar chart of the publications per year for the topics “Photocatalysis” (49,662 instances) and “P...
Figure 2: A) Professor Giacomo Ciamician and Dr. Paolo Silber on their roof laboratory at the University of B...
Scheme 1: PRC trifluoromethylation of N-methylpyrrole (1) using hazardous gaseous CF3I safely in a flow react...
Figure 3: A) Unit cells of the three most common crystal structures of TiO2: rutile, brookite, and anatase. R...
Figure 4: Illustration of the key semiconductor photocatalysis events: 1) A photon with a frequency exceeding...
Figure 5: Photocatalytic splitting of water by oxygen vacancies on a TiO2(110) surface. Reprinted with permis...
Figure 6: Proposed adsorption modes of A) benzene, B) chlorobenzene, C) toluene, D) phenol, E) anisole, and F...
Figure 7: Structures of the sulfonate-containing organic dyes RB5 (3) and MX-5B (4) and the adsorption isothe...
Figure 8: Idealised triclinic unit cell of a g-C3N4 type polymer, displaying possible hopping transport scena...
Figure 9: Idealised structure of a perfect g-C3N4 sheet. The central unit highlighted in red represents one t...
Figure 10: Timeline of the key processes of charge transport following the photoexcitation of g-C3N4, leading ...
Scheme 2: Photocatalytic bifunctionalisation of heteroarenes using mpg-C3N4, with the selected examples 5 and ...
Figure 11: A) Structure of four linear conjugated polymer photocatalysts for hydrogen evolution, displaying th...
Figure 12: Graphical representation of the common methods used to immobilise molecular photocatalysts (PC) ont...
Figure 13: Wireless light emitter-supported TiO2 (TiO2@WLE) HPCat spheres powered by resonant inductive coupli...
Figure 14: Graphical representation of zinc–perylene diimide (Zn-PDI) supramolecular assembly photocatalysis v...
Scheme 3: Upconversion of NIR photons to the UV frequency by NaYF4:Yb,Tm nanocrystals sequentially coated wit...
Figure 15: Types of reactors employed in heterogeneous photocatalysis in flow. A) Fixed bed reactors and the s...
Figure 16: Electrochemical potential of common semiconductor, transition metal, and organic dye-based photocat...
Scheme 4: Possible mechanisms of an immobilised molecular photoredox catalyst by oxidative or reductive quenc...
Scheme 5: Scheme of the CMB-C3N4 photocatalytic decarboxylative fluorination of aryloxyacetic acids, with the...
Scheme 6: Scheme of the g-C3N4 photocatalytic desilylative coupling reaction in flow and proposed mechanism [208].
Scheme 7: Proposed mechanism of the radical cyclisation of unsaturated alkyl 2-bromo-1,3-dicarbonyl compounds...
Scheme 8: N-alkylation of benzylamine and schematic of the TiO2-coated microfluidic device [213].
Scheme 9: Proposed mechanism of the Pt@TiO2 photocatalytic deaminitive cyclisation of ʟ-lysine (23) to ʟ-pipe...
Scheme 10: A) Proposed mechanism for the photocatalytic oxidation of phenylboronic acid (24). B) Photos and SE...
Scheme 11: Proposed mechanism for the DA-CMP3 photocatalytic aza-Henry reaction performed in a continuous flow...
Scheme 12: Proposed mechanism for the formation of the cyclic product 32 by TiO2-NC HPCats in a slurry flow re...
Scheme 13: Reaction scheme for the photocatalytic synthesis of homo and hetero disulfides in flow and scope of...
Scheme 14: Reaction scheme for the MoOx/TiO2 HPCat oxidation of cyclohexane (34) to benzene. The graph shows t...
Scheme 15: Proposed mechanism of the TiO2 HPC heteroarene C–H functionalisation via aryl radicals generated fr...
Scheme 16: Scheme of the oxidative coupling of benzylamines with the HOTT-HATN HPCat and selected examples of ...
Scheme 17: Photocatalysis oxidation of benzyl alcohol (40) to benzaldehyde (41) in a microflow reactor coated ...
Figure 17: Mechanisms of Dexter and Forster energy transfer.
Scheme 18: Continuous flow process for the isomerisation of alkenes with an ionic liquid-immobilised photocata...
Scheme 19: Singlet oxygen synthetic step in the total synthesis of canataxpropellane [265].
Scheme 20: Scheme and proposed mechanism of the singlet oxygen photosensitisation by CMP_X HPCats, with the st...
Scheme 21: Structures of CMP HPCat materials applied by Vilela and co-workers for the singlet oxygen photosens...
Scheme 22: Polyvinylchloride resin-supported TDCPP photosensitisers applied for singlet oxygen photosensitisat...
Scheme 23: Structure of the ionically immobilised TPP photosensitiser on amberlyst-15 ion exchange resins (TPP...
Scheme 24: Photosensitised singlet oxygen oxidation of citronellol (46) in scCO2, with automatic phase separat...
Scheme 25: Schematic of PS-Est-BDP-Cl2 being applied for singlet oxygen photosensitisation in flow. A) Pseudo-...
Scheme 26: Reaction scheme of the singlet oxygen oxidation of furoic acid (54) using a 3D-printed microfluidic...
Figure 18: A) Photocatalytic bactericidal mechanism by ROS oxidative cleavage of membrane lipids (R = H, amino...
Figure 19: A) Suggested mechanisms for the aqueous pollutant degradation by TiO2 in a slurry flow reactor [284-287]. B)...
Figure 20: Schematic of the flow system used for the degradation of aqueous oxytetracycline (56) solutions [215]. M...
Scheme 27: Degradation of a salicylic acid (57) solution by a coupled solar photoelectro-Fenton (SPEF) process...
