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Search for "heteroatom" in Full Text gives 241 result(s) in Beilstein Journal of Organic Chemistry. Showing first 200.
Thermally activated delayed fluorescence (TADF) emitters: sensing and boosting spin-flipping by aggregation
- Ashish Kumar Mazumdar,
- Gyana Prakash Nanda,
- Nisha Yadav,
- Upasana Deori,
- Upasha Acharyya,
- Bahadur Sk and
- Pachaiyappan Rajamalli
Beilstein J. Org. Chem. 2022, 18, 1177–1187, doi:10.3762/bjoc.18.122
- in designing heteroatom-containing (N, O, S, etc.) chromophores [26]. The lone-pair electrons of heteroatoms can possess a certain degree of basicity, which results in sensitivity to acid. Consequently, the lone pair may be protonated and deprotonated by consecutively adding acid and base. The
- to the singlet state via RISC [17][27]. Heteroatom lone-pair electrons are sensitive to acid and, once protonated, to base, which would facilitate the tuning of optical properties in such media [21][22]. Herein, (4-(3,6-di-tert-butyl-9H-carbazol-9-yl)phenyl)(pyridin-4-yl)methanone (BPy-pTC) and (4-(9
Graphical Abstract
Scheme 1: Synthetic schemes of BPy-pTC and BPy-p3C.
Figure 1: (a) Normalized absorption spectra of BPy-pTC and BPy-p3C in toluene at room temperature; (b) normal...
Figure 2: Transient photoluminescence decay (λex = 375 nm) of (a) BPy-pTC and (b) BPy-p3C in degassed THF (10...
Figure 3: AIEE studies: Emission spectra (λex = 375 nm, 10 µM) of (a) BPy-pTC and (d) BPy-p3C in THF with inc...
Figure 4: Normalized fluorescence at room temperature and phosphorescence spectra at 77 K (λex = 375 nm, 10 µ...
Figure 5: Transient photoluminescence decay (λex = 375 nm, 20 µM) of (a) BPy-pTC and (b) BPy-p3C aggregates i...
Figure 6: Fluorescence switching by acid and base fumes exposure: Emission spectra (λex = 375 nm) of (a) BPy-p...
Figure 7: Fluorescence intensity vs number of exposures for (a) BPy-p3C and (b) BPy-pTC thin films upon expos...
Heterogeneous metallaphotoredox catalysis in a continuous-flow packed-bed reactor
- Wei-Hsin Hsu,
- Susanne Reischauer,
- Peter H. Seeberger,
- Bartholomäus Pieber and
- Dario Cambié
Beilstein J. Org. Chem. 2022, 18, 1123–1130, doi:10.3762/bjoc.18.115
- light-mediated carbon–heteroatom cross-couplings of sodium sulfinates, carboxylic acids and sulphonamides with aryl halides (Figure 2) [28]. Although recyclable, batch reactions are characterized by long reaction times (24 h). Here, we present a detailed investigation of a continuous-flow strategy for
- micro-batch reactors (SMBR), b) rotor-stator spinning disk reactors, c) slurry with pulsator, d) packed bed. Light-mediated carbon–heteroatom cross-couplings. The yields reported are the NMR yields obtained in flow with the optimized conditions described later. DMAc = dimethylacetamide, DMSO = dimethyl
Graphical Abstract
Figure 1: Different approaches to heterogeneous photochemistry in flow. a) Serial micro-batch reactors (SMBR)...
Figure 2: Light-mediated carbon–heteroatom cross-couplings. The yields reported are the NMR yields obtained i...
Figure 3: Flow diagram of the experimental setup loaded in an injection loop with the reaction mixture.
Figure 4: Flow diagram of the experimental setup adopted and time necessary to obtain steady-state conditions...
Figure 5: The production campaign of 1 for a seven day experiment.
Figure 6: Photo of the packed column with a helical static mixer (polished SS316, 10 cm length, 15 mixing ele...
Scheme 1: C–O coupling between 4-iodobenzotrifluoride and N-(Boc)-proline.
Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds: density functional theory study on product selectivity
- Naoki Kise and
- Toshihiko Sakurai
Beilstein J. Org. Chem. 2022, 18, 956–962, doi:10.3762/bjoc.18.95
- studied using DFT calculations. Keywords: 2-acylbenzoates; chlorotrimethylsilane; 3-(3-cyanoethyl)phthalides; 2-cyanonaphthalen-1-ols; electroductive coupling; Introduction The electroreductive coupling between carbon–heteroatom and carbon–carbon double bonds is one of the promising methods for carbon
Graphical Abstract
Scheme 1: Electroreductive coupling of phthalic anhydrides with α,β-unsaturated carbonyl compounds and subseq...
Scheme 2: Electroreductive coupling of phthalimides with α,β-unsaturated carbonyl compounds and subsequent tr...
Scheme 3: Electroreductive coupling of 2-acylbenzoates with α,β-unsaturated carbonyl compounds and subsequent...
Scheme 4: Electroreductive coupling of 1a with 2a and subsequent transformation to 2-cyanonaphthalene-1-ol (3a...
Scheme 5: Presumed reaction mechanism of electroreductive coupling of 1 with 2a and subsequent transformation...
Scheme 6: Electroreductive coupling of 1a with 2c and subsequent treatment with 1 M HCl.
Post-synthesis from Lewis acid–base interaction: an alternative way to generate light and harvest triplet excitons
- Hengjia Liu and
- Guohua Xie
Beilstein J. Org. Chem. 2022, 18, 825–836, doi:10.3762/bjoc.18.83
- optoelectronic properties of a fluorene-based copolymer with an sp2 nitrogen heteroatom via supramolecular coordination [33]. The PL emission in solution showed an obvious red-shifted profile. The polymer LED with different molar equivalents of Lewis acids was investigated. The EL peak wavelength was gradually
Graphical Abstract
Figure 1: Chemical structures of Lewis acid examples.
Figure 2: Chemical structures of Lewis basic fluorescent polymer poly{2,5-pyridylene-co-1,4-[2,5-bis(2-ethylh...
Figure 3: (a) Normalized PL spectra of films with compound 1 doped with different Lewis acids. (b) PL spectra...
Figure 4: Schematic diagram of a BF3·OEt2 vapor-treated device and the macroscopic gradation emissive pattern...
Figure 5: Chemical structures of Lewis basic fluorescent compounds 3–14.
Figure 6: (a) PL spectra of compound 6 in toluene after addition of 0.0 (black line), 0.1 (red line), 0.3 (gr...
Figure 7: Photos of a solution of compound 12 and B(C6F5)3 at different ratios in toluene under a 365 nm UV l...
Figure 8: Structure of small molecule 15 containing pyridine and thiazole groups reported by Bazan et al. and...
Figure 9: (a) 1H NMR spectra in the aromatic region and (b) 19F NMR spectra of compound 15 (top) and the mixt...
Figure 10: Pyrazine-containing polymers 19 and 20 investigated by Li et al.
Figure 11: (a) HOMO/LUMO orbitals and energy levels (unit: eV) and (b) electrostatic potential surface (EPS) m...
Figure 12: (a) UV–vis absorbance and (b) PL spectra (excited by 330 nm) for 35DCzPPy (compound 14), B(C6F5)3, ...
Figure 13: (a) Schematic diagram of the low-band gap materials 21 and 22. (b) Ground state geometry optimizati...
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
- packing structures of these compounds. Spectroscopic results and our previous work showed that the combination of molecular structure change and heteroatom replacement from S to Se could precisely modulate molecular energy levels. Keywords: crystal structure; double helicene; regioselective synthesis
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).
DDQ in mechanochemical C–N coupling reactions
- Shyamal Kanti Bera,
- Rosalin Bhanja and
- Prasenjit Mal
Beilstein J. Org. Chem. 2022, 18, 639–646, doi:10.3762/bjoc.18.64
- moiety in 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ), it was well established as a hydride transfer reagent in various organic reactions [14][15]. Generally, DDQ assists in dehydrogenation reactions in organic synthesis [16]. In this context, various carbon–heteroatom bond formation reactions such
Graphical Abstract
Figure 1: Our work on mechanochemical C–N coupling reactions using DDQ. The newly formed C–N bonds are shown ...
Figure 2: Scope of the mechanochemical synthesis of substituted benzimidazoles.
Figure 3: Synthesis of quinazolin-4(3H)-one derivatives.
Figure 4: The substrate scope for the synthesis of quinazolin-4(3H)-one derivatives.
Figure 5: a) Control experiment and b) Plausible mechanism.
Figure 6: Large-scale synthesis. a) 1,2-Disubstituted benzimidazoles. b) Substituted quinazolin-4(3H)-ones. R...
