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Search for "sulfones" in Full Text gives 85 result(s) in Beilstein Journal of Organic Chemistry.
When metal-catalyzed C–H functionalization meets visible-light photocatalysis
- Lucas Guillemard and
- Joanna Wencel-Delord
Beilstein J. Org. Chem. 2020, 16, 1754–1804, doi:10.3762/bjoc.16.147
- aromatic coupling partner, including frequently used Weinreb amides or functionalized secondary and primary amides. Regarding the scope of olefin substrates, the reaction tolerated numerous functional groups including acrylates, vinyl silanes or sulfones which was interesting from the post
Graphical Abstract
Figure 1: Concept of dual synergistic catalysis.
Figure 2: Classification of catalytic systems involving two catalysts.
Figure 3: General mechanism for the dual nickel/photoredox catalytic system.
Figure 4: General mechanisms for C–H activation catalysis involving different reoxidation strategies.
Figure 5: Indole synthesis via dual C–H activation/photoredox catalysis.
Figure 6: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 7: Oxidative Heck reaction on arenes via the dual catalysis.
Figure 8: Proposed mechanism for the Heck reaction on arenes via dual catalysis.
Figure 9: Oxidative Heck reaction on phenols via the dual catalysis.
Figure 10: Proposed mechanism for the Heck reaction on phenols via dual catalysis.
Figure 11: Carbazole synthesis via dual C–H activation/photoredox catalysis.
Figure 12: Proposed mechanism for the carbazole synthesis via dual catalysis.
Figure 13: Carbonylation of enamides via the dual C–H activation/photoredox catalysis.
Figure 14: Proposed mechanism for carbonylation of enamides via dual catalysis.
Figure 15: Annulation of benzamides via the dual C–H activation/photoredox catalysis.
Figure 16: Proposed mechanism for the annulation of benzamides via dual catalysis.
Figure 17: Synthesis of indoles via the dual C–H activation/photoredox catalysis.
Figure 18: Proposed mechanism for the indole synthesis via dual catalysis.
Figure 19: General concept of dual catalysis merging C–H activation and photoredox catalysis.
Figure 20: The first example of dual catalysis merging C–H activation and photoredox catalysis.
Figure 21: Proposed mechanism for the C–H arylation with diazonium salts via dual catalysis.
Figure 22: Dual catalysis merging C–H activation/photoredox using diaryliodonium salts.
Figure 23: Direct arylation via the dual catalytic system reported by Xu.
Figure 24: Direct arylation via dual catalytic system reported by Balaraman.
Figure 25: Direct arylation via dual catalytic system reported by Guo.
Figure 26: C(sp3)–H bond arylation via the dual Pd/photoredox catalytic system.
Figure 27: Acetanilide derivatives acylation via the dual C–H activation/photoredox catalysis.
Figure 28: Proposed mechanism for the C–H acylation with α-ketoacids via dual catalysis.
Figure 29: Acylation of azobenzenes via the dual catalysis C–H activation/photoredox.
Figure 30: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 31: Proposed mechanism for the C2-acylation of indoles with aldehydes via dual catalysis.
Figure 32: C2-acylation of indoles via the dual C–H activation/photoredox catalysis.
Figure 33: Perfluoroalkylation of arenes via the dual C–H activation/photoredox catalysis.
Figure 34: Proposed mechanism for perfluoroalkylation of arenes via dual catalysis.
Figure 35: Sulfonylation of 1-naphthylamides via the dual C–H activation/photoredox catalysis.
Figure 36: Proposed mechanism for sulfonylation of 1-naphthylamides via dual catalysis.
Figure 37: meta-C–H Alkylation of arenes via visible-light metallaphotocatalysis.
Figure 38: Alternative procedure for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 39: Proposed mechanism for meta-C–H alkylation of arenes via metallaphotocatalysis.
Figure 40: C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 41: Proposed mechanism for C–H borylation of arenes via visible-light metallaphotocatalysis.
Figure 42: Undirected C–H aryl–aryl cross coupling via dual gold/photoredox catalysis.
Figure 43: Proposed mechanism for the undirected C–H aryl–aryl cross-coupling via dual catalysis.
Figure 44: Undirected C–H arylation of (hetero)arenes via dual manganese/photoredox catalysis.
Figure 45: Proposed mechanism for the undirected arylation of (hetero)arenes via dual catalysis.
Figure 46: Photoinduced C–H arylation of azoles via copper catalysis.
Figure 47: Photo-induced C–H chalcogenation of azoles via copper catalysis.
Figure 48: Decarboxylative C–H adamantylation of azoles via dual cobalt/photoredox catalysis.
Figure 49: Proposed mechanism for the C–H adamantylation of azoles via dual catalysis.
Figure 50: General mechanisms for the “classical” (left) and Cu-free variant (right) Sonogoshira reaction.
Figure 51: First example of a dual palladium/photoredox catalysis for Sonogashira-type couplings.
Figure 52: Arylation of terminal alkynes with diazonium salts via dual gold/photoredox catalysis.
Figure 53: Proposed mechanism for the arylation of terminal alkynes via dual catalysis.
Figure 54: C–H Alkylation of alcohols promoted by H-atom transfer (HAT).
Figure 55: Proposed mechanism for the C–H alkylation of alcohols promoted by HAT.
Figure 56: C(sp3)–H arylation of latent nucleophiles promoted by H-atom transfer.
Figure 57: Proposed mechanism for the C(sp3)–H arylation of latent nucleophiles promoted by HAT.
Figure 58: Direct α-arylation of alcohols promoted by H-atom transfer.
Figure 59: Proposed mechanism for the direct α-arylation of alcohols promoted by HAT.
Figure 60: C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 61: Proposed mechanism for the C–H arylation of amines via dual Ni/photoredox catalysis.
Figure 62: C–H functionalization of nucleophiles via excited ketone/nickel dual catalysis.
Figure 63: Proposed mechanism for the C–H functionalization enabled by excited ketones.
Figure 64: Selective sp3–sp3 cross-coupling promoted by H-atom transfer.
Figure 65: Proposed mechanism for the selective sp3–sp3 cross-coupling promoted by HAT.
Figure 66: Direct C(sp3)–H acylation of amines via dual Ni/photoredox catalysis.
Figure 67: Proposed mechanism for the C–H acylation of amines via dual Ni/photoredox catalysis.
Figure 68: C–H hydroalkylation of internal alkynes via dual Ni/photoredox catalysis.
Figure 69: Proposed mechanism for the C–H hydroalkylation of internal alkynes.
Figure 70: Alternative procedure for the C–H hydroalkylation of ynones, ynoates, and ynamides.
Figure 71: Allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 72: Proposed mechanism for the allylic C(sp3)–H activation via dual Ni/photoredox catalysis.
Figure 73: Asymmetric allylation of aldehydes via dual Cr/photoredox catalysis.
Figure 74: Proposed mechanism for the asymmetric allylation of aldehydes via dual catalysis.
Figure 75: Aldehyde C–H functionalization promoted by H-atom transfer.
Figure 76: Proposed mechanism for the C–H functionalization of aldehydes promoted by HAT.
Figure 77: Direct C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 78: Proposed mechanism for the C–H arylation of strong aliphatic bonds promoted by HAT.
Figure 79: Direct C–H trifluoromethylation of strong aliphatic bonds promoted by HAT.
Figure 80: Proposed mechanism for the C–H trifluoromethylation of strong aliphatic bonds.
Photocatalyzed syntheses of phenanthrenes and their aza-analogues. A review
- Alessandra Del Tito,
- Havall Othman Abdulla,
- Davide Ravelli,
- Stefano Protti and
- Maurizio Fagnoni
Beilstein J. Org. Chem. 2020, 16, 1476–1488, doi:10.3762/bjoc.16.123
- desired trifluoromethylated products 7.3a–d in satisfactory yields (Scheme 7, path a) [57]. Tri-, di-, and monofluoroalkylated derivatives were also obtained by using fluoroalkyl heteroaryl sulfones [58] or sodium sulfinates (in the presence of persulfate) [59] as the alkylating agents. In an alternative
- lamp (280–780 nm), in a photocatalyst-free fashion [61]. Easily scalable and thermally stable arylthiodifluoromethyl 2-pyridyl sulfones were likewise exploited in the visible-light photocatalyzed arylthiodifluoromethylation of differently substituted isocyanides [62]. 6-Arylphenanthridines were
Graphical Abstract
Figure 1: Bioactive phenanthridine and phenanthridinium derivatives.
Scheme 1: Synthesis of phenanthrenes by a photo-Pschorr reaction.
Scheme 2: Synthesis of phenanthrenes by a benzannulation reaction.
Scheme 3: Photocatalytic cyclization of α-bromochalcones for the synthesis of phenanthrenes.
Figure 2: Carbon-centered and nitrogen-centered radicals used for the synthesis of phenanthridines.
Scheme 4: General scheme describing the synthesis of phenanthridines from isocyanides via imidoyl radicals.
Scheme 5: Synthesis of substituted phenanthridines involving the intermediacy of electrophilic radicals.
Scheme 6: Photocatalyzed synthesis of 6-β-ketoalkyl phenanthridines.
Scheme 7: Synthesis of 6-substituted phenanthridines through the addition of trifluoromethyl (path a), phenyl...
Scheme 8: Synthesis of 6-(trifluoromethyl)-7,8-dihydrobenzo[k]phenanthridine.
Scheme 9: Phenanthridine syntheses by using photogenerated radicals formed through a C–H bond homolytic cleav...
Scheme 10: Trifluoroacetimidoyl chlorides as starting substrates for the synthesis of 6-(trifluoromethyl)phena...
Scheme 11: Synthesis of phenanthridines via aryl–aryl-bond formation.
Scheme 12: Oxidative conversion of N-biarylglycine esters to phenanthridine-6-carboxylates.
Scheme 13: Photocatalytic synthesis of benzo[f]quinolines from 2-heteroaryl-substituted anilines and heteroary...