Figure 21: A) Schematic flow diagram using the TiO2-coated NETmix microfluidic device for an efficient mass tr...
Recent synthesis of thietanes
- Jiaxi Xu
Beilstein J. Org. Chem. 2020, 16, 1357–1410, doi:10.3762/bjoc.16.116
Graphical Abstract
Figure 1: Examples of biologically active thietane-containing molecules.
Figure 2: The diverse methods for the synthesis of thietanes.
Scheme 1: Synthesis of 1-(thietan-2-yl)ethan-1-ol (10) from 3,5-dichloropentan-2-ol (9).
Scheme 2: Synthesis of thietanose nucleosides 2,14 from 2,2-bis(bromomethyl)propane-1,3-diol (11).
Scheme 3: Synthesis of methyl 3-vinylthietane-3-carboxylate (19).
Scheme 4: Synthesis of 1,6-thiazaspiro[3.3]heptane (24).
Scheme 5: Synthesis of 6-amino-2-thiaspiro[3.3]heptane hydrochloride (28).
Scheme 6: Synthesis of optically active thietane 31 from vitamin C.
Scheme 7: Synthesis of an optically active thietane nucleoside from diethyl L-tartrate (32).
Scheme 8: Synthesis of thietane-containing spironucleoside 40 from 5-aldo-3-O-benzyl-1,2-O-isopropylidene-α-D...
Scheme 9: Synthesis of optically active 2-methylthietane-containing spironucleoside 43.
Scheme 10: Synthesis of a double-linked thietane-containing spironucleoside 48.
Scheme 11: Synthesis of two diastereomeric thietanose nucleosides via 2,4-di(benzyloxymethyl)thietane (49).
Scheme 12: Synthesis of the thietane-containing PI3k inhibitor candidate 54.
Scheme 13: Synthesis of the spirothietane 57 as the key intermediate to Nuphar sesquiterpene thioalkaloids.
Scheme 14: Synthesis of spirothietane 61 through a direct cyclic thioetherification of 3-mercaptopropan-1-ol.
Scheme 15: Synthesis of thietanes 66 from 1,3-diols 62.
Scheme 16: Synthesis of thietanylbenzimidazolone 75 from (iodomethyl)thiazolobenzimidazole 70.
Scheme 17: Synthesis of 2-oxa-6-thiaspiro[3.3]heptane (80) from bis(chloromethyl)oxetane 76 and thiourea.
Scheme 18: Synthesis of the thietane-containing glycoside, 2-O-p-toluenesulfonyl-4,6-thioanhydro-α-D-gulopyran...
Scheme 19: Synthesis of methyl 4,6-thioanhydro-α-D-glucopyranoside (89).
Scheme 20: Synthesis of thietane-fused α-D-galactopyranoside 93.
Scheme 21: Synthesis of thietane-fused α-D-gulopyranoside 100.
Scheme 22: Synthesis of 3,5-anhydro-3-thiopentofuranosides 104.
Scheme 23: Synthesis of anhydro-thiohexofuranosides 110, 112 and 113 from from 1,2:4,5-di-O-isopropylidene D-f...
Scheme 24: Synthesis of optically active thietanose nucleosides from D- and L-xyloses.
Scheme 25: Synthesis of thietane-fused nucleosides.
Scheme 26: Synthesis of 3,5-anhydro-3-thiopentofuranosides.
Scheme 27: Synthesis of 2-amino-3,5-anhydro-3-thiofuranoside 141.
Scheme 28: Synthesis of thietane-3-ols 145 from (1-chloromethyl)oxiranes 142 and hydrogen sulfide.
Scheme 29: Synthesis of thietane-3-ol 145a from chloromethyloxirane (142a).
Scheme 30: Synthesis of thietane-3-ols 145 from 2-(1-haloalkyl)oxiranes 142 and 147 with ammonium monothiocarb...
Scheme 31: Synthesis of 7-deoxy-5(20)thiapaclitaxel 154a, a thietane derivative of taxoids.
Scheme 32: Synthesis of 5(20)-thiadocetaxel 158 from 10-deacetylbaccatin III (155).
Scheme 33: Synthesis of thietane derivatives 162 as precursors for deoxythiataxoid synthesis through oxiraneme...
Scheme 34: Synthesis of 7-deoxy 5(20)-thiadocetaxel 154b.
Scheme 35: Mechanism for the formation of the thietane ring in 171 from oxiranes with vicinal leaving groups 1...
Scheme 36: Synthesis of cis-2,3-disubstituted thietane 175 from thiirane-2-methanol 172.
Scheme 37: Synthesis of a bridged thietane 183 from aziridine cyclohexyl tosylate 179 and ammonium tetrathiomo...
Scheme 38: Synthesis of thietanes via the photochemical [2 + 2] cycloaddition of thiobenzophenone 184a with va...
Scheme 39: Synthesis of spirothietanes through the photo [2 + 2] cycloaddition of cyclic thiocarbonyls with ol...
Scheme 40: Photochemical synthesis of spirothietane-thioxanthenes 210 from thioxanthenethione (208) and butatr...
Scheme 41: Synthesis of thietanes 213 from 2,4,6-tri(tert-butyl)thiobenzaldehyde (211) with substituted allene...
Scheme 42: Photochemical synthesis of spirothietanes 216 and 217 from N-methylthiophthalimide (214) with olefi...
Scheme 43: Synthesis of fused thietanes from quadricyclane with thiocarbonyl derivatives 219.
Scheme 44: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-methyldithiosuccinimides ...
Scheme 45: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-methylthiosuccinimide/thi...
Scheme 46: Synthesis of tricyclic thietanes via the photo [2 + 2] cycloaddition of N-alkylmonothiophthalimides...