Unusual highly diastereoselective Rh(II)-catalyzed dimerization of 3-diazo-2-arylidenesuccinimides provides access to a new dibenzazulene scaffold
- Anastasia Vepreva,
- Alexander S. Bunev,
- Andrey Yu. Kudinov,
- Grigory Kantin,
- Mikhail Krasavin and
- Dmitry Dar’in
Beilstein J. Org. Chem. 2022, 18, 533–538, doi:10.3762/bjoc.18.55
- method for the preparation of this class of compounds [2] and showed that DAS can undergo Rh(II)-catalyzed insertion reactions into the heteroatom–H bonds [3]. In 2020, it was shown that under Rh(II) catalysis, DAS can enter insertion reactions into the C–O bond of ethers [4], a rare transformation for
Graphical Abstract
Figure 1: Previously reported transformations of DAS (1) and their unusual dimerization investigated in this ...
Scheme 1: The result of Rh(II)-catalyzed decomposition of DAS 1r.
Scheme 2: Plausible mechanism for the formation of dimer 2a and indene 3a through the Rh(II)-catalyzed decomp...
Figure 2: Cytotoxicity of N-alkyl-substituted dibenzoazulenodipyrroles 2 against the A549 human lung adenocar...
Amamistatins isolated from Nocardia altamirensis
- Till Steinmetz,
- Wolf Hiller and
- Markus Nett
Beilstein J. Org. Chem. 2022, 18, 360–367, doi:10.3762/bjoc.18.40
- ). Furthermore, the observed chemical shifts indicated that 14 carbons must be sp2-hybridized. Six of them form carbon–heteroatom double bonds (δC 176.9, 176.5, 172.5, 163.9, 163.5, 159.8 ppm) and eight of them are engaged in carbon–carbon double bonds (δC 158.1, 154.4, 133.9, 129.7, 127.5, 120.9, 118.3, 111.7
- shifts. Two of them are engaged in carbon–heteroatom double bonds (δC 170.0, 169.3 ppm) and six of them form carbon–carbon double bonds (δC 163.0, 137.5, 131.5, 120.5. 118.5, 113.0 ppm). This indicates the presence of one ring structure to comply with the required six degrees of unsaturation. With the
Graphical Abstract
Figure 1: Chemical structures of amamistatins (1–5) and a putative biosynthetic shunt product (6) isolated in...
Figure 2: 1H,1H COSY and selected 1H,13C HMBC correlations in compounds 1 and 6.
Figure 3: MS–MS fragmentation of amamistatins (1–5).
Figure 4: Proposed biosynthesis of amamistatins isolated in this study.
Regioselectivity of the SEAr-based cyclizations and SEAr-terminated annulations of 3,5-unsubstituted, 4-substituted indoles
- Jonali Das and
- Sajal Kumar Das
Beilstein J. Org. Chem. 2022, 18, 293–302, doi:10.3762/bjoc.18.33
- constructing carbon–carbon and carbon–heteroatom bonds in organic synthesis [8][9][10]. In the course of their diversity-oriented synthesis of indole-based peri-annulated compounds, You and co-workers in 2013 reported the intramolecular Tsuji–Trost reaction of indolyl allyl carbonates 1 under the catalysis of
- 18 via a concerted protonation and C–C bond formation. Weakened dispersive interactions caused by a substituent or heteroatom resulted in low yields and reduced regioselectivities. In 2020, Li and Van der Eycken and co-workers reported the synthesis of densely functionalized, polycyclic azepino[5,4,3
Graphical Abstract
Scheme 1: SEAr-based, CAr–C bond-forming cyclization or annulation of: (A) substituted arenes/heteroarenes an...
Scheme 2: Indole C3 regioselective intramolecular alkylation of indolyl allyl carbonates.
Scheme 3: Indole C3 regioselective Michael-type cyclization in the total synthesis of (−)-indolactam V.
Scheme 4: Synthesis of azepino[4,3,2-cd]indoles via indole C3 regioselective aza-Michael addition/cyclization...
Scheme 5: Indole C3 regioselective Pictet−Spengler reaction of 2-(1H-indol-4-yl)ethanamines.
Scheme 6: Indole C3 regioselective hydroindolation of cis-β-(α′,α′-dimethyl)-4′-methindolylstyrenes.
Scheme 7: Indole C3 regioselective cyclization leading to the formation of polycyclic azepino[5,4,3-cd]indole...
Scheme 8: Synthesis of azepino[3,4,5-cd]indoles via iridium-catalyzed asymmetric [4 + 3] cycloaddition of rac...
Scheme 9: Aldimine condensation/1,6-hydride transfer/Mannich-type cyclization cascade of indole-derived pheny...
Scheme 10: Indole C5 regioselective intramolecular FC acylation of 4-substituted indoles.
Scheme 11: Catalyst-dependent regioselectivity switching in the cyclization of ethyl 2-diazo-4-(4-indolyl)-3-o...
Scheme 12: Indole C5 regioselective cyclization of α-carbonyl sulfoxonium ylides.
Scheme 13: Indole C5 regioselective cyclization of an indole-tethered donor–acceptor cyclopropane.
Scheme 14: Indole C5 regioselective epoxide–arene cyclization.
Earth-abundant 3d transition metals on the rise in catalysis
- Nikolaos Kaplaneris and
- Lutz Ackermann
Beilstein J. Org. Chem. 2022, 18, 86–88, doi:10.3762/bjoc.18.8
- transformations to form C–C and C–heteroatom bonds, thereby providing a more sustainable future for, among others, drug development in generations to come. Particularly, Nobel prize-winning palladium-catalyzed cross-coupling reactions have been recognized by the practitioners in agrochemical and pharmaceutical
A photochemical C=C cleavage process: toward access to backbone N-formyl peptides
- Haopei Wang and
- Zachary T. Ball
Beilstein J. Org. Chem. 2021, 17, 2932–2938, doi:10.3762/bjoc.17.202
- -nitroaryl compounds. Various 2-nitrobenzyl derivatives are used to photocage heteroatom functional groups, including alcohols, amines, carboxylic acids, and phosphates [11]. Typical photochemical pathways result in cleavage of a benzylic C–X bond following initial benzylic H-atom abstraction [11][13]. In
Graphical Abstract
Figure 1: Uncaging of peptide backbone N–H bonds from Chan–Lam-type modification.
Figure 2: Photocleavage of compounds 1 and 6 under basic conditions. Yield of products was calculated from cr...
Figure 3: (a) Photocleavage of compound 6 under acidic conditions. Yields determined by 1H NMR using residual...
Figure 4: Preparation and hydrolysis kinetics (inset) of N-formyl product 11. Dashed line: first-order decay ...
Figure 5: Proposed mechanism for the formation of aldehyde 3 and N-formyl product 8.
Iron-catalyzed domino coupling reactions of π-systems
- Austin Pounder and
- William Tam
Beilstein J. Org. Chem. 2021, 17, 2848–2893, doi:10.3762/bjoc.17.196
- –heteroatom bond-forming reactions. Catalysis, as a synthetic tool, is widely employed to accomplish transformations to produce many various pharmaceuticals, polymeric materials, and fine chemicals [1][2][3][4][5][6][7][8]. Catalysis is one of the fundamental pillars of green chemistry, the design of chemical
- significant development over the past 10 years. First achieved by Li and co-workers in 2007 [44], cross-dehydrogenative-coupling (CDC) reactions offer a highly atom economic approach to carbon–carbon (C–C) and carbon–heteroatom (C–X) bond formation via C–H activation [45][46]. Generally speaking, C–C bond
- discussed. Recent methods in the pursuit for efficient and economical carbon–carbon and carbon–heteroatom bond-forming reactions, such as cross-coupling, CDC, and oxidative coupling/difunctionalizations, will be summarized. The review is categorized by reaction type, and the type of bonds being formed. For
Graphical Abstract
Figure 1: Price comparison among iron and other transition metals used in catalysis.
Scheme 1: Typical modes of C–C bond formation.
Scheme 2: The components of an iron-catalyzed domino reaction.
Scheme 3: Iron-catalyzed tandem cyclization and cross-coupling reactions of iodoalkanes 1 with aryl Grignard ...
Scheme 4: Three component iron-catalyzed dicarbofunctionalization of vinyl cyclopropanes 14.
Scheme 5: Three-component iron-catalyzed dicarbofunctionalization of alkenes 21.
Scheme 6: Double carbomagnesiation of internal alkynes 31 with alkyl Grignard reagents 32.
Scheme 7: Iron-catalyzed cycloisomerization/cross-coupling of enyne derivatives 35 with alkyl Grignard reagen...
Scheme 8: Iron-catalyzed spirocyclization/cross-coupling cascade.
Scheme 9: Iron-catalyzed alkenylboration of alkenes 50.