Scheme 14: Synthesis of noravicine (14.2a) and nornitidine (14.2b) alkaloids.
Scheme 15: Gram-scale synthesis of the alkaloid trisphaeridine (15.3).
Scheme 16: Synthesis of phenanthridines starting from vinyl azides.
Scheme 17: Synthesis of pyrido[4,3,2-gh]phenanthridines 17.5a–d through the radical trifluoromethylthiolation ...
Scheme 18: The direct oxidative C–H amidation involving amidyl radicals for the synthesis of phenanthridones.
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
- example, based on N-containing heterocycles (isoxazolones, pyrazolones, pyrazolidin-3,5-diones, and 1,2,3-triazolones [52]), sulfones [65], and phosphonates [54] (Scheme 8). Based on the data of EPR spectroscopy [35][38][49][50][66] and quantum chemical calculations [67], the maximum spin density in
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.
Photocatalysis with organic dyes: facile access to reactive intermediates for synthesis
- Stephanie G. E. Amos,
- Marion Garreau,
- Luca Buzzetti and
- Jerome Waser
Beilstein J. Org. Chem. 2020, 16, 1163–1187, doi:10.3762/bjoc.16.103
- reaction (Scheme 23) [100]. The alkynes 23.1 could be successfully converted to the vinyl sulfones 23.3 in the presence of the aryl sulfones 23.2 using eosin Y (OD13) as a photocatalyst. A tentative mechanism was proposed by the authors: under visible-light irradiation, the arylsulfinic acid could be
- desired vinyl sulfones. C–X radical anions and derived neutral radicals Amidst charged radical species, ketyl radicals play a central role in organic synthesis (Figure 3). As intermediates, they are more stable because the charge is mainly localized on the oxygen atom. They are postulated to be the
Graphical Abstract
Figure 1: Selected examples of organic dyes. Mes-Acr+: 9-mesityl-10-methylacridinium, DCA: 9,10-dicyanoanthra...
Scheme 1: Activation modes in photocatalysis.
Scheme 2: Main strategies for the formation of C(sp3) radicals used in organophotocatalysis.
Scheme 3: Illustrative example for the photocatalytic oxidative generation of radicals from carboxylic acids:...
Scheme 4: Illustrative example for the photocatalytic reductive generation of C(sp3) radicals from redoxactiv...
Figure 2: Common substrates for the photocatalytic oxidative generation of C(sp3) radicals.
Scheme 5: Illustrative example for the photocatalytic oxidative generation of radicals from dihydropyridines ...
Scheme 6: Illustrative example for the photocatalytic oxidative generation of C(sp3) radicals from trifluorob...
Scheme 7: Illustrative example for the photocatalytic reductive generation of C(sp3) radicals from benzylic h...
Scheme 8: Illustrative example for the photocatalytic generation of C(sp3) radicals via direct HAT: the cross...
Scheme 9: Illustrative example for the photocatalytic generation of C(sp3) radicals via indirect HAT: the deu...
Scheme 10: Selected precursors for the generation of aryl radicals using organophotocatalysis.
Scheme 11: Illustrative example for the photocatalytic reductive generation of aryl radicals from aryl diazoni...
Scheme 12: Illustrative examples for the photocatalytic reductive generation of aryl radicals from haloarenes:...
Scheme 13: Illustrative example for the photocatalytic reductive generation of aryl radicals from aryl halides...
Scheme 14: Illustrative example for the photocatalytic reductive generation of aryl radicals from arylsulfonyl...
Scheme 15: Illustrative example for the reductive photocatalytic generation of aryl radicals from triaryl sulf...
Scheme 16: Main strategies towards acyl radicals used in organophotocatalysis.
Scheme 17: Illustrative example for the decarboxylative photocatalytic generation of acyl radicals from α-keto...
Scheme 18: Illustrative example for the oxidative photocatalytic generation of acyl radicals from acyl silanes...
Scheme 19: Illustrative example for the oxidative photocatalytic generation of carbamoyl radicals from 4-carba...
Scheme 20: Illustrative example of the photocatalytic HAT approach for the generation of acyl radicals from al...
Scheme 21: General reactivity of a) radical cations; b) radical anions; c) the main strategies towards aryl an...
Scheme 22: Illustrative example for the oxidative photocatalytic generation of alkene radical cations from alk...
Scheme 23: Illustrative example for the reductive photocatalytic generation of an alkene radical anion from al...
Figure 3: Structure of C–X radical anions and their neutral derivatives.
Scheme 24: Illustrative example for the photocatalytic reduction of imines and the generation of an α-amino C(...
Scheme 25: Illustrative example for the oxidative photocatalytic generation of aryl radical cations from arene...
Scheme 26: NCR classifications and generation.
Scheme 27: Illustrative example for the photocatalytic reductive generation of iminyl radicals from O-aryl oxi...
Scheme 28: Illustrative example for the photocatalytic oxidative generation of iminyl radicals from α-N-oxy ac...
Scheme 29: Illustrative example for the photocatalytic oxidative generation of iminyl radicals via an N–H bond...
Scheme 30: Illustrative example for the photocatalytic oxidative generation of amidyl radicals from Weinreb am...
Scheme 31: Illustrative example for the photocatalytic reductive generation of amidyl radicals from hydroxylam...
Scheme 32: Illustrative example for the photocatalytic reductive generation of amidyl radicals from N-aminopyr...
Scheme 33: Illustrative example for the photocatalytic oxidative generation of amidyl radicals from α-amido-ox...
Scheme 34: Illustrative example for the photocatalytic oxidative generation of aminium radicals: the N-aryltet...
Scheme 35: Illustrative example for the photocatalytic oxidative generation of nitrogen-centered radical catio...
Scheme 36: Illustrative example for the photocatalytic oxidative generation of nitrogen-centered radical catio...
Scheme 37: Illustrative example for the photocatalytic oxidative generation of hydrazonyl radical from hydrazo...
Scheme 38: Generation of O-radicals.
Scheme 39: Illustrative examples for the photocatalytic generation of O-radicals from N-alkoxypyridinium salts...
Scheme 40: Illustrative examples for the photocatalytic generation of O-radicals from alkyl hydroperoxides: th...
Scheme 41: Illustrative example for the oxidative photocatalytic generation of thiyl radicals from thiols: the...
Scheme 42: Main strategies and reagents for the generation of sulfonyl radicals used in organophotocatalysis.
Scheme 43: Illustrative example for the reductive photocatalytic generation of sulfonyl radicals from arylsulf...
Scheme 44: Illustrative example of a Cl atom abstraction strategy for the photocatalytic generation of sulfamo...
Scheme 45: Illustrative example for the oxidative photocatalytic generation of sulfonyl radicals from sulfinic...
Scheme 46: Illustrative example for the photocatalytic generation of electronically excited triplet states: th...
Scheme 47: Illustrative example for the photocatalytic generation of electronically excited triplet states: th...
Accelerating fragment-based library generation by coupling high-performance photoreactors with benchtop analysis
- Quentin Lefebvre,
- Christophe Salomé and
- Thomas C. Fessard
Beilstein J. Org. Chem. 2020, 16, 982–988, doi:10.3762/bjoc.16.87
- of complex amines: bicyclopentanamines, azetidines, spiroazetidines, spiropyrrolidines and spiropiperidines. Functional group tolerance was probed by using functionalized building blocks bearing esters, carbamates, alcohols, tertiary amines, ethers, sulfones and fluorine atoms (Scheme 2 and Scheme 3
Graphical Abstract
Scheme 1: One-day workflow for fragment-based library generation. QC: Quality control. MPLC: Medium-pressure ...
Figure 1: Top: high-power blue LED photoreactors. Bottom, from left to right: photoreactor OFF, ON, and ON th...
Figure 2: TLC–MS equipment: analysis of 5 reactions in 5 minutes.
Figure 3: Pre-QC validation by 60 MHz benchtop NMR.
Scheme 2: Scope of the fragment-based library generation: BCP-amines and azetidines. See Supporting Information File 1 for experimental de...
Scheme 3: Scope of the fragment-based library generation: pyrrolidines, piperidines and morpholines. See Supporting Information File 1 for...
Aldehydes as powerful initiators for photochemical transformations
- Maria A. Theodoropoulou,
- Nikolaos F. Nikitas and
- Christoforos G. Kokotos
Beilstein J. Org. Chem. 2020, 16, 833–857, doi:10.3762/bjoc.16.76
- radical reenters the catalytic cycle. Various alkyl substituents on the cyclobutene ring, such as substituents bearing a chlorine atom, or silyl ethers were well-tolerated. However, bulky groups (e.g., TBDMS) led to lower yields. Methyl, ethyl, or aryl sulfones were all compatible with this methodology
Graphical Abstract
Scheme 1: Norrish type I and II dissociations.
Scheme 2: Proposed radical pair formation after the photolysis of benzaldehyde (8).
Scheme 3: Aldehydes in the Paterno–Büchi reaction.
Scheme 4: 2,3-Diazabicyclo[2.2.1]hept-2-ene (DBH).
Scheme 5: Dissociation pathways of benzaldehyde.
Scheme 6: Reactions that lead to polarized products detectable by CIDNP.
Scheme 7: MMA (26), DEABP (27), and Michler’s ketone (28).
Scheme 8: Radical intermediates of DEABP.
Scheme 9: Photoinitiated polymerization of monomeric MMA (26) using the quinoxalines 32 and benzaldehyde (8).
Scheme 10: Acetone (4) and formaldehyde (35) as photografting initiators.
Scheme 11: Photografting by employing acetaldehyde (36) as the photoinitiator.
Scheme 12: Proposed photolysis mechanism for aliphatic ketones 44 and formaldehyde (35).
Scheme 13: Initiator 50, reductant 51, and benzaldehyde derivatives 52–54 for the polymerization of the methac...
Scheme 14: Proposed mechanism of the photomediated atom transfer radical polymerization employing the benzalde...
Scheme 15: cis/trans isomerization employing triplet states of photosensitizers.