Scheme 47: Synthesis of spirothietanes from dithiosuccinimides 223 with 2,3-dimethyl-2-butene (215a).
Scheme 48: Synthesis of thietanes 248a,b from diaryl thione 184b and ketene acetals 247a,b.
Scheme 49: Photocycloadditions of acridine-9-thiones 249 and pyridine-4(1H)-thione (250) with 2-methylacrynitr...
Scheme 50: Synthesis of thietanes via the photo [2 + 2] cycloaddition of mono-, di-, and trithiobarbiturates 2...
Scheme 51: Synthesis of spirothietanes via the photo [2 + 2] cycloaddition of 1,1,3-trimethyl-2-thioxo-1,2-dih...
Scheme 52: Synthesis of spirothietanes via the photo [2 + 2] cycloaddition of thiocoumarin 286 with olefins.
Scheme 53: Photochemical synthesis of thietanes 296–299 from semicyclic and acyclic thioimides 292–295 and 2,3...
Scheme 54: Photochemical synthesis of spirothietane 301 from 1,3,3-trimethylindoline-2-thione (300) and isobut...
Scheme 55: Synthesis of spirobenzoxazolethietanes 303 via the photo [2 + 2] cycloaddition of alkyl and aryl 2-...
Scheme 56: Synthesis of spirothietanes from tetrahydrothioxoisoquinolines 306 and 307 with olefins.
Scheme 57: Synthesis of spirothietanes from 1,3-dihydroisobenzofuran-1-thiones 311 and benzothiophene-1-thione...
Scheme 58: Synthesis of 2-triphenylsilylthietanes from phenyl triphenylsilyl thioketone (316) with electron-po...
Scheme 59: Diastereoselective synthesis of spiropyrrolidinonethietanes 320 via the photo [2 + 2] cycloaddition...
Scheme 60: Synthesis of bicyclic thietane 323 via the photo [2 + 2] cycloaddition of 2,4-dioxo-3,4-dihydropyri...
Scheme 61: Photo-induced synthesis of fused thietane-2-thiones 325 and 326 from silacyclopentadiene 324 and ca...
Scheme 62: Synthesis of highly strained tricyclic thietanes 328 via the intramolecular photo [2 + 2] cycloaddi...
Scheme 63: Synthesis of tri- and pentacyclic thietanes 330 and 332, respectively, through the intramolecular p...
Scheme 64: Synthesis of tricyclic thietanes 334 via the intramolecular photo [2 + 2] cycloaddition of N-vinylt...
Scheme 65: Synthesis of tricyclic thietanes 336 via the intramolecular photo [2 + 2] cycloaddition of N-but-3-...
Scheme 66: Synthesis of tricyclic thietanes via the intramolecular photo [2 + 2] cycloaddition of N-but-3-enyl...
Scheme 67: Synthesis of tetracyclic thietane 344 through the intramolecular photo [2 + 2] cycloaddition of N-[...
Scheme 68: Synthesis of tri- and tetracyclic thietanes 348, 350, and 351, through the intramolecular photo [2 ...
Scheme 69: Synthesis of tetracyclic fused thietane 354 via the photo [2 + 2] cycloaddition of vinyl 2-thioxo-3H...
Scheme 70: Synthesis of highly rigid thietane-fused β-lactams via the intramolecular photo [2 + 2] cycloadditi...
Scheme 71: Asymmetric synthesis of a highly rigid thietane-fused β-lactam 356a via the intramolecular photo [2...
Scheme 72: Diastereoselective synthesis of the thietane-fused β-lactams via the intramolecular photo [2 + 2] c...
Scheme 73: Asymmetric synthesis of thietane-fused β-lactams 356 via the intramolecular photo [2 + 2] cycloaddi...
Scheme 74: Synthesis of the bridged bis(trifluoromethyl)thietane from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-di...
Scheme 75: Synthesis of the bridged-difluorothietane 368 from 2,2,4,4-tetrafluoro-1,3-dithietane (367) and qua...
Scheme 76: Synthesis of bis(trifluoromethyl)thietanes from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietane (3...
Scheme 77: Synthesis of 2,2-dimethylthio-4,4-di(trifluoromethyl)thietane (378) from 2,2,4,4-tetrakis(trifluoro...
Scheme 78: Formation of bis(trifluoromethyl)thioacetone (381) through nucleophilic attack of dithietane 363 by...
Scheme 79: Synthesis of 2,2-bis(trifluoromethyl)thietanes from 2,2,4,4-tetrakis(trifluoromethyl)-1,3-dithietan...
Scheme 80: Synthesis of the bridged bis(trifluoromethyl)thietane 364 from of 2,2,4,4-tetrakis(trifluoromethyl)...
Scheme 81: Synthesis of 2,4-diiminothietanes 390 from alkenimines and 4-methylbenzenesulfonyl isothiocyanate (...
Scheme 82: Synthesis of arylidene 2,4-diiminothietanes 393 starting from phosphonium ylides 391 and isothiocya...
Scheme 83: Synthesis of thietane-2-ylideneacetates 397 through a DABCO-catalyzed formal [2 + 2] cycloaddition ...
Scheme 84: Synthesis of 3-substituted thietanes 400 from (1-chloroalkyl)thiiranes 398.
Scheme 85: Synthesis of N-(thietane-3-yl)azaheterocycles 403 and 404 through reaction of chloromethylthiirane (...
Scheme 86: Synthesis of 3-sulfonamidothietanes 406 from sulfonamides and chloromethylthiirane (398a).
Scheme 87: Synthesis of N-(thietane-3-yl)isatins 408 from chloromethylthiirane (398a) and isatins 407.