Scheme 10: N-Alkyl–N-aryl acrylamide 60 CDC cyclization with C(sp3)–H bonds adjacent to a heteroatom.
Scheme 11: 1,2-Carboacylation of activated alkenes 60 with aldehydes 65 and alcohols 67.
Scheme 12: Iron-catalyzed dicarbonylation of activated alkenes 68 with alcohols 67.
Scheme 13: Iron-catalyzed cyanoalkylation/radical dearomatization of acrylamides 75.
Scheme 14: Synergistic photoredox/iron-catalyzed 1,2-dialkylation of alkenes 82 with common alkanes 83 and 1,3...
Scheme 15: Iron-catalyzed oxidative coupling/cyclization of phenol derivatives 86 and alkenes 87.
Scheme 16: Iron-catalyzed carbosulfonylation of activated alkenes 60.
Scheme 17: Iron-catalyzed oxidative spirocyclization of N-arylpropiolamides 91 with silanes 92 and tert-butyl ...
Scheme 18: Iron-catalyzed free radical cascade difunctionalization of unsaturated benzamides 94 with silanes 92...
Scheme 19: Iron-catalyzed cyclization of olefinic dicarbonyl compounds 97 and 100 with C(sp3)–H bonds.
Scheme 20: Radical difunctionalization of o-vinylanilides 102 with ketones and esters 103.
Scheme 21: Dehydrogenative 1,2-carboamination of alkenes 82 with alkyl nitriles 76 and amines 105.
Scheme 22: Iron-catalyzed intermolecular 1,2-difunctionalization of conjugated alkenes 107 with silanes 92 and...
Scheme 23: Four-component radical difunctionalization of chemically distinct alkenes 114/115 with aldehydes 65...
Scheme 24: Iron-catalyzed carbocarbonylation of activated alkenes 60 with carbazates 117.
Scheme 25: Iron-catalyzed radical 6-endo cyclization of dienes 119 with carbazates 117.
Scheme 26: Iron-catalyzed decarboxylative synthesis of functionalized oxindoles 130 with tert-butyl peresters ...
Scheme 27: Iron‑catalyzed decarboxylative alkylation/cyclization of cinnamamides 131/134.
Scheme 28: Iron-catalyzed carbochloromethylation of activated alkenes 60.
Scheme 29: Iron-catalyzed trifluoromethylation of dienes 142.
Scheme 30: Iron-catalyzed, silver-mediated arylalkylation of conjugated alkenes 115.
Scheme 31: Iron-catalyzed three-component carboazidation of conjugated alkenes 115 with alkanes 101/139b and t...
Scheme 32: Iron-catalyzed carboazidation of alkenes 82 and alkynes 160 with iodoalkanes 20 and trimethylsilyl ...
Scheme 33: Iron-catalyzed asymmetric carboazidation of styrene derivatives 115.
Scheme 34: Iron-catalyzed carboamination of conjugated alkenes 115 with alkyl diacyl peroxides 163 and acetoni...
Scheme 35: Iron-catalyzed carboamination using oxime esters 165 and arenes 166.
Scheme 36: Iron-catalyzed iminyl radical-triggered [5 + 2] and [5 + 1] annulation reactions with oxime esters ...
Scheme 37: Iron-catalyzed decarboxylative alkyl etherification of alkenes 108 with alcohols 67 and aliphatic a...
Scheme 38: Iron-catalyzed inter-/intramolecular alkylative cyclization of carboxylic acid and alcohol-tethered...
Scheme 39: Iron-catalyzed intermolecular trifluoromethyl-acyloxylation of styrene derivatives 115.
Scheme 40: Iron-catalyzed carboiodination of terminal alkenes and alkynes 180.
Scheme 41: Copper/iron-cocatalyzed cascade perfluoroalkylation/cyclization of 1,6-enynes 183/185.
Scheme 42: Iron-catalyzed stereoselective carbosilylation of internal alkynes 187.
Scheme 43: Synergistic photoredox/iron catalyzed difluoroalkylation–thiolation of alkenes 82.
Scheme 44: Iron-catalyzed three-component aminoazidation of alkenes 82.
Scheme 45: Iron-catalyzed intra-/intermolecular aminoazidation of alkenes 194.
Scheme 46: Stereoselective iron-catalyzed oxyazidation of enamides 196 using hypervalent iodine reagents 197.
Scheme 47: Iron-catalyzed aminooxygenation for the synthesis of unprotected amino alcohols 200.
Scheme 48: Iron-catalyzed intramolecular aminofluorination of alkenes 209.
Scheme 49: Iron-catalyzed intramolecular aminochlorination and aminobromination of alkenes 209.
Scheme 50: Iron-catalyzed intermolecular aminofluorination of alkenes 82.
Scheme 51: Iron-catalyzed aminochlorination of alkenes 82.
Scheme 52: Iron-catalyzed phosphinoylazidation of alkenes 108.
Scheme 53: Synergistic photoredox/iron-catalyzed three-component aminoselenation of trisubstituted alkenes 82.
Recent advances in the asymmetric phosphoric acid-catalyzed synthesis of axially chiral compounds
- Alemayehu Gashaw Woldegiorgis and
- Xufeng Lin
Beilstein J. Org. Chem. 2021, 17, 2729–2764, doi:10.3762/bjoc.17.185
- catalysts for a variety of enantioselective transformations, especially for carbon–carbon and carbon–heteroatom bond-forming reactions [15][28]. They are important for the development of axially chiral compounds, which are involved in the design of chiral catalysts and ligands. Currently, chiral phosphoric
Graphical Abstract
Figure 1: Representative examples of axially chiral biaryls, heterobiaryls, spiranes and allenes as ligands a...
Figure 2: Selected examples of axially chiral drugs and bioactive molecules.
Figure 3: Axially chiral functional materials and supramolecules.
Figure 4: Important chiral phosphoric acid scaffolds used in this review.
Scheme 1: Atroposelective aryl–aryl-bond formation by employing a facile [3,3]-sigmatropic rearrangement.
Scheme 2: Atroposelective synthesis of axially chiral biaryl amino alcohols 5.
Scheme 3: The enantioselective reaction of quinone and 2-naphthol derivatives.
Scheme 4: Enantioselective synthesis of multisubstituted biaryls.
Scheme 5: Enantioselective synthesis of axially chiral quinoline-derived biaryl atropisomers mediated by chir...
Scheme 6: Pd-Catalyzed atroposelective C–H olefination of biarylamines.
Scheme 7: Palladium-catalyzed directed atroposelective C–H allylation.
Scheme 8: Enantioselective synthesis of axially chiral (a) aryl indoles and (b) biaryldiols.
Scheme 9: Asymmetric arylation of indoles enabled by azo groups.
Scheme 10: Proposed mechanism for the asymmetric arylation of indoles.
Scheme 11: Enantioselective synthesis of axially chiral N-arylindoles [38].
Scheme 12: Enantioselective [3 + 2] formal cycloaddition and central-to-axial chirality conversion.
Scheme 13: Organocatalytic atroposelective arene functionalization of nitrosonaphthalene with indoles.
Scheme 14: Proposed reaction mechanism for the atroposelective arene functionalization of nitrosonaphthalenes.
Scheme 15: Asymmetric construction of axially chiral naphthylindoles [65].
Scheme 16: Enantioselective synthesis of axially chiral 3,3’-bisindoles [66].
Scheme 17: Atroposelective synthesis of 3,3’-bisiindoles bearing axial and central chirality.
Scheme 18: Enantioselective synthesis of axially chiral 3,3’-bisindoles bearing single axial chirality.
Scheme 19: Enantioselective reaction of azonaphthalenes with various pyrazolones.
Scheme 20: Enantioselective and atroposelective synthesis of axially chiral N-arylcarbazoles [73].
Scheme 21: Atroposelective cyclodehydration reaction.
Scheme 22: Atroposelective construction of axially chiral N-arylbenzimidazoles [78].
Scheme 23: Proposed reaction mechanism for the atroposelective synthesis of axially chiral N-arylbenzimidazole...
Scheme 24: Atroposelective synthesis of axially chiral arylpyrroles [21].
Scheme 25: Synthesis of axially chiral arylquinazolinones and its reaction pathway [35].
Scheme 26: Synthesis of axially chiral aryquinoline by Friedländer heteroannulation reaction and its proposed...
Scheme 27: Povarov cycloaddition–oxidative chirality conversion process.
Scheme 28: Atroposelective synthesis of oxindole-based axially chiral styrenes via kinetic resolution.
Scheme 29: Synthesis of axially chiral alkene-indole frame works [45].
Scheme 30: Proposed reaction mechanism for axially chiral alkene-indoles.
Scheme 31: Atroposelective C–H aminations of N-aryl-2-naphthylamines with azodicarboxylates.