Scheme 16: Salicylaldehyde (68) forms an internal hydrogen bond.
Scheme 17: Olefin isomerization via energy transfer from a carbonyl compound.
Scheme 18: Mechanistic pathways for the Paterno–Büchi reaction.
Scheme 19: Isomeric oxetanes formed after photochemical addition of aryl aldehydes to 2-butenes.
Scheme 20: Rotation of the C3–C4 bond of the biradical intermediate may lead to all four conformations.
Scheme 21: Photolysis products of benzaldehyde (8) in different solvents. a) In benzene or ethanol. b) In hex-...
Scheme 22: N-tert-Butylbenzamide formation proceeds via a benzoyl radical.
Scheme 23: Photochemical pinacol coupling.
Scheme 24: Photochemical ATRA catalyzed by 4-anisaldehyde (52).
Scheme 25: Proposed triplet sensitization mechanism of the ATRA reaction in the presence of 4-anisaldehyde (52...
Scheme 26: Benzaldehyde-mediated photoredox CDC reaction: compatible amides and ethers.
Scheme 27: Photoredox cross-dehydrogenative coupling (CDC) conditions and proposed reaction mechanism.
Scheme 28: Optimized conditions for the photoredox merger reaction.
Scheme 29: Proposed mechanism for the C(sp3)–H alkylation/arylation of ethers.
Scheme 30: Substrate scope for the photochemical alkylation of ethers.
Scheme 31: C(sp3)–H Functionalization of N-containing molecules.
Scheme 32: Substrate scope for the photochemical alkylation of N-containing molecules.
Scheme 33: Additional products yielded by the photochemical alkylation reaction of N-containing molecules.
Scheme 34: C(sp3)–H functionalization of thioethers.
Scheme 35: Proposed mechanism for the C(sp3)–H alkylation/arylation of N-containing molecules and thioethers.
Scheme 36: Hydroacylation using 4-cyanobenzaldehyde (53) as the photoinitiator.
Scheme 37: Selectivity for the formation of the α,α-disubstituted aldehydes.
Scheme 38: Substrate scope for the photochemical addition of aldehydes to Michael acceptors.
Scheme 39: Proposed mechanism for the hydroacylation of Michael acceptors using 4-cyanobenzaldehyde (53) as th...
Scheme 40: Catalytic arylation of aromatic aldehydes by aryl bromides in which the reaction product acts as th...
Scheme 41: Proposed mechanism for the catalytic arylation of benzaldehydes by aryl bromides in which the react...
Scheme 42: Functionalization of the chiral cyclobutanes 180.
Scheme 43: Optimized reaction conditions and proposed mechanism for the sulfonylcyanation of cyclobutenes.
Recent advances in Cu-catalyzed C(sp3)–Si and C(sp3)–B bond formation
- Balaram S. Takale,
- Ruchita R. Thakore,
- Elham Etemadi-Davan and
- Bruce H. Lipshutz
Beilstein J. Org. Chem. 2020, 16, 691–737, doi:10.3762/bjoc.16.67
- decade later, Molander et al. made use of the same disilane as a source of the nucleophile for additions to α,β-unsaturated alkenes and alkynes as Michael acceptors bearing sulfones, nitriles, cyano, amido, and carboxyl ester groups to form β-silylated alkanes and alkenes in good to moderate yields [55
Graphical Abstract
Scheme 1: Pharmaceuticals possessing a silicon or boron atom.
Scheme 2: The first Cu-catalyzed C(sp3)–Si bond formation.
Scheme 3: Conversion of benzylic phosphate 6 to the corresponding silane.
Scheme 4: Conversion of alkyl triflates to alkylsilanes.
Scheme 5: Conversion of secondary alkyl triflates to alkylsilanes.
Scheme 6: Conversion of alkyl iodides to alkylsilanes.
Scheme 7: Trapping of intermediate radical through cascade reaction.
Scheme 8: Radical pathway for conversion of alkyl iodides to alkylsilanes.
Scheme 9: Conversion of alkyl ester of N-hydroxyphthalimide to alkylsilanes.
Scheme 10: Conversion of gem-dibromides to bis-silylalkanes.
Scheme 11: Conversion of imines to α-silylated amines (A) and the reaction pathway (B).
Scheme 12: Conversion of N-tosylimines to α-silylated amines.
Scheme 13: Screening of diamine ligands.
Scheme 14: Conversion of N-tert-butylsulfonylimines to α-silylated amines.
Scheme 15: Conversion of aldimines to nonracemic α-silylated amines.
Scheme 16: Conversion of N-tosylimines to α-silylated amines.
Scheme 17: Reaction pathway [A] and conversion of aldehydes to α-silylated alcohols [B].
Scheme 18: Conversion of aldehydes to benzhydryl silyl ethers.
Scheme 19: Conversion of ketones to 1,2-diols (A) and conversion of imines to 1,2-amino alcohols (B).
Scheme 20: Ligand screening (A) and conversion of aldehydes to α-silylated alcohols (B).
Scheme 21: Conversion of aldehydes to α-silylated alcohols.
Scheme 22: 1,4-Additions to α,β-unsaturated ketones.
Scheme 23: 1,4-Additions to unsaturated ketones to give β-silylated derivatives.
Scheme 24: Additions onto α,β-unsaturated lactones to give β-silylated lactones.
Scheme 25: Conversion of α,β-unsaturated to β-silylated lactams.
Scheme 26: Conversion of N-arylacrylamides to silylated oxindoles.
Scheme 27: Conversion of α,β-unsaturated carbonyl compounds to silylated tert-butylperoxides.
Scheme 28: Catalytic cycle for Cu(I) catalyzed α,β-unsaturated compounds.
Scheme 29: Conversion of p-quinone methides to benzylic silanes.
Scheme 30: Conversion of α,β-unsaturated ketimines to regio- and stereocontrolled allylic silanes.
Scheme 31: Conversion of α,β-unsaturated ketimines to enantioenriched allylic silanes.
Scheme 32: Regioselective conversion of dienedioates to allylic silanes.
Scheme 33: Conversion of alkenyl-substituted azaarenes to β-silylated adducts.
Scheme 34: Conversion of conjugated benzoxazoles to enantioenriched β-silylated adducts.
Scheme 35: Conversion of α,β-unsaturated carbonyl indoles to α-silylated N-alkylated indoles.
Scheme 36: Conversion of β-amidoacrylates to α-aminosilanes.
Scheme 37: Conversion of α,β-unsaturated ketones to enantioenriched β-silylated ketones, nitriles, and nitro d...
Scheme 38: Regio-divergent silacarboxylation of allenes.
Scheme 39: Silylation of diazocarbonyl compounds, (A) asymmetric and (B) racemic.
Scheme 40: Enantioselective hydrosilylation of alkenes.
Scheme 41: Conversion of 3-acylindoles to indolino-silanes.
Scheme 42: Proposed mechanism for the silylation of 3-acylindoles.
Scheme 43: Silyation of N-chlorosulfonamides.
Scheme 44: Conversion of acyl silanes to α-silyl alcohols.
Scheme 45: Conversion of N-tosylaziridines to β-silylated N-tosylamines.
Scheme 46: Conversion of N-tosylaziridines to silylated N-tosylamines.
Scheme 47: Conversion of 3,3-disubstituted cyclopropenes to silylated cyclopropanes.
Scheme 48: Conversion of conjugated enynes to 1,3-bis(silyl)propenes.
Scheme 49: Proposed sequence for the Cu-catalyzed borylation of substituted alkenes.
Scheme 50: Cu-catalyzed synthesis of nonracemic allylic boronates.
Scheme 51: Cu–NHC catalyzed synthesis of α-substituted allylboronates.
Scheme 52: Synthesis of α-chiral (γ-alkoxyallyl)boronates.
Scheme 53: Cu-mediated formation of nonracemic cis- or trans- 2-substituted cyclopropylboronates.
Scheme 54: Cu-catalyzed synthesis of γ,γ-gem-difluoroallylboronates.
Scheme 55: Cu-catalyzed hydrofunctionalization of internal alkenes and vinylarenes.
Scheme 56: Cu-catalyzed Markovnikov and anti-Markovnikov borylation of alkenes.
Scheme 57: Cu-catalyzed borylation/ortho-cyanation/Cope rearrangement.
Scheme 58: Borylfluoromethylation of alkenes.
Scheme 59: Cu-catalyzed synthesis of tertiary nonracemic alcohols.
Scheme 60: Synthesis of densely functionalized and synthetically versatile 1,2- or 4,3-borocyanated 1,3-butadi...
Scheme 61: Cu-catalyzed trifunctionalization of allenes.
Scheme 62: Cu-catalyzed selective arylborylation of arenes.
Scheme 63: Asymmetric borylative coupling between styrenes and imines.
Scheme 64: Regio-divergent aminoboration of unactivated terminal alkenes.
Scheme 65: Cu-catalyzed 1,4-borylation of α,β-unsaturated ketones.
Scheme 66: Cu-catalyzed protodeboronation of α,β-unsaturated ketones.
Scheme 67: Cu-catalyzed β-borylation of α,β-unsaturated imines.
Scheme 68: Cu-catalyzed synthesis of β-trifluoroborato carbonyl compounds.
Scheme 69: Asymmetric 1,4-borylation of α,β-unsaturated carbonyl compounds.
Scheme 70: Cu-catalyzed ACB and ACA reactions of α,β-unsaturated 2-acyl-N-methylimidazoles.
Scheme 71: Cu-catalyzed diborylation of aldehydes.
Scheme 72: Umpolung pathway for chiral, nonracemic tertiary alcohol synthesis (top) and proposed mechanism for...
Scheme 73: Cu-catalyzed synthesis of α-hydroxyboronates.
Scheme 74: Cu-catalyzed borylation of ketones.
Scheme 75: Cu-catalyzed borylation of unactivated alkyl halides.
Scheme 76: Cu-catalyzed borylation of allylic difluorides.
Scheme 77: Cu-catalyzed borylation of cyclic and acyclic alkyl halides.