Scheme 88: Synthesis of 3-(nitrophenyloxy)thietanes 410 from nitrophenols 409 and chloromethylthiirane (398a).
Scheme 89: Synthesis of N-aryl-N-(thietane-3-yl)cyanamides 412 from N-arylcyanamides 411 and chloromethylthiir...
Scheme 90: Synthesis of 1-(thietane-3-yl)pyrimidin-2,4(1H,3H)-diones 414 from chloromethylthiirane (398a) and ...
Scheme 91: Synthesis of 2,4-diiminothietanes 418 from 2-iminothiiranes 416 and isocyanoalkanes 415.
Scheme 92: Synthesis of 2-vinylthietanes 421 from thiiranes 419 and 3-chloroallyl lithium (420).
Scheme 93: Synthesis of thietanes from thiiranes 419 and trimethyloxosulfonium iodide 424.
Scheme 94: Mechanism for synthesis of thietanes 425 from thiiranes 419 and trimethyloxosulfonium iodide 424.
Scheme 95: Synthesis of functionalized thietanes from thiiranes and dimethylsulfonium acylmethylides.
Scheme 96: Mechanism for the rhodium-catalyzed synthesis of functionalized thietanes 429 from thiiranes 419 an...
Scheme 97: Synthesis of 3-iminothietanes 440 through thermal isomerization from 4,5-dihydro-1,3-oxazole-4-spir...
Scheme 98: Synthesis of thietanes 443 from 3-chloro-2-methylthiolane (441) through ring contraction.
Scheme 99: Synthesis of an optically active thietanose 447 from D-xylose involving a ring contraction.
Scheme 100: Synthesis of optically thietane 447 via the DAST-mediated ring contraction of 448.
Scheme 101: Synthesis of the optically thietane nucleoside 451 via the ring contraction of thiopentose in 450.
Scheme 102: Synthesis of spirothietane 456 from 3,3,5,5-tetramethylthiolane-2,4-dithione (452) and benzyne (453...
Scheme 103: Synthesis of thietanes 461 via photoisomerization of 2H,6H-thiin-3-ones 459.
Scheme 104: Phosphorodithioate-mediated synthesis of 1,4-diarylthietanes 465.
Scheme 105: Mechanism of the phosphorodithioate-mediated synthesis of 1,4-diarylthietanes 465.
Scheme 106: Phosphorodithioate-mediated synthesis of trisubstituted thietanes (±)-470.
Scheme 107: Mechanism on the phosphorodithioate-mediated synthesis of trisubstituted thietanes.
Scheme 108: Phosphorodithioate-mediated synthesis of thietanes (±)-475.
Scheme 109: Phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes from aldehydes 476 and acrylon...
Scheme 110: Phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes via a one-pot three-component ...
Scheme 111: Mechanism for the phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes via three-co...
Scheme 112: Phosphorodithioate-mediated synthesis of substituted 3-nitrothietanes.
Scheme 113: Mechanism on the phosphorodithioate-mediated synthesis of 1,2-disubstituted thietanes (±)-486.
Scheme 114: Asymmetric synthesis of (S)-2-phenylthietane (497).
Scheme 115: Asymmetric synthesis of optically active 2,4-diarylthietanes.
Scheme 116: Synthesis of 3-acetamidothietan-2-one 503 via the intramolecular thioesterification of 3-mercaptoal...
Scheme 117: Synthesis of 4-substituted thietan-2-one via the intramolecular thioesterification of 3-mercaptoalk...
Scheme 118: Synthesis of 4,4-disubstituted thietan-2-one 511 via the intramolecular thioesterification of the 3...
Scheme 119: Synthesis of a spirothietan-2-one 514 via the intramolecular thioesterification of 3-mercaptoalkano...
Scheme 120: Synthesis of thiatetrahydrolipstatin starting from (S)-(−)-epichlorohydrin ((S)-142a).
Scheme 121: Synthesis of 2-phenethyl-4-(propan-2-ylidene)thietane (520) from 5-bromo-6-methyl-1-phenylhept-5-en...
Scheme 122: Synthesis of 2-phenethyl-4-(propan-2-ylidene)thietane (520) directly from S-(5-bromo-6-methyl-1-phe...
Scheme 123: Synthesis of 2-alkylidenethietanes from S-(2-bromoalk-1-en-4-yl)thioacetates.
Scheme 124: Synthesis of 2-alkylidenethietanes from S-(2-bromo/chloroalk-1-en-4-yl)thiols.
Scheme 125: Synthesis of spirothietan-3-ol 548 from enone 545 and ammonium hydrosulfide.
Scheme 126: Asymmetric synthesis of the optically active thietanoside from cis-but-2-ene-1,4-diol (47).
Scheme 127: Synthesis of 2-alkylidenethietan-3-ols 557 via the fluoride-mediated cyclization of thioacylsilanes ...
Scheme 128: Synthesis of 2-iminothietanes via the reaction of propargylbenzene (558) and isothiocyanates 560 in...
Scheme 129: Synthesis of 2-benzylidenethietane 567 via the nickel complex-catalyzed electroreductive cyclizatio...
Scheme 130: Synthesis of 2-iminothietanes 569 via the photo-assisted electrocyclic reaction of N-monosubstitute...
Scheme 131: Synthesis of ethyl 3,4-diiminothietane-2-carboxylates from ethyl thioglycolate (570) and bis(imidoy...
Scheme 132: Synthesis of N-(thietan-3-yl)-α-oxoazaheterocycles from azaheterocyclethiones and chloromethyloxira...
Scheme 133: Synthesis of thietan-3-yl benzoate (590) via the nickel-catalyzed intramolecular reductive thiolati...
Scheme 134: Synthesis of 2,2-bis(trifluoromethyl)thietane from 3,3-bis(trifluoromethyl)-1,2-dithiolane.