Scheme 32: Synthesis of brominated atropisomeric N-arylquinoids.
Scheme 33: The enantioselective syntheses of axially chiral SPINOL derivatives.
Scheme 34: γ-Addition reaction of various 2,3-disubstituted indoles to β,γ-alkynyl-α-imino esters.
Scheme 35: Regio- and stereoselective γ-addition reactions of isoxazol-5(4H)-ones to β,γ-alkynyl-α-imino ester...
Scheme 36: Synthesis of chiral tetrasubstituted allenes and naphthopyrans.
Scheme 37: Asymmetric remote 1,8-conjugate additions of thiazolones and azlactones to propargyl alcohols.
Scheme 38: Synthesis of chiral allenes from 1-substituted 2-naphthols [107].
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
- sulfur atom instead of C-3', and an unnatural ʟ-configured sugar [20]. The presence of oxygen as a second heteroatom in the sugar ring was also found to result in anti-HIV activity in 1,3-dioxolane nucleosides [21]. A good example for the preparation of 2’,3’-dideoxy-3’-oxacytidine in a stereospecific
- (Figure 3). Chemical approaches Modified sugar rings containing a sulfur heteroatom at C-3' are found in medicinal chemistry. The reaction between oxygen-containing substrates (such as aldehydes or acetals) and sulfur sources (such as thiols or sulfenyl compounds) is one of the most important methods to
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.
Visible-light-mediated copper photocatalysis for organic syntheses
- Yajing Zhang,
- Qian Wang,
- Zongsheng Yan,
- Donglai Ma and
- Yuguang Zheng
Beilstein J. Org. Chem. 2021, 17, 2520–2542, doi:10.3762/bjoc.17.169
- Y to obtain the stable radical X–Y•. Subsequently, Ln−1CuI transfers one electron to X–Y• and accepts one ligand to regenerate the intermediate LnCuII and the final product [39][43] (Scheme 6). Copper photocatalysis is a powerful tool that can be used to construct carbon–heteroatom and carbon–carbon
Graphical Abstract
Scheme 1: Photoredox catalysis mechanism of [Ru(bpy)3]2+.
Scheme 2: Photoredox catalysis mechanism of CuI.
Scheme 3: Ligands and CuI complexes.
Scheme 4: Mechanism of CuI-based photocatalysis.
Scheme 5: Mechanisms of CuI–substrate complexes.
Scheme 6: Mechanism of CuII-base photocatalysis.
Scheme 7: Olefinic C–H functionalization and allylic alkylation.
Scheme 8: Cross-coupling of unactivated alkenes and CF3SO2Cl.
Scheme 9: Chlorosulfonylation/cyanofluoroalkylation of alkenes.
Scheme 10: Hydroamination of alkenes.
Scheme 11: Cross-coupling reaction of alkenes, alkyl halides with nucleophiles.
Scheme 12: Cross-coupling of alkenes with oxime esters.
Scheme 13: Oxo-azidation of vinyl arenes.
Scheme 14: Azidation/difunctionalization of vinyl arenes.
Scheme 15: Photoinitiated copper-catalyzed Sonogashira reaction.
Scheme 16: Alkyne functionalization reactions.
Scheme 17: Alkynylation of dihydroquinoxalin-2-ones with terminal alkynes.
Scheme 18: Decarboxylative alkynylation of redox-active esters.
Scheme 19: Aerobic oxidative C(sp)–S coupling reaction.
Scheme 20: Copper-catalyzed alkylation of carbazoles with alkyl halides.
Scheme 21: C–N coupling of organic halides with amides and aliphatic amines.
Scheme 22: Copper-catalyzed C–X (N, S, O) bond formation reactions.
Scheme 23: Arylation of C(sp2)–H bonds of azoles.
Scheme 24: C–C cross-coupling of aryl halides and heteroarenes.
Scheme 25: Benzylic or α-amino C–H functionalization.
Scheme 26: α-Amino C–H functionalization of aromatic amines.
Scheme 27: C–H functionalization of aromatic amines.
Scheme 28: α-Amino-C–H and alkyl C–H functionalization reactions.
Scheme 29: Other copper-photocatalyzed reactions.
Scheme 30: Cross-coupling of oxime esters with phenols or amines.
Scheme 31: Alkylation of heteroarene N-oxides.
Allylic alcohols and amines by carbenoid eliminative cross-coupling using epoxides or aziridines
- Matthew J. Fleming and
- David M. Hodgson
Beilstein J. Org. Chem. 2021, 17, 2385–2389, doi:10.3762/bjoc.17.155
- heteroatom (hydroxy, amino) functionality (Scheme 2). Results and Discussion Our studies began (Scheme 3) by reaction of BuLi (4 equiv) with a mixture of stannane 4 [6] (2 equiv) and tetramethylpiperidine (TMP, 2 equiv), to generate methoxymethyllithium and LTMP, followed by addition of terminal epoxide 5
Graphical Abstract
Scheme 1: Dimerisation of α-lithio epoxides or aziridines [3-5].
Scheme 2: Proposed eliminative cross-coupling of carbenoids to allylic alcohols (X = O) or allylic amines (X ...
Scheme 3: Allylic alcohol 6 by one-carbon homologation from epoxide 5.
Scheme 4: Internal allylic alcohols from epoxides and stannane 7.
Scheme 5: Cyclopropylidene synthesis from epoxide 5.
Scheme 6: Synthesis of vinylsilane 14.
Scheme 7: Allylic alcohol 8 from epoxide 5 and sulfone 15.
Scheme 8: Allylic amines from aziridine 17.
Scheme 9: Cyclopropylidene synthesis from aziridine 20.
Scheme 10: Cinnamylamine 23 synthesis from aziridine 17.
Scheme 11: Cinnamylamine 23 synthesis from isopropyl or neopentyl benzylic ethers 26 and 27.
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
- ‒C) and carbon–heteroatom bonds for the construction of complex organic molecules by nickel catalysis significantly improved the atom-, step-, and resource economy by avoiding the substrate prefunctionalizations (Scheme 1) [26][27][28][29][30]. The nickel-catalyzed oxidative C‒H functionalization
- (III) species 4-IX, which undergoes reductive elimination to release the desired product 10a. Concurrently, Molander and co-workers also reported a related nickel-catalyzed arylation of α-heteroatom-substituted or benzylic C(sp3)‒H bonds by aryl bromides 3 at room temperature using an iridium
- alkanes were preferentially functionalized at the 2-position due to the less steric hindrance. In addition to alkanes, a variety of ethers and amines were also compatible and selectively functionalized at the α-heteroatom positions in moderate to good yields and excellent regioselectivity. Interestingly
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.
Catalyzed and uncatalyzed procedures for the syntheses of isomeric covalent multi-indolyl hetero non-metallides: an account
- Ranadeep Talukdar
Beilstein J. Org. Chem. 2021, 17, 2102–2122, doi:10.3762/bjoc.17.137
- catalytic and uncatalytic synthetic strategies adopted for the synthesis of the non-ionic (non-metallic) versions of these important molecules till date. Keywords: bisindole; heteroatom; indole; selenide; sulfide; Introduction Indole can be considered as a “prodigy” in the family of nitrogen-based
Graphical Abstract
Scheme 1: Synthesis of 2,2’-bis(indole)borinic ester 3.
Scheme 2: Synthesis of 2,2’-bisindole NHC·boranes by an SEAr mechanism.
Scheme 3: Syntheses of indolyl amines through Buchwald–Hartwig cross coupling.
Scheme 4: Synthesis of 3,3’-bis(indolyl) ethers.
Scheme 5: C–H silylation of indoles.
Scheme 6: n-BuLi-mediated syntheses of bis(indol-3-yl)silanes.
Scheme 7: Acid-catalyzed syntheses of bis(indol-3-yl)silanes and mechanisms.
Scheme 8: B(C6F5)3 and Al(C6F5)3-catalyzed syntheses of bis(indol-3-yl)silanes reported by Han.
Scheme 9: Base-mediated syntheses of bis and tris(indol-2-yl)phosphines.
Scheme 10: Synthesis of bis(indol-2-yl)sulfides using SL2-type reagents.
Scheme 11: Synthesis of 2,3’- and 2,2’-bis(indolyl)sulfides using disulfides as substrates.
Scheme 12: Synthesis of diindol-2-ylsulfide (84) from 2-iodoindole (92) and thiourea.
Scheme 13: Synthesis of bis(indol-3-yl)sulfides using N-silylated 3-bromoindole 93.
Scheme 14: Fischer indole synthesis of bis(indol-3-yl)sulfides using thio diketones.
Scheme 15: Oxidative synthesis of bis(indol-3-yl)sulfides using indoles and elemental sulfur.