Scheme 78: Cu-catalyzed borylation of unactivated alkyl chlorides and bromides.
Scheme 79: Cu-catalyzed decarboxylative borylation of carboxylic acids.
Scheme 80: Cu-catalyzed borylation of benzylic, allylic, and propargylic alcohols.
Recent advances in photocatalyzed reactions using well-defined copper(I) complexes
- Mingbing Zhong,
- Xavier Pannecoucke,
- Philippe Jubault and
- Thomas Poisson
Beilstein J. Org. Chem. 2020, 16, 451–481, doi:10.3762/bjoc.16.42
- chlorides [20]. This ATRA reaction was carried out with various fluoroalkylsulfonyl chlorides, such as CFH2SO2Cl, CF2HSO2Cl, CF3SO2Cl, CF3CH2SO2Cl, and C4F9SO2Cl, electron-deficient alkenes, including α,β-unsaturated ketones, amides, esters, carboxylic acids, sulfones, and phosphonates (Scheme 4). In
- ) [25]. This copper-catalyzed photocatalytic reduction generated an aryl radical that was trapped with various allylating reagents. First, the phenyl radical generated from the corresponding diphenyliodonium salt was added to various allyl sulfones substituted in the 2-position. The products were
Graphical Abstract
Scheme 1: [Cu(I)(dap)2]Cl-catalyzed ATRA reaction under green light irradiation.
Scheme 2: Photocatalytic allylation of α-haloketones.
Scheme 3: [Cu(I)(dap)2]Cl-photocatalyzed chlorosulfonylation and chlorotrifluoromethylation of alkenes.
Scheme 4: Photocatalytic perfluoroalkylchlorination of electron-deficient alkenes using the Sauvage catalyst.
Scheme 5: Photocatalytic synthesis of fluorinated sultones.
Scheme 6: Photocatalyzed haloperfluoroalkylation of alkenes and alkynes.
Scheme 7: Chlorosulfonylation of alkenes catalyzed by [Cu(I)(dap)2]Cl. aNo Na2CO3 was added. b1 equiv of Na2CO...
Scheme 8: Copper-photocatalyzed reductive allylation of diaryliodonium salts.
Scheme 9: Copper-photocatalyzed azidomethoxylation of olefins.
Scheme 10: Benzylic azidation initiated by [Cu(I)(dap)2]Cl.
Scheme 11: Trifluoromethyl methoxylation of styryl derivatives using [Cu(I)(dap)2]PF6. All redox potentials ar...
Scheme 12: Trifluoromethylation of silyl enol ethers.
Scheme 13: Synthesis of annulated heterocycles upon oxidation with the Sauvage catalyst.
Scheme 14: Oxoazidation of styrene derivatives using [Cu(dap)2]Cl as a precatalyst.
Scheme 15: [Cu(I)(dpp)(binc)]PF6-catalyzed ATRA reaction.
Scheme 16: Allylation reaction of α-bromomalonate catalyzed by [Cu(I)(dpp)(binc)]PF6 following an ATRA mechani...
Scheme 17: Bromo/tribromomethylation reaction using [Cu(I)(dmp)(BINAP)]PF6.
Scheme 18: Chlorotrifluoromethylation of alkenes catalyzed by [Cu(I)(N^N)(xantphos)]PF6.
Scheme 19: Chlorosulfonylation of styrene and alkyne derivatives by ATRA reactions.
Scheme 20: Reduction of aryl and alkyl halides with the complex [Cu(I)(bcp)(DPEPhos)]PF6. aIrradiation was car...
Scheme 21: Meerwein arylation of electron-rich aromatic derivatives and 5-exo-trig cyclization catalyzed by th...
Scheme 22: [Cu(I)(bcp)(DPEPhos)]PF6-photocatalyzed synthesis of alkaloids. aYield over two steps (cyclization ...
Scheme 23: Copper-photocatalyzed decarboxylative amination of NHP esters.
Scheme 24: Photocatalytic decarboxylative alkynylation using [Cu(I)(dq)(binap)]BF4.
Scheme 25: Copper-photocatalyzed alkylation of glycine esters.
Scheme 26: Copper-photocatalyzed borylation of organic halides. aUnder continuous flow conditions.
Scheme 27: Copper-photocatalyzed α-functionalization of alcohols with glycine ester derivatives.
Scheme 28: δ-Functionalization of alcohols using [Cu(I)(dmp)(xantphos)]BF4.
Scheme 29: Photocatalytic synthesis of [5]helicene and phenanthrene.
Scheme 30: Oxidative carbazole synthesis using in situ-formed [Cu(I)(dmp)(xantphos)]BF4.
Scheme 31: Copper-photocatalyzed functionalization of N-aryl tetrahydroisoquinolines.
Scheme 32: Bicyclic lactone synthesis using a copper-photocatalyzed PCET reaction.
Scheme 33: Photocatalytic Pinacol coupling reaction catalyzed by [Cu(I)(pypzs)(BINAP)]BF4. The ligands of the ...
Scheme 34: Azide photosensitization using a Cu-based photocatalyst.
Copper-catalyzed enantioselective conjugate addition of organometallic reagents to challenging Michael acceptors
- Delphine Pichon,
- Jennifer Morvan,
- Christophe Crévisy and
- Marc Mauduit
Beilstein J. Org. Chem. 2020, 16, 212–232, doi:10.3762/bjoc.16.24
- , and Grignard reagents to Michael acceptors. In that respect, since the pioneering example reported by Alexakis and co-workers in 1993 [5], a wide range of cyclic and acyclic electron-deficient alkenes, such as α,β-unsaturated ketones, esters, nitriles, sulfones, or nitroolefines, was intensively
- vinyl sulfones as electrophiles (Scheme 3). Of note, both the anti- and the syn-product could be predominantly formed (with a anti:syn ratio from 83:17 to 15:85), and no diastereocontrol occurred in the absence of the organocatalyst. Interestingly, this simple protocol was successfully applied to the
Graphical Abstract
Scheme 1: Competitive side reactions in the Cu ECA of organometallic reagents to α,β-unsaturated aldehydes.
Scheme 2: Cu-catalyzed ECA of α,β-unsaturated aldehydes with phosphoramidite- (a) and phosphine-based ligands...
Scheme 3: One-pot Cu-catalyzed ECA/organocatalyzed α-substitution of enals.
Scheme 4: Combination of copper and amino catalysis for enantioselective β-functionalizations of enals.
Scheme 5: Optimized conditions for the Cu ECAs of R2Zn, RMgBr, and AlMe3 with α,β-unsaturated aldehydes.
Scheme 6: CuECA of Grignard reagents to α,β-unsaturated thioesters and their application in the asymmetric to...
Scheme 7: Improved Cu ECA of Grignard reagents to α,β-unsaturated thioesters, and their application in the as...
Scheme 8: Catalytic enantioselective synthesis of vicinal dialkyl arrays via Cu ECA of Grignard reagents to γ...
Scheme 9: 1,6-Cu ECA of MeMgBr to α,β,γ,δ-bisunsaturated thioesters: an iterative approach to deoxypropionate...
Scheme 10: Tandem Cu ECA/intramolecular enolate trapping involving 4-chloro-α,β-unsaturated thioester 22.
Scheme 11: Cu ECA of Grignard reagents to 3-boronyl α,β-unsaturated thioesters.
Scheme 12: Cu ECA of alkylzirconium reagents to α,β-unsaturated thioesters.
Scheme 13: Conversion of acylimidazoles into aldehydes, ketones, acids, esters, amides, and amines.
Scheme 14: Cu ECA of dimethyl malonate to α,β-unsaturated acylimidazole 31 with triazacyclophane-based ligand ...
Scheme 15: Cu/L13-catalyzed ECA of alkylboranes to α,β-unsaturated acylimidazoles.
Scheme 16: Cu/hydroxyalkyl-NHC-catalyzed ECA of dimethylzinc to α,β-unsaturated acylimidazoles.
Scheme 17: Stereocontrolled synthesis of 3,5,7-all-syn and anti,anti-stereotriads via iterative Cu ECAs.
Scheme 18: Stereocontrolled synthesis of anti,syn- and anti,anti-3,5,7-(Me,OR,Me) units via iterative Cu ECA/B...
Scheme 19: Cu-catalyzed ECA of dialkylzinc reagents to α,β-unsaturated N-acyloxazolidinones.
Scheme 20: Cu/phosphoramidite L16-catalyzed ECA of dialkylzincs to α,β-unsaturated N-acyl-2-pyrrolidinones.
Scheme 21: Cu/(R,S)-Josiphos (L9)-catalyzed ECA of Grignard reagents to α,β-unsaturated amides.
Scheme 22: Cu/Josiphos (L9)-catalyzed ECA of Grignard reagents to polyunsaturated amides.
Scheme 23: Cu-catalyzed ECA of trimethylaluminium to N-acylpyrrole derivatives.
Fluorine-containing substituents: metabolism of the α,α-difluoroethyl thioether motif
- Andrea Rodil,
- Alexandra M. Z. Slawin,
- Nawaf Al-Maharik,
- Ren Tomita and
- David O’Hagan
Beilstein J. Org. Chem. 2019, 15, 1441–1447, doi:10.3762/bjoc.15.144
- compounds that are of commercial significance [8][9][10]. Metabolism studies in both of these cases show that the major metabolites are their corresponding sulfoxides (Ar–S(O)CF3) and sulfones (Ar–S(O)2CF3) [8][9]. Indeed, in the case of the insecticide fipronil it is actually the sulfoxide (Ar–S(O)CF3
- very active and outcompetes demethylation, however, that demethylation is significantly more active that the second oxidation of sulfoxides to sulfones. Incubation of naphthalene 5 with C. elegans, generated three new metabolites 11–13 which arose by oxidations at sulphur and hydroxylations of the
- analysed by 1H and 19F NMR before further purification by HPLC. Purification of the fluorometabolites The fluorometabolites (sulfoxides and sulfones) were isolated by reversed-phase HPLC using a Shimadzu Prominence (SIL-20A HT autosampler, CL-20AT ternary pump, DGU-20A3R solvent degasser, SPD 20A UV
Graphical Abstract
Figure 1: Structures of trifluoromethyl sulfonyl ether bioactives.