Scheme 135: Synthesis of thietanes from enamines and sulfonyl chlorides.
Scheme 136: Synthesis of spirothietane 603 via the [2 + 3] cycloaddition of 2,2,4,4-tetramethylcyclobutane-1,3-...
Scheme 137: Synthesis of thietane (605) from 1-bromo-3-chloropropane and sulfur.
Highly selective Diels–Alder and Heck arylation reactions in a divergent synthesis of isoindolo- and pyrrolo-fused polycyclic indoles from 2-formylpyrrole
- Carlos H. Escalante,
- Eder I. Martínez-Mora,
- Carlos Espinoza-Hicks,
- Alejandro A. Camacho-Dávila,
- Fernando R. Ramos-Morales,
- Francisco Delgado and
- Joaquín Tamariz
Beilstein J. Org. Chem. 2020, 16, 1320–1334, doi:10.3762/bjoc.16.113
- with the complexity of its structures [11][19][20][21][22][23][24][25][26][27]. The intramolecular Heck arylation coupling reaction is among the most useful strategies for the construction of these compounds (Scheme 1) [11][21]. For example, isoindolo[2,1-a]indoles 6 have been prepared by the
- -polycyclic structures [42], we herein combined both approaches shown in Scheme 1 to design the construction of pentacycles 11, after carrying out an uncommon but highly diastereoselective Diels–Alder cycloaddition followed by a coupling reaction. This route also allowed out the aromatization of the B ring to
- intramolecular Heck cross-coupling reaction of the octahydroindoles 9/10 to the pentacycles 11, the process was explored with the simple substrates 8c,d and 8g (Scheme 4). Thus, the Pd(0)-catalyzed cyclization of the latter vinylpyrroles with potassium acetate and using acetonitrile or dimethylacetamide (DMA) as
Graphical Abstract
Figure 1: Fused aza-hetero polycyclic frames and natural pyrrolizine- and isoindole-containing alkaloids.
Scheme 1: Synthetic approaches for the preparation of pyrrolo-fused aza-hetero polycyclic frames.
Scheme 2: Preparation of 1,2-substituted pyrroles 8a–f and 8i,j.
Scheme 3: Diels–Alder cycloadditions of pyrroles 8a–j and 16a–b with maleimides 7b–c.
Figure 2: Structures of 9m (a) and 10m (b) as determined by single-crystal X-ray diffraction crystallography ...
Scheme 4: Pd(0)-catalyzed intramolecular Heck cross-coupling reaction of 2-vinylpyrroles 8c,d and 8g.
Scheme 5: Synthesis of 2-vinylpyrroles 8k,l and their Pd(0)-catalyzed intramolecular Heck cross-coupling to p...
Scheme 6: Diastereoselective Diels–Alder reaction of pyrrolo[2,1-a]isoindole 18a with 7c.
Scheme 7: Synthetic approach to the fused aza-heterocyclic pentacycle 12.
Figure 3: M06-2X/6-31+G(d,p) Optimized geometry for each of the SCs (a and d), TSs (b and e) and ADs (c and f...
Figure 4: M06-2X/6-31+G(d,p) Optimized geometry for each of the TSs of the Diels–Alder reactions of dienes 8b...
Figure 5: M06-2X/6-31+G(d,p) Optimized geometry of the endo SCs (a) and TSs (b) for the Diels–Alder reaction ...
Oxime radicals: generation, properties and application in organic synthesis
- Igor B. Krylov,
- Stanislav A. Paveliev,
- Alexander S. Budnikov and
- Alexander O. Terent’ev
Beilstein J. Org. Chem. 2020, 16, 1234–1276, doi:10.3762/bjoc.16.107
- (products 46a,b, 46m,n), 1,3-diketones (product 46r), as well as lactones (products 46o–q) were used in the oxidative C–O coupling reaction. The coupling of oximes with 1,3-diketones proceeded in lower yields than with 1,3-ketoesters (products 46a and 46r). Despite the presence of t-BuOOH in the system, a
Graphical Abstract
Figure 1: Imine-N-oxyl radicals (IV) discussed in the present review and other classes of N-oxyl radicals (I–...
Figure 2: The products of decomposition of iminoxyl radicals generated from oximes by oxidation with Ag2O.
Scheme 1: Generation of oxime radicals and study of the kinetics of their decay by photolysis of the solution...
Scheme 2: Synthesis of di-tert-butyliminoxyl radical and its decomposition products.
Scheme 3: The proposed reaction pathway of the decomposition of di-tert-butyliminoxyl radical (experimentally...
Scheme 4: Monomolecular decomposition of the tert-butyl(triethylmethyl)oxime radical.
Scheme 5: The synthesis and stability of the most stable dialkyl oxime radicals – di-tert-butyliminoxyl and d...
Scheme 6: The formation of iminoxyl radicals from β-diketones under the action of NO2.
Scheme 7: Synthesis of the diacetyliminoxyl radical.
Scheme 8: Examples of long-living oxime radicals with electron-withdrawing groups and the conditions for thei...
Figure 3: The electronic structure iminoxyl radicals and their geometry compared to the corresponding oximes.
Figure 4: Bond dissociation enthalpies (kcal/mol) of oximes and N,N-disubstituted hydroxylamines calculated o...
Scheme 9: Examples demonstrating the low reactivity of the di-tert-butyliminoxyl radical towards the substrat...
Scheme 10: The reactions of di-tert-butyliminoxyl radical with unsaturated hydrocarbons involving hydrogen ato...
Scheme 11: Possible mechanisms of reaction of di-tert-butyliminoxyl radical with alkenes.
Scheme 12: Products of the reaction between di-tert-butyliminoxyl radical and phenol derivatives.