Scheme 16: Synthesis of bis(indol-3-yl)sulfides using sulfoxides as sulfur source.
Scheme 17: Syntheses of bis(indol-2-yl)selanes.
Scheme 18: Syntheses of bis(indol-3-yl)selanes.
Scheme 19: Synthesis of bis(indol-2-yl)tellane 147.
Scheme 20: Synthesis of tris(indolyl)borane 154.
Scheme 21: Synthesis of bis(indol-4-yl)amines 159.
Scheme 22: Synthesis of bis(indol-5-yl)amines.
Scheme 23: Synthesis of 6,5’/6,6’-bis(indolyl)amines.
Scheme 24: Synthesis of potent HIV-inhibitors 6,6’-bis(indolyl) ethers.
Scheme 25: Synthesis of bis(indol-7-yl) ether.
Scheme 26: Synthesis of di(indol-5-yl)sulfide (183).
Scheme 27: Syntheses of 2,2’-diformyl-7,7’-bis(indolyl)selenides.
Sustainable manganese catalysis for late-stage C–H functionalization of bioactive structural motifs
- Jongwoo Son
Beilstein J. Org. Chem. 2021, 17, 1733–1751, doi:10.3762/bjoc.17.122
- adjacent to a heteroatom, such as a nitrogen (see 22a–d) or oxygen (see 22e). Moreover, the above described manganese-catalyzed late-stage methylation process was implemented to provide methylated bioactive molecules, effectively avoiding conventionally lengthy de novo synthetic pathways (Scheme 8). The
Graphical Abstract
Scheme 1: Mn-catalyzed late-stage fluorination of sclareolide (1) and complex steroid 3.
Figure 1: Proposed reaction mechanism of C–H fluorination by a manganese porphyrin catalyst.
Scheme 2: Late-stage radiofluorination of biologically active complex molecules.
Figure 2: Proposed mechanism of C–H radiofluorination.
Scheme 3: Late-stage C–H azidation of bioactive molecules. a1.5 mol % of Mn(TMP)Cl (5) was used. bMethyl acet...
Figure 3: Proposed reaction mechanism of manganese-catalyzed C–H azidation.
Scheme 4: Mn-catalyzed late-stage C–H azidation of bioactive molecules via electrophotocatalysis. a2.5 mol % ...
Figure 4: Proposed reaction mechanism of electrophotocatalytic azidation.
Scheme 5: Manganaelectro-catalyzed late-stage azidation of bioactive molecules.
Figure 5: Proposed reaction pathway of manganaelectro-catalyzed late-stage C–H azidation.
Scheme 6: Mn-catalyzed late-stage amination of bioactive molecules. a3 Å MS were used. Protonation with HBF4⋅...
Figure 6: Proposed mechanism of manganese-catalyzed C–H amination.
Scheme 7: Mn-catalyzed C–H methylation of heterocyclic scaffolds commonly found in small-molecule drugs. aDAS...
Scheme 8: Examples of late-stage C–H methylation of bioactive molecules. aDAST activation. bFor insoluble sub...
Scheme 9: A) Mn-catalyzed late-stage C–H alkynylation of peptides. B) Intramolecular late-stage alkynylative ...
Figure 7: Proposed reaction mechanism of Mn(I)-catalyzed C–H alkynylation.
Scheme 10: Late-stage Mn-catalyzed C–H allylation of peptides and bioactive motifs.
Scheme 11: Intramolecular C–H allylative cyclic peptide formation.
Scheme 12: Late-stage C–H glycosylation of tryptophan analogues.
Scheme 13: Late-stage C–H glycosylation of tryptophan-containing peptides.
Scheme 14: Late-stage C–H alkenylation of tryptophan-containing peptides.
Scheme 15: A) Late-stage C–H macrocyclization of tryptophan-containing peptides and B) traceless removal of py...
Cerium-photocatalyzed aerobic oxidation of benzylic alcohols to aldehydes and ketones
- Girish Suresh Yedase,
- Sumit Kumar,
- Jessica Stahl,
- Burkhard König and
- Veera Reddy Yatham
Beilstein J. Org. Chem. 2021, 17, 1727–1732, doi:10.3762/bjoc.17.121
- photocatalysis has emerged as an alternative to the classical conventional synthetic methods to construct carbon–carbon and carbon–heteroatom bonds [34][35][36][37]. As a mild, efficient, and environmentally friendly approach it has the potential to unlock unique reactions that are previously inaccessible under
Graphical Abstract
Scheme 1: Photocatalyzed aerobic oxidation of aromatic alcohols.
Scheme 2: Substrate scope. Reaction conditions as given in Table 1 (entry 1). Yields are isolated yields, average of...
Scheme 3: Selective oxidation of 3-bromobenzyl alcohol in the presence of 3-phenylpropanol. Compound 1af was ...
Figure 1: Mechanistic studies. (A): UV–vis spectra of the CeIV(OBn)Cln complex in CH3CN under blue light irra...
Organocatalytic asymmetric Michael/acyl transfer reaction between α-nitroketones and 4-arylidenepyrrolidine-2,3-diones
- Chandrakanta Parida and
- Subhas Chandra Pan
Beilstein J. Org. Chem. 2021, 17, 1447–1452, doi:10.3762/bjoc.17.100
- ; pyrrolidine-2,3-dione; Introduction The Michael reaction is a powerful reaction that has been so far applied for the formation of carbon–carbon and carbon–heteroatom bonds in organic synthesis [1][2]. After the renaissance of organocatalysis in the year 2000, this field has been applied tremendously for the
Graphical Abstract
Scheme 1: Reactions of α-nitroketones with unsaturated pyrazolone and with 4-benzylidenepyrrolidine-2,3-dione....
Scheme 2: Reaction of 4-benzylidenedihydrofuran-2,3-dione (4) with α-nitroketones 2b,c. Reaction conditions: ...
Fritsch–Buttenberg–Wiechell rearrangement of magnesium alkylidene carbenoids leading to the formation of alkynes
- Tsutomu Kimura,
- Koto Sekiguchi,
- Akane Ando and
- Aki Imafuji
Beilstein J. Org. Chem. 2021, 17, 1352–1359, doi:10.3762/bjoc.17.94
- Tsutomu Kimura Koto Sekiguchi Akane Ando Aki Imafuji Department of Chemistry, Graduate School of Science, Tokyo University of Science, 1-3 Kagurazaka, Shinjuku-ku, Tokyo 162-8601, Japan 10.3762/bjoc.17.94 Abstract A series of 1-heteroatom-substituted vinyl p-tolyl sulfoxides were prepared and
- rearrangement of magnesium alkylidene carbenoids 3 by using 13C-labeled sulfoxides and by using DFT calculations is also described. Results and Discussion Synthesis of 1-heteroatom-substituted vinyl p-tolyl sulfoxides As magnesium alkylidene carbenoid precursors, a series of 1-heteroatom-substituted vinyl p
- of 1-heteroatom-substituted vinylmetals is dependent on the type of the metal and the heteroatom substituent [18][19]. The vinylidene character of 1-heteroatom-substituted vinylmetals is estimated to increase in the following order (1-methoxyvinyl)magnesium chloride, CH2=C(OMe)MgCl < (1-halovinyl
Graphical Abstract
Scheme 1: Synthesis of alkynes from carbonyl compounds through one-carbon homologation.
Scheme 2: Reactions of magnesium alkylidene carbenoids 3, generated from sulfoxides 2 and iPrMgCl.
Scheme 3: Synthesis of sulfoxides 2 and 5–8 from carbonyl compounds 1.
Scheme 4: Reaction of sulfoxides 5 and 6 with isopropylmagnesium chloride.
Scheme 5: Reaction of sulfoxide 2c with isopropylmagnesium chloride.
Scheme 6: Reaction of 13C-labeled sulfoxides [13C]-(E)-2e and [13C]-(Z)-2e with iPrMgCl.
Scheme 7: A plausible reaction mechanism for the formation of alkynes 4. a) 1,2-Rearrangement readily takes p...
Figure 1: Optimized geometries of reactant (E)-3e, transition state (E)-3e‡, and product 4e·MgCl2 for the FBW...
A comprehensive review of flow chemistry techniques tailored to the flavours and fragrances industries
- Guido Gambacorta,
- James S. Sharley and
- Ian R. Baxendale
Beilstein J. Org. Chem. 2021, 17, 1181–1312, doi:10.3762/bjoc.17.90
Graphical Abstract
Figure 1: Representative shares of the global F&F market (2018) segmented on their applications [1].
Figure 2: General structure of an international fragrance company [2].
Figure 3: The Michael Edwards fragrance wheel.
Figure 4: Examples of oriental (1–3), woody (4–7), fresh (8–10), and floral (11 and 12) notes.