Figure 2: Comparison of log P values of comparative aryl thioether motifs [18].
Figure 3: α,α-Difluoroethyl thioether substrates for metabolism studies.
Scheme 1: Fluorometabolites 6–8 isolated after incubation of 4 with C. elegans. Ratios are the average of thr...
Scheme 2: Putative pathways for (α,α-difluoroethyl)(4-methoxyphenyl)sulfane (4) metabolism.
Scheme 3: C. elegans incubation of 5. Ratios are the average of three incubations.
Scheme 4: Incubation (four times) of oxygen ether 14 with C. elegans, gave 4-acetoxyphenol (15) as the major ...
Synthesis of non-racemic 4-nitro-2-sulfonylbutan-1-ones via Ni(II)-catalyzed asymmetric Michael reaction of β-ketosulfones
- Alexander N. Reznikov,
- Anastasiya E. Sibiryakova,
- Marat R. Baimuratov,
- Eugene V. Golovin,
- Victor B. Rybakov and
- Yuri N. Klimochkin
Beilstein J. Org. Chem. 2019, 15, 1289–1297, doi:10.3762/bjoc.15.127
- University, Leninskie Gory, 1, 119991, Mosсow, Russian Federation 10.3762/bjoc.15.127 Abstract Functionally substituted sulfones with stereogenic centers are valuable reagents in organic synthesis and key motifs in some bioactive compounds. The asymmetric Michael addition of β-ketosulfones to conjugated
- ; Michael addition; nickel complexes; nitroalkenes; Introduction Sulfones are widely used in organic synthesis, particularly, in various reactions of C–C and C=C-bond formation [1][2][3][4]. The use of sulfones in Julia–Kocienski [1] and Ramberg–Bäcklund reactions [2] made this class of compounds
- cytotoxicity [9]. However, it is of great importance to obtain all stereoisomers for the study of biological activity. Therefore, the development of methods for the asymmetric synthesis of polyfunctional sulfones is valuable. The most notable of them are Ag- and Cu-catalyzed 1,3-dipolar cycloaddition reactions
Graphical Abstract
Figure 1: Рharmacologically active sulfones.
Figure 2: Structures of the ligands L1–L8.
Figure 3: Evolution of the conversion of 5 and diastereomeric composition of the products of reaction of 5a w...
Figure 4: Time profile of epimerization and retro-Michael reaction of (2R,3S)-8a in chloroform-d solution.
Figure 5: ORTEP diagram of (2R,3S)-8d.
Scheme 1: The proposed mechanism of asymmetric addition of β-ketosulfones to nitroalkenes.
Scheme 2: Transition state models for asymmetric addition of β-ketosulfones to nitroalkenes.
Synthesis of aryl cyclopropyl sulfides through copper-promoted S-cyclopropylation of thiophenols using cyclopropylboronic acid
- Emeline Benoit,
- Ahmed Fnaiche and
- Alexandre Gagnon
Beilstein J. Org. Chem. 2019, 15, 1162–1171, doi:10.3762/bjoc.15.113
- forms. For example, aryl cyclopropyl sulfones have been used in the preparation of glucokinase (GK) activators for the treatment of type 2 diabetes [1][2][3][4][5] while aryl cyclopropyl sulfoximines have been utilized for the synthesis of modulators of glucokinase regulatory protein (GKRP) [6][7][8
Graphical Abstract
Scheme 1: Synthetic uses of aryl cyclopropyl sulfides 1.
Scheme 2: Synthesis of aryl cyclopropyl sulfides.
Scheme 3: Substrate scope in the copper-promoted S-cyclopropylation of thiophenols 14 using cyclopropylboroni...
Scheme 4: Copper-catalyzed S-cyclopropylation of 4-tert-butylbenzenethiol (14a) using potassium cyclopropyl t...
Electrophilic oligodeoxynucleotide synthesis using dM-Dmoc for amino protection
- Shahien Shahsavari,
- Dhananjani N. A. M. Eriyagama,
- Bhaskar Halami,
- Vagarshak Begoyan,
- Marina Tanasova,
- Jinsen Chen and
- Shiyue Fang
Beilstein J. Org. Chem. 2019, 15, 1116–1128, doi:10.3762/bjoc.15.108
- ]. The dithioketal groups in the dM-Dmoc and Dmoc functions of 32 were then oxidized with a solution of sodium periodate at room temperature to give 33. The 5'-trityl tag survived the conditions. It should be pointed out that some sulfoxides might be further oxidized to sulfones, which should not affect
Graphical Abstract
Scheme 1: Comparison of Dmoc and dM-Dmoc as nucleobase protecting groups for ODN synthesis.
Figure 1: dM-Dmoc phosphoramidite monomers and CPG with Dmoc linker.
Scheme 2: Synthesis of compound 5 [44], nucleoside phosphoramidite monomers 3a–c and phosphoramidite capping agen...
Figure 2: Structure of phosphoramidites containing electrophilic groups.
Scheme 3: Synthesis of ester-containing phosphoramidite 26a.
Figure 3: ODN sequences 30a–e. Their 5'-tritylated versions are labeled as 30a-tr, 30b-tr, 30c-tr, 30d-tr, an...
Figure 4: RP HPLC profiles of (a) crude 30a-tr, (b) pure 30a-tr, (c) crude 30a, (d) pure 30a, (e) crude 30c-tr...
Figure 5: PAGE analyses of ODNs 30a–e. Lanes 1–5 are ODNs 30a–e, respectively.
Figure 6: MALDI–TOF MS of (a) ODN 30a and (b) 30c.
Scheme 4: ODN deprotection and cleavage under non-nucleophilic conditions.
Oxidative radical ring-opening/cyclization of cyclopropane derivatives
- Yu Liu,
- Qiao-Lin Wang,
- Zan Chen,
- Cong-Shan Zhou,
- Bi-Quan Xiong,
- Pan-Liang Zhang,
- Chang-An Yang and
- Quan Zhou
Beilstein J. Org. Chem. 2019, 15, 256–278, doi:10.3762/bjoc.15.23
- sulfonylation of teriary cyclopropanols 91 with sodium sulfinates 129 for the synthesis of γ-keto sulfones 130 in excellent yields (Scheme 34) [114]. The reaction was compatible with a series of fluoroalkyl, aryl and alkyl sulfinate salts. Notably, oxygen instead of THBP as oxidation was viable in this
Graphical Abstract
Scheme 1: The oxidative radical ring-opening/cyclization of cyclopropane derivatives.
Scheme 2: Mn(OAc)3-mediated oxidative radical ring-opening and cyclization of MCPs with malonates.
Scheme 3: Mn(III)-mediated oxidative radical ring-opening and cyclization of MCPs with 1,3-dicarbonyl compoun...
Scheme 4: Heat-promoted ring-opening/cyclization of MCPs with elemental chalgogens.
Scheme 5: Copper(II) acetate-mediated oxidative radical ring-opening and cyclization of MCPs with diphenyl di...
Scheme 6: AIBN-promoted oxidative radical ring-opening and cyclization of MCPs with benzenethiol.
Scheme 7: AIBN-mediated oxidative radical ring-opening and cyclization of MCPs with diethyl phosphites.
Scheme 8: Organic-selenium induced radical ring-opening and cyclization of MCPs derivatives (cyclopropylaldeh...
Scheme 9: Copper(I)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs with To...
Scheme 10: Ag(I)-mediated trifluoromethylthiolation/ring-opening/cyclization of MCPs with AgSCF3.
Scheme 11: oxidative radical ring-opening and cyclization of MCPs with α-C(sp3)-–H of ethers.
Scheme 12: Oxidative radical ring-opening and cyclization of MCPs with aldehydes.
Scheme 13: Cu(I) or Fe(II)-catalyzed oxidative radical trifluoromethylation/ring-opening/cyclization of MCPs d...
Scheme 14: Rh(II)-catalyzed oxidative radical ring-opening and cyclization of MCPs.
Scheme 15: Ag(I)-catalyzed oxidative radical amination/ring-opening/cyclization of MCPs derivatives.
Scheme 16: Heating-promoted radical ring-opening and cyclization of MCP derivatives (arylvinylidenecyclopropan...
Scheme 17: Bromine radical-mediated ring-opening of alkylidenecyclopropanes.
Scheme 18: Fluoroalkyl (Rf) radical-mediated ring-opening of MCPs.
Scheme 19: Visible-light-induced alkylation/ring-opening/cyclization of cyclopropyl olefins with bromides.
Scheme 20: Mn(III)-mediated ring-opening and [3 + 3]-annulation of cyclopropanols and vinyl azides.
Scheme 21: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with quinones.
Scheme 22: Ag(I)-catalyzed oxidative ring-opening of cyclopropanols with heteroarenes.
Scheme 23: Cu(I)-catalyzed oxidative ring-opening/trifluoromethylation of cyclopropanols.
Scheme 24: Cu(I)-catalyzed oxidative ring-opening and trifluoromethylation/trifluoromethylthiolation of cyclop...
Scheme 25: Ag(I)-mediated oxidative ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 26: Photocatalyzed ring-opening/fluorination of cyclopropanols with Selectfluor.
Scheme 27: Na2S2O8-promoted ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 28: Ag(I)-catalyzed ring-opening and chlorination of cyclopropanols with aldehydes.
Scheme 29: Ag(I)-catalyzed ring-opening/alkynylation of cyclopropanols with EBX.
Scheme 30: Na2S2O8-promoted ring-opening/alkylation of cyclopropanols with acrylamides.
Scheme 31: Cyclopropanol ring-opening initiated tandem cyclization with acrylamides or 2-isocyanobiphenyls.
Scheme 32: Ag(II)-mediated oxidative ring-opening/fluorination of cyclopropanols with AgF2.