Scheme 13: The reaction of di-tert-butyliminoxyl radical with amines.
Scheme 14: Reaction of di-tert-butyliminoxyl radicals with organolithium reagents.
Scheme 15: Cross-dehydrogenative C–O coupling of 1,3-dicarbonyl compounds with oximes under the action of mang...
Scheme 16: Cross-dehydrogenative C–O coupling of 1,3-dicarbonyl compounds with oximes under the action of Cu(BF...
Scheme 17: Oxidative C–O coupling of benzylmalononitrile (47) with 3-(hydroxyimino)pentane-2,4-dione (19).
Scheme 18: The proposed mechanism of the oxidative coupling of benzylmalononitrile (47) with diacetyl oxime (19...
Scheme 19: Oxidative C–O coupling of pyrazolones with oximes under the action of Fe(ClO4)3.
Scheme 20: The reaction of diacetyliminoxyl radical with pyrazolones.
Scheme 21: Oxidative C–O coupling of oximes with acetonitrile, ketones, and esters.
Scheme 22: Intramolecular cyclizations of oxime radicals to form substituted isoxazolines or cyclic nitrones.
Scheme 23: TEMPO-mediated oxidative cyclization of oximes with C–H bond cleavage.
Scheme 24: Proposed reaction mechanism of oxidative cyclization of oximes with C–H bond cleavage.
Scheme 25: Selectfluor/Bu4NI-mediated C–H oxidative cyclization of oximes.
Scheme 26: Oxidative cyclization of N-benzyl amidoximes to 1,2,4-oxadiazoles.
Scheme 27: The formation of quinazolinone 73a from 5-phenyl-4,5-dihydro-1,2,4-oxadiazole 74 under air.
Scheme 28: DDQ-mediated oxidative cyclization of thiohydroximic acids.
Scheme 29: Plausible mechanism of the oxidative cyclization of thiohydroximic acids.
Scheme 30: Silver-mediated oxidative cyclization of α-halogenated ketoximes and 1,3-dicarbonyl compounds.
Scheme 31: Possible pathway of one-pot oxidative cyclization of α-halogenated ketoximes and 1,3-dicarbonyl com...
Scheme 32: T(p-F)PPT-catalyzed oxidative cyclization of oximes with the formation of 1,2,4-oxadiazolines.
Scheme 33: Intramolecular cyclization of iminoxyl radicals involving multiple C=C and N=N bonds.
Scheme 34: Oxidative cyclization of β,γ- and γ,δ-unsaturated oximes employing the DEAD or TEMPO/DEAD system wi...
Scheme 35: Cobalt-catalyzed aerobic oxidative cyclization of β,γ-unsaturated oximes.
Scheme 36: Manganese-catalyzed aerobic oxidative cyclization of β,γ-unsaturated oximes.
Scheme 37: Visible light photocatalytic oxidative cyclization of β,γ-unsaturated oximes.
Scheme 38: TBAI/TBHP-mediated radical cascade cyclization of the β,γ-unsaturated oximes.
Scheme 39: TBAI/TBHP-mediated radical cascade cyclization of vinyl isocyanides with β,γ-unsaturated oximes.
Scheme 40: tert-Butylnitrite-mediated oxidative cyclization of unsaturated oximes with the introduction of an ...
Scheme 41: Transformation of unsaturated oxime to oxyiminomethylisoxazoline via the confirmed dimeric nitroso ...
Scheme 42: tert-Butylnitrite-mediated oxidative cyclization of unsaturated oximes with the introduction of a n...
Scheme 43: Synthesis of cyano-substituted oxazolines from unsaturated oximes using the TBN/[RuCl2(p-cymene)]2 ...
Scheme 44: Synthesis of trifluoromethylthiolated isoxazolines from unsaturated oximes.
Scheme 45: Copper-сatalyzed oxidative cyclization of β,γ-unsaturated oximes with the introduction of an azido ...
Scheme 46: TBHP-mediated oxidative cascade cyclization of β,γ-unsaturated oximes and unsaturated N-arylamides.
Scheme 47: Copper-сatalyzed oxidative cyclization of unsaturated oximes with the introduction of an amino grou...
Scheme 48: TEMPO-mediated oxidative cyclization of unsaturated oximes followed by elimination.
Scheme 49: Oxidative cyclization of β,γ-unsaturated oximes with the introduction of a trifluoromethyl group.
Scheme 50: Oxidative cyclization of unsaturated oximes with the introduction of a nitrile group.
Scheme 51: Oxidative cyclization of β,γ-unsaturated oximes to isoxazolines with the introduction of a nitrile ...
Scheme 52: Oxidative cyclization of β,γ-unsaturated oximes to isoxazolines with the introduction of a sulfonyl...
Scheme 53: Oxidative cyclization of β,γ- and γ,δ-unsaturated oximes to isoxazolines with the introduction of a...
Scheme 54: Oxidative cyclization of β,γ-unsaturated oximes to isoxazolines with the introduction of a thiocyan...
Scheme 55: PhI(OAc)2-mediated oxidative cyclization of oximes with C–S and C–Se bond formation.
Scheme 56: PhI(OAc)2-mediated oxidative cyclization of unsaturated oximes accompanied by alkoxylation.
Scheme 57: PhI(OAc)2-mediated cyclization of unsaturated oximes to methylisoxazolines.
Scheme 58: Oxidative cyclization-alkynylation of unsaturated oximes.
Scheme 59: TEMPO-mediated oxidative cyclization of C-glycoside ketoximes to C-glycosylmethylisoxazoles.
Scheme 60: Silver-сatalyzed oxidative cyclization of β,γ-unsaturated oximes with formation of fluoroalkyl isox...