Figure 5: A basic depiction of batch vs flow.
Scheme 1: Examples of reactions for which flow processing outperforms batch.
Scheme 2: Some industrially important aldol-based transformations.
Scheme 3: Biphasic continuous aldol reactions of acetone and various aldehydes.
Scheme 4: Aldol synthesis of 43 in flow using LiHMDS as the base.
Scheme 5: A semi-continuous synthesis of doravirine (49) involving a key aldol reaction.
Scheme 6: Enantioselective aldol reaction using 5-(pyrrolidin-2-yl)tetrazole (51) as catalyst in a microreact...
Scheme 7: Gröger's example of asymmetric aldol reaction in aqueous media.
Figure 6: Immobilised reagent column reactor types.
Scheme 8: Photoinduced thiol–ene coupling preparation of silica-supported 5-(pyrrolidin-2-yl)tetrazole 63 and...
Scheme 9: Continuous-flow approach for enantioselective aldol reactions using the supported catalyst 67.
Scheme 10: Ötvös’ employment of a solid-supported peptide aldol catalyst in flow.
Scheme 11: The use of proline tetrazole packed in a column for aldol reaction between cyclohexanone (65) and 2...
Scheme 12: Schematic diagram of an aminosilane-grafted Si-Zr-Ti/PAI-HF reactor for continuous-flow aldol and n...
Scheme 13: Continuous-flow condensation for the synthesis of the intermediate 76 to nabumetone (77) and Microi...
Scheme 14: Synthesis of ψ-Ionone (80) in continuous-flow via aldol condensation between citral (79) and aceton...
Scheme 15: Synthesis of β-methyl-ionones (83) from citral (79) in flow. The steps are separately described, an...
Scheme 16: Continuous-flow synthesis of 85 from 84 described by Gavriilidis et al.
Scheme 17: Continuous-flow scCO2 apparatus for the synthesis of 2-methylpentanal (87) and the self-condensed u...
Scheme 18: Chen’s two-step flow synthesis of coumarin (90).
Scheme 19: Pechmann condensation for the synthesis of 7-hydroxyxcoumarin (93) in flow. The setup extended to c...
Scheme 20: Synthesis of the dihydrojasmonate 35 exploiting nitro derivative proposed by Ballini et al.
Scheme 21: Silica-supported amines as heterogeneous catalyst for nitroaldol condensation in flow.
Scheme 22: Flow apparatus for the nitroaldol condensation of p-hydroxybenzaldehyde (102) to nitrostyrene 103 a...
Scheme 23: Nitroaldol reaction of 64 to 105 employing a quaternary ammonium functionalised PANF.
Scheme 24: Enantioselective nitroaldol condensation for the synthesis of 108 under flow conditions.
Scheme 25: Enatioselective synthesis of 1,2-aminoalcohol 110 via a copper-catalysed nitroaldol condensation.
Scheme 26: Examples of Knoevenagel condensations applied for fragrance components.
Scheme 27: Flow apparatus for Knoevenagel condensation described in 1989 by Venturello et al.
Scheme 28: Knoevenagel reaction using a coated multichannel membrane microreactor.
Scheme 29: Continuous-flow apparatus for Knoevenagel condensation employing sugar cane bagasse as support deve...
Scheme 30: Knoevenagel reaction for the synthesis of 131–135 in flow using an amine-functionalised silica gel. ...
Scheme 31: Continuous-flow synthesis of compound 137, a key intermediate for the synthesis of pregabalin (138)...
Scheme 32: Continuous solvent-free apparatus applied for the synthesis of compounds 140–143 using a TSE. Throu...
Scheme 33: Lewis et al. developed a spinning disc reactor for Darzens condensation of 144 and a ketone to furn...
Scheme 34: Some key industrial applications of conjugate additions in the F&F industry.
Scheme 35: Continuous-flow synthesis of 4-(2-hydroxyethyl)thiomorpholine 1,1-dioxide (156) via double conjugat...
Scheme 36: Continuous-flow system for Michael addition using CsF on alumina as the catalyst.
Scheme 37: Calcium chloride-catalysed asymmetric Michael addition using an immobilised chiral ligand.
Scheme 38: Continuous multistep synthesis for the preparation of (R)-rolipram (173). Si-NH2: primary amine-fun...
Scheme 39: Continuous-flow Michael addition using ion exchange resin Amberlyst® A26.
Scheme 40: Preparation of the heterogeneous catalyst 181 developed by Paixão et al. exploiting Ugi multicompon...
Scheme 41: Continuous-flow system developed by the Paixão’s group for the preparation of Michael asymmetric ad...
Scheme 42: Continuous-flow synthesis of nitroaldols catalysed by supported catalyst 184 developed by Wennemers...
Scheme 43: Heterogenous polystyrene-supported catalysts developed by Pericàs and co-workers.
Scheme 44: PANF-supported pyrrolidine catalyst for the conjugate addition of cyclohexanone (65) and trans-β-ni...
Scheme 45: Synthesis of (−)-paroxetine precursor 195 developed by Ötvös, Pericàs, and Kappe.
Scheme 46: Continuous-flow approach for the 5-step synthesis of (−)-oseltamivir (201) as devised by Hayashi an...
Scheme 47: Continuous-flow enzyme-catalysed Michael addition.
Scheme 48: Continuous-flow copper-catalysed 1,4 conjugate addition of Grignard reagents to enones. Reprinted w...
Scheme 49: A collection of commonly encountered hydrogenation reactions.
Figure 7: The ThalesNano H-Cube® continuous-flow hydrogenator.
Scheme 50: Chemoselective reduction of an α,β-unsaturated ketone using the H-Cube® reactor.
Scheme 51: Incorporation of Lindlar’s catalyst into the H-Cube® reactor for the reduction of an alkyne.
Scheme 52: Continuous-flow semi-hydrogenation of alkyne 208 to 209 using SACs with H-Cube® system.
Figure 8: The standard setups for tube-in-tube gas–liquid reactor units.
Scheme 53: Homogeneous hydrogenation of olefins using a tube-in-tube reactor setup.
Scheme 54: Recyclable heterogeneous flow hydrogenation system.
Scheme 55: Leadbeater’s reverse tube-in-tube hydrogenation system for olefin reductions.
Scheme 56: a) Hydrogenation using a Pd-immobilised microchannel reactor (MCR) and b) a representation of the i...
Scheme 57: Hydrogenation of alkyne 238 exploiting segmented flow in a Pd-immobilised capillary reactor.
Scheme 58: Continuous hydrogenation system for the preparation of cyrene (241) from (−)-levoglucosenone (240).
Scheme 59: Continuous hydrogenation system based on CSMs developed by Hornung et al.
Scheme 60: Chemoselective reduction of carbonyls (ketones over aldehydes) in flow.
Scheme 61: Continuous system for the semi-hydrogenation of 256 and 258, developed by Galarneau et al.
Scheme 62: Continuous synthesis of biodiesel fuel 261 from lignin-derived furfural acetone (260).
Scheme 63: Continuous synthesis of γ-valerolacetone (263) via CTH developed by Pineda et al.
Scheme 64: Continuous hydrogenation of lignin-derived biomass (products 265, 266, and 267) using a sustainable...
Scheme 65: Ru/C or Rh/C-catalysed hydrogenation of arene in flow as developed by Sajiki et al.
Scheme 66: Polysilane-immobilized Rh–Pt-catalysed hydrogenation of arenes in flow by Kobayashi et al.
Scheme 67: High-pressure in-line mixing of H2 for the asymmetric reduction of 278 at pilot scale with a 73 L p...
Figure 9: Picture of the PFR employed at Eli Lilly & Co. for the continuous hydrogenation of 278 [287]. Reprinted ...
Scheme 68: Continuous-flow asymmetric hydrogenation using Oppolzer's sultam 280 as chiral auxiliary.
Scheme 69: Some examples of industrially important oxidation reactions in the F&F industry. CFL: compact fluor...
Scheme 70: Gold-catalysed heterogeneous oxidation of alcohols in flow.
Scheme 71: Uozumi’s ARP-Pt flow oxidation protocol.
Scheme 72: High-throughput screening of aldehyde oxidation in flow using an in-line GC.
Scheme 73: Permanganate-mediated Nef oxidation of nitroalkanes in flow with the use of in-line sonication to p...
Scheme 74: Continuous-flow aerobic anti-Markovnikov Wacker oxidation.
Scheme 75: Continuous-flow oxidation of 2-benzylpyridine (312) using air as the oxidant.
Scheme 76: Continuous-flow photo-oxygenation of monoterpenes.
Scheme 77: A tubular reactor design for flow photo-oxygenation.
Scheme 78: Glucose oxidase (GOx)-mediated continuous oxidation of glucose using compressed air and the FFMR re...