Scheme 33: Cu(II)-catalyzed ring-opening/fluoromethylation of cyclopropanols with sulfinate salts.
Scheme 34: Cu(II)-catalyzed ring-opening/sulfonylation of cyclopropanols with sulfinate salts.
Scheme 35: Na2S2O8-promoted ring-opening/arylation of cyclopropanols with propiolamides.
Scheme 36: The ring-opening and [3 + 2]-annulation of cyclopropanols with α,β-unsaturated aldehydes.
Scheme 37: Cu(II)-catalyzed ring-opening/arylation of cyclopropanols with aromatic nitrogen heterocyles.
Scheme 38: Ag(I)-catalyzed ring-opening and difluoromethylthiolation of cyclopropanols with PhSO2SCF2H.
Scheme 39: Ag(I)-catalyzed ring-opening and acylation of cyclopropanols with aldehydes.
Scheme 40: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of 2-oxyranyl ketones.
Scheme 41: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of linear enones.
Scheme 42: Aerobic oxidation ring-opening of cyclopropanols for the synthesis of metabolite.
Cross metathesis-mediated synthesis of hydroxamic acid derivatives
- Shital Kumar Chattopadhyay,
- Subhankar Ghosh and
- Suman Sil
Beilstein J. Org. Chem. 2018, 14, 3070–3075, doi:10.3762/bjoc.14.285
- CM-mediated synthesis of functionalized alkenes of various kinds continue to appear. For example, cross metathesis with acrylates [8][9][10], α,ß-unsaturated acid chlorides [11], acrylamides [12][13][14], vinyl sulfones [15], vinylphosphine oxides [16], vinyl phosphonates [17], enones [18], and
Graphical Abstract
Figure 1: Some bioactive molecules containing hydroxamate functionality.
Scheme 1: Cross metathesis between a class-I alkene and N-benzyloxyacryl amide.
Applications of organocatalysed visible-light photoredox reactions for medicinal chemistry
- Michael K. Bogdos,
- Emmanuel Pinard and
- John A. Murphy
Beilstein J. Org. Chem. 2018, 14, 2035–2064, doi:10.3762/bjoc.14.179
- chemistry. The formation of the thioether is also quite interesting, due to the possibility of accessing sulfones, which are abundant in drugs and drug-like molecules. The scope of the reaction covers the basics in terms of substituents on both reactants and investigates various substitution patterns. Most
- the modified substituted imidazo[1,2-a]pyridines contains scaffolds commonly found in pharmaceuticals, such as sulfones 9a and trifluoromethyl groups 9b. Hence, this publication provides an easy route to access scaffolds with diverse aromatic systems, allowing for the construction of interesting
Graphical Abstract
Figure 1: Depiction of the energy levels of a typical organic molecule and the photophysical processes it can...
Figure 2: General catalytic cycle of a photocatalyst in a photoredox organocatalysed reaction. [cat] – photoc...
Figure 3: Structures and names of the most common photocatalysts encountered in the reviewed literature.
Figure 4: General example of a reductive quenching catalytic cycle. [cat] – photocatalyst, [cat]* – photocata...
Figure 5: General example of an oxidative quenching catalytic cycle. [cat] – photocatalyst, [cat]* – photocat...
Scheme 1: Oxidative coupling of aldehydes and amines to amides using acridinium salt photocatalysis.
Figure 6: Biologically active molecules containing a benzamide linkage.
Scheme 2: The photocatalytic reduction of amino acids to produce the corresponding free or protected amines.
Scheme 3: The organocatalysed photoredox base-mediated oxidation of thiols to disulfides.
Scheme 4: C-Terminal modification of peptides and proteins using organophotoredox catalysis.
Scheme 5: The reduction and aryl coupling of aryl halides using a doubly excited photocatalyst (PDI).
Figure 7: Mechanism for the coupling of aryl halides using PDI, which is excited sequentially by two photons.
Scheme 6: The arylation of five-membered heteroarenes using arenediazonium salts under organophotoredox condi...
Scheme 7: The C–H (hetero)arylation of five-membered heterocycles under Eosin Y photocatalysis.
Scheme 8: The C–H sulfurisation of imidazoheterocycles using Eosin B-catalyzed photochemical methods.
Scheme 9: The introduction of the thiocyanate group using Eosin Y photocatalysis.
Scheme 10: Sulfonamidation of pyrroles using oxygen as the terminal oxidant.
Scheme 11: DDQ-catalysed C–H amination of arenes and heteroarenes.
Scheme 12: Photoredox-promoted radical Michael addition reactions of allylic or benzylic carbons.
Figure 8: Proposed mechanistic rationale for the observed chemoselectivities.
Scheme 13: The photocatalytic manipulation of C–H bonds adjacent to amine groups.
Scheme 14: The perylene-catalysed organophotoredox tandem difluoromethylation–acetamidation of styrene-type al...
Figure 9: Examples of biologically active molecules containing highly functionalised five membered heterocycl...
Scheme 15: The [3 + 2]-cycloaddition leading to the formation of pyrroles, through the reaction of 2H-azirines...
Figure 10: Proposed intermediate that determines the regioselectivity of the reaction.
Figure 11: Comparison of possible pathways of reaction and various intermediates involved.
Scheme 16: The acridinium salt-catalysed formation of oxazoles from aldehydes and 2H-azirines.
Scheme 17: The synthesis of oxazolines and thiazolines from amides and thioamides using organocatalysed photor...
Figure 12: Biologically active molecules on the market containing 1,3,4-oxadiazole moieties.
Scheme 18: The synthesis of 1,3,4-oxadiazoles from aldehyde semicarbazones using Eosin Y organophotocatalysis.
Scheme 19: The dimerization of primary thioamides to 1,2,4-thiadiazoles catalysed by the presence of Eosin Y a...
Scheme 20: The radical cycloaddition of o-methylthioarenediazonium salts and substituted alkynes towards the f...
Scheme 21: The dehydrogenative cascade reaction for the synthesis of 5,6-benzofused heterocyclic systems.
Figure 13: Trifluoromethylated version of compounds which have known biological activities.
Scheme 22: Eosin Y-catalysed photoredox formation of 3-substituted benzimidazoles.
Scheme 23: Oxidation of dihydropyrimidines by atmospheric oxygen using photoredox catalysis.
Scheme 24: Photoredox-organocatalysed transformation of 2-substituted phenolic imines to benzoxazoles.
Scheme 25: Visible light-driven oxidative annulation of arylamidines.
Scheme 26: Methylene blue-photocatalysed direct C–H trifluoromethylation of heterocycles.
Scheme 27: Photoredox hydrotrifluoromethylation of terminal alkenes and alkynes.
Scheme 28: Trifluoromethylation and perfluoroalkylation of aromatics and heteroaromatics.
Scheme 29: The cooperative asymmetric and photoredox catalysis towards the functionalisation of α-amino sp3 C–...
Scheme 30: Organophotoredox-catalysed direct C–H amidation of aromatics.
Scheme 31: Direct C–H alkylation of heterocycles using BF3K salts. CFL – compact fluorescent lamp.
Figure 14: The modification of camptothecin, demonstrating the use of the Molander protocol in LSF.
Scheme 32: Direct C–H amination of aromatics using acridinium salts.
Scheme 33: Photoredox-catalysed nucleophilic aromatic substitution of nucleophiles onto methoxybenzene derivat...
Scheme 34: The direct C–H cyanation of aromatics with a focus on its use for LSF.
Hypervalent organoiodine compounds: from reagents to valuable building blocks in synthesis
- Gwendal Grelier,
- Benjamin Darses and
- Philippe Dauban
Beilstein J. Org. Chem. 2018, 14, 1508–1528, doi:10.3762/bjoc.14.128
- . The same group has then developed a radical method to access the corresponding sulfones from cyclic diaryl-λ3-iodanes (Scheme 33) [73]. The reaction is catalyzed by a 1,10-phenanthroline-copper complex and affords the dibenzothiophene-5,5-dioxides 76 in moderate to high yields. The transformation has
Graphical Abstract
Scheme 1: Strategies to address the issue of sustainability with polyvalent organoiodine reagents.
Scheme 2: Functionalization of ketones and alkenes with IBX.
Scheme 3: Functionalization of pyrroles with DMP.
Scheme 4: Catalytic benzoyloxy-trifluoromethylation reported by Szabó.
Scheme 5: Catalytic benzoyloxy-trifluoromethylation reported by Mideoka.
Scheme 6: Catalytic 1,4-benzoyloxy-trifluoromethylation of dienes.
Scheme 7: Catalytic benzoyloxy-trifluoromethylation of allylamines.
Scheme 8: Catalytic benzoyloxy-trifluoromethylation of enynes.
Scheme 9: Catalytic benzoyloxy-trifluoromethylation of allenes.
Scheme 10: Alkynylation of N-(aryl)imines with EBX for the formation of furans.
Scheme 11: Catalytic benzoyloxy-alkynylation of diazo compounds.
Scheme 12: Catalytic asymmetric benzoyloxy-alkynylation of diazo compounds.
Scheme 13: Catalytic 1,2-benzoyloxy-azidation of alkenes.
Scheme 14: Catalytic 1,2-benzoyloxy-azidation of enamides.
Scheme 15: Catalytic 1,2-benzoyloxy-iodination of alkenes.
Scheme 16: Seminal study with cyclic diaryl-λ3-iodane.
Scheme 17: Synthesis of alkylidenefluorenes from cyclic diaryl-λ3-iodanes.
Scheme 18: Synthesis of alkyne-substituted alkylidenefluorenes.
Scheme 19: Synthesis of phenanthrenes from cyclic diaryl-λ3-iodanes.
Scheme 20: Synthesis of dibenzocarbazoles from cyclic diaryl-λ3-iodanes.
Scheme 21: Synthesis of triazolophenantridines from cyclic diaryl-λ3-iodanes.
Scheme 22: Synthesis of functionalized benzoxazoles from cyclic diaryl-λ3-iodanes.