Scheme 61: Oxidative cyclization of β,γ-unsaturated oximes with the formation of haloalkyl isoxazolines.
Scheme 62: Cyclization of β,γ-unsaturated oximes into haloalkyl isoxazolines under the action of the halogenat...
Scheme 63: Synthesis of haloalkyl isoxazoles and cyclic nitrones via oxidative cyclization and 1,2-halogen shi...
Scheme 64: Electrochemical oxidative cyclization of diaryl oximes.
Scheme 65: Copper-сatalyzed cyclization and dioxygenation oximes containing a triple C≡C bond.
Scheme 66: Photoredox-catalyzed sulfonylation of β,γ-unsaturated oximes by sulfonyl hydrazides.
Scheme 67: Oxidative cyclization of β,γ-unsaturated oximes with introduction of sulfonate group.
Scheme 68: Ultrasound-promoted oxidative cyclization of β,γ-unsaturated oximes.
Copper-based fluorinated reagents for the synthesis of CF2R-containing molecules (R ≠ F)
- Louise Ruyet and
- Tatiana Besset
Beilstein J. Org. Chem. 2020, 16, 1051–1065, doi:10.3762/bjoc.16.92
- 87% yield) was investigated (Scheme 8) [52]. Finally, the Poisson’s group developed a methodology for the Ullman cross-coupling reaction between the in situ-generated CuCF2PO(OEt)2 and aryl iodides containing a coordinating group (e.g., CO2CH3, COCH3, NO2), at the ortho-position of the halide [52
- (0)-mediated reductive cross-coupling reaction between the iodobenzene and various 2-bromo-1,1,2,2-tetrafluoroethyl derivatives (RCF2CF2Br) was developed presumably involving a RCF2CF2Cu species (Scheme 21) [76]. In 2015, Yagupolskii and co-workers investigated the synthesis of perfluoroalkylcopper
Graphical Abstract
Scheme 1: Synthesis of the first isolable (NHC)CuCF2H complexes from TMSCF2H and their application for the sy...
Scheme 2: Pioneer works for the in situ generation of CuCF2H from TMSCF2H and from n-Bu3SnCF2H. Phen = 1,10-p...
Scheme 3: A Sandmeyer-type difluoromethylation reaction via the in situ generation of CuCF2H from TMSCF2H. a ...
Scheme 4: A one pot, two-step sequence for the difluoromethylthiolation of various classes of compounds via t...
Scheme 5: A copper-mediated oxidative difluoromethylation of terminal alkynes via the in situ generation of a...
Scheme 6: A copper-mediated oxidative difluoromethylation of heteroarenes.
Scheme 7: Synthesis of difluoromethylphosphonate-containing molecules using the in situ-generated CuCF2PO(OEt)...
Scheme 8: Synthesis of difluoromethylphosphonate-containing molecules using in situ-generated CuCF2PO(OEt)2 s...
Scheme 9: Synthesis of difluoromethylphosphonate-containing molecules using in situ-generated CuCF2PO(OEt)2 s...
Scheme 10: Synthesis of (diethylphosphono)difluoromethylthiolated molecules using in situ-generated CuCF2PO(OE...
Scheme 11: Access to (diethylphosphono)difluoromethylthiolated molecules via the in situ generation of CuCF2PO...
Scheme 12: Synthesis of (phenylsulfonyl)difluoromethyl-containing molecules via the in situ generation of CuCF2...
Scheme 13: Copper-mediated 1,1-difluoroethylation of diaryliodonium salts by using the in situ-generated CuCF2...
Scheme 14: Pioneer works for the pentafluoroethylation and heptafluoropropylation using a copper-based reagent...
Scheme 15: Pentafluoroethylation of (hetero)aryl bromides using the (Phen)CuCF2CF3 complex. 19F NMR yields wer...
Scheme 16: Synthesis of pentafluoroethyl ketones using the (Ph3P)Cu(phen)CF2CF3 reagent. 19F NMR yields were g...
Scheme 17: Synthesis of (Phen)2Cu(O2CCF2RF) and functionalization of (hetero)aryl iodides.
Scheme 18: Pentafluoroethylation of arylboronic acids and (hetero)aryl bromides via the in situ-generated CuCF2...
Scheme 19: In situ generation of CuCF2CF3 species from a cyclic-protected hexafluoroacetone and KCu(Ot-Bu)2. 19...
Scheme 20: Pentafluoroethylation of bromo- and iodoalkenes. Only examples of isolated compounds were depicted.
Scheme 21: Fluoroalkylation of aryl halides via a RCF2CF2Cu species.
Scheme 22: Synthesis of perfluoroorganolithium copper species or perfluroalkylcopper derivatives from iodoperf...
Scheme 23: Formation of the PhenCuCF2CF3 reagent by means of TFE and pentafluoroethylation of iodoarenes and a...
Scheme 24: Generation of a CuCF2CF3 reagent from TMSCF3 and applications.
Fluorinated phenylalanines: synthesis and pharmaceutical applications
- Laila F. Awad and
- Mohammed Salah Ayoup
Beilstein J. Org. Chem. 2020, 16, 1022–1050, doi:10.3762/bjoc.16.91
- )-iodoalanine 2. The reaction was activated using Pd(0) as a catalyst. A palladium-catalyzed cross-coupling reaction between an organozinc iodide and aryl halides offers a convenient method for the direct preparation of protected fluorinated Phe analogues 3. Thus, cross coupling of the protected iodoalanine 2
- the protected ᴅ,ʟ-N-Boc-2-bromophenylalanine (89) using a Stille coupling reaction to give the o-vinyl derivative 90 as key intermediate. A hydroboration reaction of compound 90 afforded the primary alcohol 91, which was directly fluorinated and deprotected to give the free amino acids 93 (ᴅ and ʟ
Graphical Abstract
Figure 1: Categories I–V of fluorinated phenylalanines.