Scheme 79: Schematic continuous-flow sodium hypochlorite/TEMPO oxidation of alcohols.
Scheme 80: Oxidation using immobilised TEMPO (344) was developed by McQuade et al.
Scheme 81: General protocol for the bleach/catalytic TBAB oxidation of aldehydes and alcohols.
Scheme 82: Continuous-flow PTC-assisted oxidation using hydrogen peroxide. The process was easily scaled up by...
Scheme 83: Continuous-flow epoxidation of cyclohexene (348) and in situ preparation of m-CPBA.
Scheme 84: Continuous-flow epoxidation using DMDO as oxidant.
Scheme 85: Mukayama aerobic epoxidation optimised in flow mode by the Favre-Réguillon group.
Scheme 86: Continuous-flow asymmetric epoxidation of derivatives of 359 exploiting a biomimetic iron catalyst.
Scheme 87: Continuous-flow enzymatic epoxidation of alkenes developed by Watts et al.
Scheme 88: Engineered multichannel microreactor for continuous-flow ozonolysis of 366.
Scheme 89: Continuous-flow synthesis of the vitamin D precursor 368 using multichannel microreactors. MFC: mas...
Scheme 90: Continuous ozonolysis setup used by Kappe et al. for the synthesis of various substrates employing ...
Scheme 91: Continuous-flow apparatus for ozonolysis as developed by Ley et al.
Scheme 92: Continuous-flow ozonolysis for synthesis of vanillin (2) using a film-shear flow reactor.
Scheme 93: Examples of preparative methods for ajoene (386) and allicin (388).
Scheme 94: Continuous-flow oxidation of thioanisole (389) using styrene-based polymer-supported peroxytungstat...
Scheme 95: Continuous oxidation of thiosulfinates using Oxone®-packed reactor.
Scheme 96: Continuous-flow electrochemical oxidation of thioethers.
Scheme 97: Continuous-flow oxidation of 400 to cinnamophenone (235).
Scheme 98: Continuous-flow synthesis of dehydrated material 401 via oxidation of methyl dihydrojasmonate (33).
Scheme 99: Some industrially important transformations involving Grignard reagents.
Scheme 100: Grachev et al. apparatus for continuous preparation of Grignard reagents.
Scheme 101: Example of fluidized Mg bed reactor with NMR spectrometer as on-line monitoring system.
Scheme 102: Continuous-flow synthesis of Grignard reagents and subsequent quenching reaction.
Figure 10: Membrane-based, liquid–liquid separator with integrated pressure control [52]. Adapted with permission ...
Scheme 103: Continuous-flow synthesis of 458, an intermediate to fluconazole (459).
Scheme 104: Continuous-flow synthesis of ketones starting from benzoyl chlorides.
Scheme 105: A Grignard alkylation combining CSTR and PFR technologies with in-line infrared reaction monitoring....
Scheme 106: Continuous-flow preparation of 469 from Grignard addition of methylmagnesium bromide.
Scheme 107: Continuous-flow synthesis of Grignard reagents 471.
Scheme 108: Preparation of the Grignard reagent 471 using CSTR and the continuous process for synthesis of the ...
Scheme 109: Continuous process for carboxylation of Grignard reagents in flow using tube-in-tube technology.
Scheme 110: Continuous synthesis of propargylic alcohols via ethynyl-Grignard reagent.
Scheme 111: Silica-supported catalysed enantioselective arylation of aldehydes using Grignard reagents in flow ...
Scheme 112: Acid-catalysed rearrangement of citral and dehydrolinalool derivatives.
Scheme 113: Continuous stilbene isomerisation with continuous recycling of photoredox catalyst.
Scheme 114: Continuous-flow synthesis of compound 494 as developed by Ley et al.
Scheme 115: Selected industrial applications of DA reaction.
Scheme 116: Multistep flow synthesis of the spirocyclic structure 505 via employing DA cycloaddition.
Scheme 117: Continuous-flow DA reaction developed in a plater flow reactor for the preparation of the adduct 508...
Scheme 118: Continuous-flow DA reaction using a silica-supported imidazolidinone organocatalyst.
Scheme 119: Batch vs flow for the DA reaction of (cyclohexa-1,5-dien-1-yloxy)trimethylsilane (513) with acrylon...
Scheme 120: Continuous-flow DA reaction between 510 and 515 using a shell-core droplet system.
Scheme 121: Continuous-flow synthesis of bicyclic systems from benzyne precursors.
Scheme 122: Continuous-flow synthesis of bicyclic scaffolds 527 and 528 for further development of potential ph...
Scheme 123: Continuous-flow inverse-electron hetero-DA reaction to pyridine derivatives such as 531.
Scheme 124: Comparison between batch and flow for the synthesis of pyrimidinones 532–536 via retro-DA reaction ...
Scheme 125: Continuous-flow coupled with ultrasonic system for preparation of ʟ-ascorbic acid derivatives 539 d...
Scheme 126: Two-step continuous-flow synthesis of triazole 543.
Scheme 127: Continuous-flow preparation of triazoles via CuAAC employing 546-based heterogeneous catalyst.
Scheme 128: Continuous-flow synthesis of compounds 558 through A3-coupling and 560 via AgAAC both employing the...
Scheme 129: Continuous-flow photoinduced [2 + 2] cycloaddition for the preparation of bicyclic derivatives of 5...
Scheme 130: Continuous-flow [2 + 2] and [5 + 2] cycloaddition on large scale employing a flow reactor developed...
Scheme 131: Continuous-flow preparation of the tricyclic structures 573 and 574 starting from pyrrole 570 via [...
Scheme 132: Continuous-flow [2 + 2] photocyclization of cinnamates.
Scheme 133: Continuous-flow preparation of cyclobutane 580 on a 5-plates photoreactor.
Scheme 134: Continuous-flow [2 + 2] photocycloaddition under white LED lamp using heterogeneous PCN as photocat...
Figure 11: Picture of the parallel tube flow reactor (PTFR) "The Firefly" developed by Booker-Milburn et al. a...
Scheme 135: Continuous-flow acid-catalysed [2 + 2] cycloaddition between silyl enol ethers and acrylic esters.
Scheme 136: Continuous synthesis of lactam 602 using glass column reactors.
Scheme 137: In situ generation of ketenes for the Staudinger lactam synthesis developed by Ley and Hafner.
Scheme 138: Application of [2 + 2 + 2] cycloadditions in flow employed by Ley et al.
Scheme 139: Examples of FC reactions applied in F&F industry.
Scheme 140: Continuous-flow synthesis of ibuprofen developed by McQuade et al.
Scheme 141: The FC acylation step of Jamison’s three-step ibuprofen synthesis.
Scheme 142: Synthesis of naphthalene derivative 629 via FC acylation in microreactors.
Scheme 143: Flow system for rapid screening of catalysts and reaction conditions developed by Weber et al.
Scheme 144: Continuous-flow system developed by Buorne, Muller et al. for DSD optimisation of the FC acylation ...
Scheme 145: Continuous-flow FC acylation of alkynes to yield β-chlorovinyl ketones such as 638.
Scheme 146: Continuous-flow synthesis of tonalide (619) developed by Wang et al.
Scheme 147: Continuous-flow preparation of acylated arene such as 290 employing Zr4+-β-zeolite developed by Kob...
Scheme 148: Flow system applied on an Aza-FC reaction catalysed by the thiourea catalyst 648.
Scheme 149: Continuous hydroformylation in scCO2.
Scheme 150: Two-step flow synthesis of aldehyde 655 through a sequential Heck reaction and subsequent hydroform...
Scheme 151: Single-droplet (above) and continuous (below) flow reactors developed by Abolhasani et al. for the ...
Scheme 152: Continuous hydroformylation of 1-dodecene (655) using a PFR-CSTR system developed by Sundmacher et ...
Scheme 153: Continuous-flow synthesis of the aldehyde 660 developed by Eli Lilly & Co. [32]. Adapted with permissio...
Scheme 154: Continuous asymmetric hydroformylation employing heterogenous catalst supported on carbon-based sup...
Scheme 155: Examples of acetylation in F&F industry: synthesis of bornyl (S,R,S-664) and isobornyl (S,S,S-664) ...
Scheme 156: Continuous-flow preparation of bornyl acetate (S,R,S-664) employing the oscillating flow reactor.
Scheme 157: Continuous-flow synthesis of geranyl acetate (666) from acetylation of geraniol (343) developed by ...
Scheme 158: 12-Ttungstosilicic acid-supported silica monolith-catalysed acetylation in flow.
Scheme 159: Continuous-flow preparation of cyclopentenone 676.
Scheme 160: Two-stage synthesis of coumarin (90) via acetylation of salicylaldehyde (88).