Scheme 23: Sequential difunctionalization of cyclic diaryl-λ3-iodanes.
Scheme 24: Double Suzuki–Miyaura coupling reaction of cyclic diaryl-λ3-iodanes.
Scheme 25: Synthesis of a δ-carboline from cyclic diaryl-λ3-iodane.
Scheme 26: Synthesis of N-(aryl)carbazoles from cyclic diaryl-λ3-iodanes.
Scheme 27: Synthesis of carbazoles from cyclic diaryl-λ3-iodanes.
Scheme 28: Synthesis of carbazoles and acridines from cyclic diaryl-λ3-iodanes.
Scheme 29: Synthesis of dibenzothiophenes from cyclic diaryl-λ3-iodanes.
Scheme 30: Synthesis of various sulfur heterocycles from cyclic diaryl-λ3-iodanes.
Scheme 31: Synthesis of dibenzothioheterocycles from cyclic diaryl-λ3-iodanes.
Scheme 32: Synthesis of dibenzosulfides and dibenzoselenides from cyclic diaryl-λ3-iodanes.
Scheme 33: Synthesis of dibenzosulfones from cyclic diaryl-λ3-iodanes.
Scheme 34: Seminal study with linear diaryl-λ3-iodanes.
Scheme 35: N-Arylation of benzotriazole with symmetrical diaryl-λ3-iodanes.
Scheme 36: Tandem catalytic C–H/N–H arylation of indoles with diaryl-λ3-iodanes.
Scheme 37: Tandem N-arylation/C(sp2)–H arylation with diaryl-λ3-iodanes.
Scheme 38: Catalytic intermolecular diarylation of anilines with diaryl-λ3-iodanes.
Scheme 39: Catalytic synthesis of diarylsulfides with diaryl-λ3-iodanes.
Scheme 40: α-Arylation of enolates using [bis(trifluoroacetoxy)iodo]arenes.
Scheme 41: Mechanism of the α-arylation using [bis(trifluoroacetoxy)iodo]arene.
Scheme 42: Catalytic nitrene additions mediated by [bis(acyloxy)iodo]arenes.
Scheme 43: Tandem of C(sp3)–H amination/sila-Sonogashira–Hagihara coupling.
Scheme 44: Tandem reaction using a λ3-iodane as an oxidant, a substrate and a coupling partner.
Scheme 45: Synthesis of 1,2-diarylated acrylamidines with ArI(OAc)2.
Photocatalytic formation of carbon–sulfur bonds
- Alexander Wimmer and
- Burkhard König
Beilstein J. Org. Chem. 2018, 14, 54–83, doi:10.3762/bjoc.14.4
- . General concepts, synthetic strategies and the substrate scope of reactions yielding thiols, disulfides, sulfoxides, sulfones and other organosulfur compounds are discussed together with the proposed mechanistic pathways. Keywords: disulfides; photocatalysis; sulfones; sulfoxides; thiols; visible light
- of allyl and vinyl sulfones In 2015, our laboratory reported the first metal-free visible-light photoredox-catalyzed method for the preparation of vinyl sulfones from the respective aryl sulfinate salts (Scheme 42a) [77]. Eosin Y was applied as photocatalyst to produce a diverse scope of vinyl
- sulfones. For styrene derivatives, the solvent had to be changed from ethanol to a mixture of DMF/H2O as the nucleophile ethanol leads to a byproduct formation. The reaction proceeds via oxidative quenching of the photoexcited state of Eosin Y by nitrobenzene to generate the Eosin Y radical cation. In
Graphical Abstract
Scheme 1: General overview over the sulfur-based substrates and reactive intermediates that are discussed in ...
Scheme 2: Photoredox-catalyzed radical thiol–ene reaction, applying [Ru(bpz)3](PF6)2 as photocatalyst.
Scheme 3: Photoredox-catalyzed thiol–ene reaction of aliphatic thiols with alkenes enabled by aniline derivat...
Scheme 4: Photoredox-catalyzed radical thiol–ene reaction for the postfunctionalization of polymers (a) and n...
Scheme 5: Photoredox-catalyzed thiol–ene reaction enabled by bromotrichloromethane as redox additive.
Scheme 6: Photoredox-catalyzed preparation of β-ketosulfoxides with Eosin Y as organic dye as photoredox cata...
Scheme 7: Greaney’s photocatalytic radical thiol–ene reaction, applying TiO2 nanoparticles as photocatalyst.
Scheme 8: Fadeyi’s photocatalytic radical thiol–ene reaction, applying Bi2O3 as photocatalyst.
Scheme 9: Ananikov’s photocatalytic radical thiol-yne reaction, applying Eosin Y as photocatalyst.
Scheme 10: Organocatalytic visible-light photoinitiated thiol–ene coupling, applying phenylglyoxylic acid as o...
Scheme 11: Xia’s photoredox-catalyzed synthesis of 2,3-disubstituted benzothiophenes, applying 9-mesityl-10-me...
Scheme 12: Wang’s metal-free photoredox-catalyzed radical thiol–ene reaction, applying 9-mesityl-10-methylacri...
Scheme 13: Visible-light benzophenone-catalyzed metal- and oxidant-free radical thiol–ene reaction.
Scheme 14: Visible-light catalyzed C-3 sulfenylation of indole derivatives using Rose Bengal as organic dye.
Scheme 15: Photocatalyzed radical thiol–ene reaction and subsequent aerobic sulfide-oxidation with Rose Bengal...
Scheme 16: Photoredox-catalyzed synthesis of diaryl sulfides.
Scheme 17: Photocatalytic cross-coupling of aryl thiols with aryl diazonium salts, using Eosin Y as photoredox...
Scheme 18: Photocatalyzed cross-coupling of aryl diazonium salts with cysteines in batch and in a microphotore...
Scheme 19: Fu’s [Ir]-catalyzed photoredox arylation of aryl thiols with aryl halides.
Scheme 20: Fu’s photoredox-catalyzed difluoromethylation of aryl thiols.
Scheme 21: C–S cross-coupling of thiols with aryl iodides via [Ir]-photoredox and [Ni]-dual-catalysis.
Scheme 22: C–S cross-coupling of thiols with aryl bromides, applying 3,7-bis-(biphenyl-4-yl)-10-(1-naphthyl)ph...
Scheme 23: Collin’s photochemical dual-catalytic cross-coupling of thiols with bromoalkynes.
Scheme 24: Visible-light-promoted C–S cross-coupling via intermolecular electron donor–acceptor complex format...
Scheme 25: Li’s visible-light photoredox-catalyzed thiocyanation of indole derivatives with Rose Bengal as pho...
Scheme 26: Hajra’s visible-light photoredox-catalyzed thiocyanation of imidazoheterocycles with Eosin Y as pho...
Scheme 27: Wang’s photoredox-catalyzed thiocyanation reaction of indoles, applying heterogeneous TiO2/MoS2 nan...
Scheme 28: Yadav’s photoredox-catalyzed α-C(sp3)–H thiocyanation reaction for tertiary amines, applying Eosin ...
Scheme 29: Yadav’s photoredox-catalyzed synthesis of 5-aryl-2-imino-1,3-oxathiolanes.
Scheme 30: Yadav’s photoredox-catalyzed synthesis of 1,3-oxathiolane-2-thiones.
Scheme 31: Li’s photoredox catalysis for the preparation of 2-substituted benzothiazoles, applying [Ru(bpy)3](...
Scheme 32: Lei’s external oxidant-free synthesis of 2-substituted benzothiazoles by merging photoredox and tra...
Scheme 33: Metal-free photocatalyzed synthesis of 2-aminobenzothiazoles, applying Eosin Y as photocatalyst.
Scheme 34: Metal-free photocatalyzed synthesis of 1,3,4-thiadiazoles, using Eosin Y as photocatalyst.
Scheme 35: Visible-light photoredox-catalyzed preparation of benzothiophenes with Eosin Y.
Scheme 36: Visible-light-induced KOH/DMSO superbase-promoted preparation of benzothiophenes.
Scheme 37: Jacobi von Wangelin’s photocatalytic approach for the synthesis of aryl sulfides, applying Eosin Y ...
Scheme 38: Visible-light photosensitized α-C(sp3)–H thiolation of aliphatic ethers.
Scheme 39: Visible-light photocatalyzed cross-coupling of alkyl and aryl thiosulfates with aryl diazonium salt...
Scheme 40: Visible-light photocatalyzed, controllable sulfenylation and sulfoxidation with organic thiosulfate...
Scheme 41: Rastogi’s photoredox-catalyzed methylsulfoxidation of aryl diazonium salts, using [Ru(bpy)3]Cl2 as ...
Scheme 42: a) Visible-light metal-free Eosin Y-catalyzed procedure for the preparation of vinyl sulfones from ...
Scheme 43: Visible-light photocatalyzed cross-coupling of sodium sulfinates with secondary enamides.
Scheme 44: Wang’s photocatalyzed oxidative cyclization of phenyl propiolates with sulfinic acids, applying Eos...
Scheme 45: Lei’s sacrificial oxidant-free synthesis of allyl sulfones by merging photoredox and transition met...
Scheme 46: Photocatalyzed Markovnikov-selective radical/radical cross-coupling of aryl sulfinic acids and term...
Scheme 47: Visible-light Eosin Y induced cross-coupling of aryl sulfinic acids and styrene derivatives, afford...
Scheme 48: Photoredox-catalyzed bicyclization of 1,7-enynes with sulfinic acids, applying Eosin Y as photocata...
Scheme 49: Visible-light-accelerated C–H-sulfinylation of arenes and heteroarenes.
Scheme 50: Visible-light photoredox-catalyzed β-selenosulfonylation of electron-rich olefins, applying [Ru(bpy)...
Scheme 51: Photocatalyzed preparation of β-chlorosulfones from the respective olefins and p-toluenesulfonyl ch...
Scheme 52: a) Photocatalyzed preparation of β-amidovinyl sulfones from sulfonyl chlorides. b) Preparation of β...