Scheme 1: Synthesis of fluorinated phenylalanines via Jackson’s method.
Scheme 2: Synthesis of all-cis-tetrafluorocyclohexylphenylalanines.
Scheme 3: Synthesis of ʟ-4-[sulfono(difluoromethyl)]phenylalanine (nPt: neopentyl, TCE: trichloroethyl).
Scheme 4: Synthesis of ʟ-4-[sulfono(difluoromethyl)]phenylalanine derivatives 17.
Scheme 5: Synthesis of fluorinated Phe analogues from Cbz-protected aminomalonates.
Scheme 6: Synthesis of tetrafluorophenylalanine analogues via the 3-methyl-4-imidazolidinone auxiliary 25.
Scheme 7: Synthesis of tetrafluoro-Phe derivatives via chiral auxiliary 31.
Scheme 8: Synthesis of 2,5-difluoro-Phe and 2,4,5-trifluoro-Phe via Schöllkopf reagent 34.
Scheme 9: Synthesis of 2-fluoro- and 2,6-difluoro Fmoc-Phe derivatives starting from chiral auxiliary 39.
Scheme 10: Synthesis of 2-[18F]FPhe via chiral auxiliary 43.
Scheme 11: Synthesis of FPhe 49a via photooxidative cyanation.
Scheme 12: Synthesis of FPhe derivatives via Erlenmeyer azalactone synthesis.
Scheme 13: Synthesis of (R)- and (S)-2,5-difluoro Phe via the azalactone method.
Scheme 14: Synthesis of 3-bromo-4-fluoro-(S)-Phe (65).
Scheme 15: Synthesis of [18F]FPhe via radiofluorination of phenylalanine with [18F]F2 or [18F]AcOF.
Scheme 16: Synthesis of 4-borono-2-[18F]FPhe.
Scheme 17: Synthesis of protected 4-[18F]FPhe via arylstannane derivatives.
Scheme 18: Synthesis of FPhe derivatives via intermediate imine formation.
Scheme 19: Synthesis of FPhe derivatives via Knoevenagel condensation.
Scheme 20: Synthesis of FPhe derivatives 88a,b from aspartic acid derivatives.
Scheme 21: Synthesis of 2-(2-fluoroethyl)phenylalanine derivatives 93 and 95.
Scheme 22: Synthesis of FPhe derivatives via Zn2+ complexes.
Scheme 23: Synthesis of FPhe derivatives via Ni2+ complexes.
Scheme 24: Synthesis of 3,4,5-trifluorophenylalanine hydrochloride (109).
Scheme 25: Synthesis of FPhe derivatives via phenylalanine aminomutase (PAM).
Scheme 26: Synthesis of (R)-2,5-difluorophenylalanine 115.
Scheme 27: Synthesis of β-fluorophenylalanine via 2-amino-1,3-diol derivatives.
Scheme 28: Synthesis of β-fluorophenylalanine derivatives via the oxazolidinone chiral auxiliary 122.
Scheme 29: Synthesis of β-fluorophenylalanine from pyruvate hemiketal 130.
Scheme 30: Synthesis of β-fluorophenylalanine (136) via fluorination of β-hydroxyphenylalanine (137).
Scheme 31: Synthesis of β-fluorophenylalanine from aziridine derivatives.
Scheme 32: Synthesis of β-fluorophenylalanine 136 via direct fluorination of pyruvate esters.
Scheme 33: Synthesis of β-fluorophenylalanine via fluorination of ethyl 3-phenylpyruvate enol using DAST.
Scheme 34: Synthesis of β-fluorophenylalanine derivatives using photosensitizer TCB.
Scheme 35: Synthesis of β-fluorophenylalanine derivatives using Selectflour and dibenzosuberenone.
Scheme 36: Synthesis of protected β-fluorophenylalanine via aziridinium intermediate 150.
Scheme 37: Synthesis of β-fluorophenylalanine derivatives via fluorination of α-hydroxy-β-aminophenylalanine d...
Scheme 38: Synthesis of β-fluorophenylalanine derivatives from α- or β-hydroxy esters 152a and 155.
Scheme 39: Synthesis of a series of β-fluoro-Phe derivatives via Pd-catalyzed direct fluorination of β-methyle...
Scheme 40: Synthesis of series of β-fluorinated Phe derivatives using quinoline-based ligand 162 in the Pd-cat...
Scheme 41: Synthesis of β,β-difluorophenylalanine derivatives from 2,2-difluoroacetaldehyde derivatives 164a,b....
Scheme 42: Synthesis of β,β-difluorophenylalanine derivatives via an imine chiral auxiliary.
Scheme 43: Synthesis of α-fluorophenylalanine derivatives via direct fluorination of protected Phe 174.
Figure 2: Structures of PET radiotracers of 18FPhe derivatives.
Figure 3: Structures of melfufen (179) and melphalan (180) anticancer drugs.
Figure 4: Structure of gastrazole (JB95008, 181), a CCK2 receptor antagonist.
Figure 5: Dual CCK1/CCK2 antagonist 182.
Figure 6: Structure of sitagliptin (183), an antidiabetic drug.
Figure 7: Structure of retaglpitin (184) and antidiabetic drug.
Figure 8: Structure of evogliptin (185), an antidiabetic drug.
Figure 9: Structure of LY2497282 (186) a DPP-4 inhibitor for the treatment of type II diabetes.
Figure 10: Structure of ulimorelin (187).
Figure 11: Structure of GLP1R (188).
Figure 12: Structures of Nav1.7 blockers 189 and 190.