Scheme 161: Intensification process for acetylation of 5-methoxytryptamine (677) to melatonin (678) developed b...
Scheme 162: Examples of macrocyclic musky odorants both natural (679–681) and synthetic (682 and 683).
Scheme 163: Flow setup combined with microwave for the synthesis of macrocycle 686 via RCM.
Scheme 164: Continuous synthesis of 2,5-dihydro-1H-pyrroles via ring-closing metathesis.
Scheme 165: Continuous-flow metathesis of 485 developed by Leadbeater et al.
Figure 12: Comparison between RCM performed using different routes for the preparation of 696. On the left the...
Scheme 166: Continuous-flow RCM of 697 employed the solid-supported catalyst 698 developed by Grela, Kirschning...
Scheme 167: Continuous-flow RORCM of cyclooctene employing the silica-absorbed catalyst 700.
Scheme 168: Continuous-flow self-metathesis of methyl oleate (703) employing SILP catalyst 704.
Scheme 169: Flow apparatus for the RCM of 697 using a nanofiltration membrane for the recovery and reuse of the...
Scheme 170: Comparison of loadings between RCMs performed with different routes for the synthesis of 709.
Synthetic reactions driven by electron-donor–acceptor (EDA) complexes
- Zhonglie Yang,
- Yutong Liu,
- Kun Cao,
- Xiaobin Zhang,
- Hezhong Jiang and
- Jiahong Li
Beilstein J. Org. Chem. 2021, 17, 771–799, doi:10.3762/bjoc.17.67
- has attracted more and more chemists and provided new opportunities for synthetic chemistry [8]. Moreover, diverse photocatalyst-free photochemical reactions have been employed to construct carbon–carbon and carbon–heteroatom bonds [9]. Among these methods, the product formations by aid of EDA
Graphical Abstract
Scheme 1: The electron transfer process in EDA complexes.
Scheme 2: Synthesis of benzo[b]phosphorus oxide 3 initiated by an EDA complex.
Scheme 3: Mechanism of the synthesis of quinoxaline derivative 7.
Scheme 4: Synthesis of imidazole derivative 10 initiated by an EDA complex.
Scheme 5: Synthesis of sulfamoylation product 12 initiated by an EDA complex.
Scheme 6: Mechanism of the synthesis of sulfamoylation product 12.
Scheme 7: Synthesis of indole derivative 22 initiated by an EDA complex.
Scheme 8: Synthesis of perfluoroalkylated pyrimidines 26 initiated by an EDA complex.
Scheme 9: Synthesis of phenanthridine derivative 29 initiated by an EDA complex.
Scheme 10: Synthesis of cis-tetrahydroquinoline derivative 32 initiated by an EDA complex.
Scheme 11: Mechanism of the synthesis of cis-tetrahydroquinoline derivative 32.
Scheme 12: Synthesis of phenanthridine derivative 38 initiated by an EDA complex.
Scheme 13: Synthesis of spiropyrroline derivative 40 initiated by an EDA complex.
Scheme 14: Synthesis of benzothiazole derivative 43 initiated by an EDA complex.
Scheme 15: Synthesis of perfluoroalkyl-s-triazine derivative 45 initiated by an EDA complex.
Scheme 16: Synthesis of indoline derivative 47 initiated by an EDA complex.
Scheme 17: Mechanism of the synthesis of spirocyclic indoline derivative 47.
Scheme 18: Synthesis of cyclobutane product 50 initiated by an EDA complex.
Scheme 19: Mechanism of the synthesis of spirocyclic indoline derivative 50.
Scheme 20: Synthesis of 1,3-oxazolidine compound 59 initiated by an EDA complex.
Scheme 21: Synthesis of trifluoromethylated product 61 initiated by an EDA complex.
Scheme 22: Synthesis of indole alkylation product 64 initiated by an EDA complex.
Scheme 23: Synthesis of perfluoroalkylation product 67 initiated by an EDA complex.
Scheme 24: Synthesis of hydrotrifluoromethylated product 70 initiated by an EDA complex.
Scheme 25: Synthesis of β-trifluoromethylated alkyne product 71 initiated by an EDA complex.
Scheme 26: Mechanism of the synthesis of 2-phenylthiophene derivative 74.
Scheme 27: Synthesis of allylated product 80 initiated by an EDA complex.
Scheme 28: Synthesis of trifluoromethyl-substituted alkynyl product 84 initiated by an EDA complex.
Scheme 29: Synthesis of dearomatized fluoroalkylation product 86 initiated by an EDA complex.
Scheme 30: Mechanism of the synthesis of dearomatized fluoroalkylation product 86.
Scheme 31: Synthesis of C(sp3)–H allylation product 91 initiated by an EDA complex.
Scheme 32: Synthesis of perfluoroalkylation product 93 initiated by an EDA complex.
Scheme 33: Synthesis of spirocyclic indolene derivative 95 initiated by an EDA complex.
Scheme 34: Synthesis of perfluoroalkylation product 97 initiated by an EDA complex.
Scheme 35: Synthesis of alkylated indole derivative 100 initiated by an EDA complex.
Scheme 36: Mechanism of the synthesis of alkylated indole derivative 100.
Scheme 37: Synthesis of arylated oxidized indole derivative 108 initiated by an EDA complex.
Scheme 38: Synthesis of 4-ketoaldehyde derivative 111 initiated by an EDA complex.
Scheme 39: Mechanism of the synthesis of 4-ketoaldehyde derivative 111.
Scheme 40: Synthesis of perfluoroalkylated olefin 118 initiated by an EDA complex.
Scheme 41: Synthesis of alkylation product 121 initiated by an EDA complex.
Scheme 42: Synthesis of acylation product 123 initiated by an EDA complex.
Scheme 43: Mechanism of the synthesis of acylation product 123.
Scheme 44: Synthesis of trifluoromethylation product 126 initiated by an EDA complex.
Scheme 45: Synthesis of unnatural α-amino acid 129 initiated by an EDA complex.
Scheme 46: Synthesis of thioether derivative 132 initiated by an EDA complex.
Scheme 47: Synthesis of S-aryl dithiocarbamate product 135 initiated by an EDA complex.
Scheme 48: Mechanism of the synthesis of S-aryl dithiocarbamate product 135.
Scheme 49: Synthesis of thioether product 141 initiated by an EDA complex.
Scheme 50: Mechanism of the synthesis of borate product 144.
Scheme 51: Synthesis of boronation product 148 initiated by an EDA complex.
Scheme 52: Synthesis of boration product 151 initiated by an EDA complex.
Scheme 53: Synthesis of boronic acid ester derivative 154 initiated by an EDA complex.
Scheme 54: Synthesis of β-azide product 157 initiated by an EDA complex.
Scheme 55: Decarboxylation reaction initiated by an EDA complex.
Scheme 56: Synthesis of amidated product 162 initiated by an EDA complex.
Scheme 57: Synthesis of diethyl phenylphosphonate 165 initiated by an EDA complex.
Scheme 58: Mechanism of the synthesis of diethyl phenylphosphonate derivative 165.
Scheme 59: Synthesis of (Z)-2-iodovinyl phenyl ether 168 initiated by an EDA complex.
Scheme 60: Mechanism of the synthesis of (Z)-2-iodovinyl phenyl ether derivative 168.
Scheme 61: Dehalogenation reaction initiated by an EDA complex.
Deoxygenative C2-heteroarylation of quinoline N-oxides: facile access to α-triazolylquinolines
- Geetanjali S. Sontakke,
- Rahul K. Shukla and
- Chandra M. R. Volla
Beilstein J. Org. Chem. 2021, 17, 485–493, doi:10.3762/bjoc.17.42
- heteroatom-tethered triazoles. The -O-, -S- and -N-linked triazoles smoothly reacted under standard reaction conditions to provide the corresponding functionalized C2-triazolylquinolines 3q–x in 67–83% yield. Cyclohexadienone-tethered triazole afforded the corresponding product 3y in 66% yield. It is worth
Graphical Abstract
Figure 1: Bioactive molecules containing the 2-aminoquinoline motif.
Scheme 1: C2-selective C–N bond formation of N-oxides.
Scheme 2: Substrate scope of N-sulfonyl-1,2,3-triazoles. Reaction conditions: 1a (0.2 mmol), 2 (0.24 mmol) an...
Scheme 3: Substrate scope of quinoline N-oxides. Reaction conditions: 1 (0.2 mmol), 2a (0.24 mmol) and DCE (2...
Scheme 4: Late-stage modification of natural products.
Scheme 5: Substrate scope for the reaction of substituted triazoles with isoquinoline N-oxide.
Scheme 6: Gram-scale and one-pot synthesis.
Scheme 7: Proposed mechanism.