Scheme 53: Visible-light photocatalyzed sulfonylation of aliphatic tertiary amines, applying [Ru(bpy)3](PF6)2 ...
Scheme 54: Reiser’s visible-light photoredox-catalyzed preparation of β-hydroxysulfones from sulfonyl chloride...
Scheme 55: a) Sun’s visible-light-catalyzed approach for the preparation of isoquinolinonediones, applying [fac...
Scheme 56: Visible-light photocatalyzed sulfonylation/cyclization of vinyl azides, applying [Ru(bpy)3]Cl2 as p...
Scheme 57: Visible-light photocatalyzed procedure for the formation of β-ketosulfones from aryl sulfonyl chlor...
Scheme 58: Zheng’s method for the sulfenylation of indole derivatives, applying sulfonyl chlorides via visible...
Scheme 59: Cai’s visible-light induced synthesis of β-ketosulfones from sulfonyl hydrazines and alkynes.
Scheme 60: Photoredox-catalyzed approach for the preparation of vinyl sulfones from sulfonyl hydrazines and ci...
Scheme 61: Jacobi von Wangelin’s visible-light photocatalyzed chlorosulfonylation of anilines.
Scheme 62: Three-component photoredox-catalyzed synthesis of N-amino sulfonamides, applying PDI as organic dye....
Scheme 63: Visible-light induced preparation of complex sulfones from oximes, silyl enol ethers and SO2.
Electrophilic trifluoromethylselenolation of terminal alkynes with Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate
- Clément Ghiazza,
- Anis Tlili and
- Thierry Billard
Beilstein J. Org. Chem. 2017, 13, 2626–2630, doi:10.3762/bjoc.13.260
- the nucleophilic addition of Se-(trifluoromethyl) 4-methylbenzenesulfonoselenoate, a stable and easy-to-handle reagent, to alkynes is described. This reaction provides trifluoromethylselenylated vinyl sulfones with good results and the method was extended also to higher fluorinated homologs. The
- -methylbenzenesulfonoselenoate and Se-(perfluoroalkyl) 4-methylbenzenesulfonoselenoate have been confirmed as valuable bench-stable reagents to perform perfluoroalkylselenolations. Nucleophilic additions with alkynes to provide perfluoroalkylselenolated vinyl sulfones can easily be carried out. Se-(Trifluoromethyl) 4
Graphical Abstract
Scheme 1: Electrophilic addition of 1a to alkynes. Yields shown are those of isolated products; yields determ...
Figure 1: Single-crystal X-ray structure of 3a.
Scheme 2: Mechanism proposal.
Scheme 3: Perfluoroalkylselenolation of alkynes. Yields shown are those of isolated products; yields determin...
Conjugated nitrosoalkenes as Michael acceptors in carbon–carbon bond forming reactions: a review and perspective
- Yaroslav D. Boyko,
- Valentin S. Dorokhov,
- Alexey Yu. Sukhorukov and
- Sema L. Ioffe
Beilstein J. Org. Chem. 2017, 13, 2214–2234, doi:10.3762/bjoc.13.220
- reported the use of β-ketoxime sulfones 61 in the reaction with lithium acetylides that resulted in formal substitution of the sulfinate group through an elimination–addition mechanism (Scheme 21) [43]. Interestingly, unlike α-halooximes, 1,4-elimination in sulfones 61 to generate nitrosoalkenes NSA13
- (+/−)-perhydrohistrionicotoxin. Addition of Gilman’s reagents to α,β-epoxy oximes 53. Addition of Gilman’s reagents to α-chlorooximes. Reaction of silyl nitronate 58 with organolithium reagents via nitrosoalkene NSA12. Reaction of β-ketoxime sulfones 61 and 63 with lithium acetylides. Electrophilic addition of nitrosoalkenes
Graphical Abstract
Scheme 1: Precursors of nitrosoalkenes NSA.
Scheme 2: Reactions of cyclic α-chlorooximes 1 with 1,3-dicarbonyl compounds.
Scheme 3: C-C-coupling of N,N-bis(silyloxy)enamines 3 with 1,3-dicarbonyl compounds.
Scheme 4: Reaction of N,N-bis(silyloxy)enamines 3 with nitronate anions.
Scheme 5: Reaction of α-chlorooximes TBS ethers 2 with ester enolates.
Scheme 6: Assembly of bicyclooctanone 14 via an intramolecular cyclization of nitrosoalkene NSA2.
Scheme 7: A general strategy for the assembly of bicyclo[2.2.1]heptanes via an intramolecular cyclization of ...
Scheme 8: Stereochemistry of Michael addition to cyclic nitrosoalkene NSA3.
Scheme 9: Stereochemistry of Michael addition to acyclic nitrosoalkenes NSA4.
Scheme 10: Stereochemistry of Michael addition to γ-alkoxy nitrosoalkene NSA5.
Scheme 11: Oppolzer’s total synthesis of 3-methoxy-9β-estra(1,3,5(10))trien(11,17)dione (25).
Scheme 12: Oppolzer’s total synthesis of (+/−)-isocomene.
Figure 1: Alkaloids synthesized using stereoselective Michael addition to conjugated nitrosoalkenes.
Scheme 13: Weinreb’s total synthesis of alstilobanines A, E and angustilodine.
Scheme 14: Weinreb’s approach to the core structure of apparicine alkaloids.
Scheme 15: Weinreb’s synthesis of (+/−)-myrioneurinol via stereoselective conjugate addition of malonate to ni...
Scheme 16: Reactions of cyclic α-chloro oximes with Grignard reagents.
Scheme 17: Corey’s synthesis of (+/−)-perhydrohistrionicotoxin.
Scheme 18: Addition of Gilman’s reagents to α,β-epoxy oximes 53.
Scheme 19: Addition of Gilman’s reagents to α-chlorooximes.
Scheme 20: Reaction of silyl nitronate 58 with organolithium reagents via nitrosoalkene NSA12.
Scheme 21: Reaction of β-ketoxime sulfones 61 and 63 with lithium acetylides.
Scheme 22: Electrophilic addition of nitrosoalkenes NSA14 to electron-rich arenes.
Scheme 23: Addition of nitrosoalkenes NSA14 to pyrroles and indoles.
Scheme 24: Reaction of phosphinyl nitrosoalkenes NSA15 with indole.
Scheme 25: Reaction of pyrrole with α,α’-dihalooximes 70.
Scheme 26: Synthesis of indole-derived psammaplin A analogue 72.
Scheme 27: Synthesis of tryptophanes by reduction of oximinoalkylated indoles 68.
Scheme 28: Ottenheijm’s synthesis of neoechinulin B analogue 77.
Scheme 29: Synthesis of 1,2-dihydropyrrolizinones 82 via addition of pyrrole to ethyl bromopyruvate oxime.
Scheme 30: Kozikowski’s strategy to indolactam-based alkaloids via addition of indoles to ethyl bromopyruvate ...
Scheme 31: Addition of cyanide anion to nitrosoalkenes and subsequent cyclization to 5-aminoisoxazoles 86.
Scheme 32: Et3N-catalysed addition of trimethylsilyl cyanide to N,N-bis(silyloxy)enamines 3 leading to 5-amino...
Scheme 33: Addition of TMSCN to allenyl N-siloxysulfonamide 89.
Scheme 34: Reaction of nitrosoallenes NSA16 with malodinitrile and ethyl cyanoacetic ester.
Scheme 35: [4 + 1]-Annulation of nitrosoalkenes NSA with sulfonium ylides 92.
Scheme 36: Reaction of diazo compounds 96 with nitrosoalkenes NSA.
Scheme 37: Tandem Michael addition/oxidative cyclization strategy to isoxazolines 100.
1-Imidoalkylphosphonium salts with modulated Cα–P+ bond strength: synthesis and application as new active α-imidoalkylating agents
- Jakub Adamek,
- Roman Mazurkiewicz,
- Anna Węgrzyk and
- Karol Erfurt
Beilstein J. Org. Chem. 2017, 13, 1446–1455, doi:10.3762/bjoc.13.142
- difficult and elaborate. Most of these, including the most frequently used α-alkoxy derivatives (Z = OR), N-[1-(benzotriazol-1-yl)alkyl]amides (Z = 1-benzotriazolyl) and 1-(N-acylamino)alkyl sulfones (Z = SO2Ar) require activation with Lewis acids, which are expensive (e.g., ZrCl4, VCl3, CeCl3, Bi(OTf)3 or
Graphical Abstract
Scheme 1: α-Amidoalkylation reactions under basic or acidic conditions.
Scheme 2: Synthetic routes of α-amido- and α-imidoalkylation of aromatic and heteroaromatic compounds.
Scheme 3: Reaction of imidophosphonium salt 5e with 1,3,5-trimethoxybenzene.
Synthesis of alkynyl-substituted camphor derivatives and their use in the preparation of paclitaxel-related compounds
- M. Fernanda N. N. Carvalho,
- Rudolf Herrmann and
- Gabriele Wagner
Beilstein J. Org. Chem. 2017, 13, 1230–1238, doi:10.3762/bjoc.13.122
- supported by the IR spectrum. Only one S=O vibration can be identified at 1098 cm−1, in a similar position as the S=O vibrations in DMSO (1050 cm−1) or tert-butylsulfinamide (1032 cm−1) [43]. The strong band at about 1330 cm−1, typical for the asymmetric S=O stretch in sulfonamides and sulfones, is absent
Graphical Abstract
Scheme 1: Synthesis of 3-oxo-camphorsulfonylimine (3) [13,15] and its bis-alkynyl derivatives 4 from camphor-10-sulf...
Scheme 2: Reactions of bis-alkynyl camphor derivative 4a with TiCl4 and with Br2, respectively.
Scheme 3: Reactions of bis-alkynylcamphor derivatives 4a–e with catalytic amounts of PtCl2(PhCN)2.
Scheme 4: Attempted selective synthesis of 3-alkynyl derivatives via sulfonylimine reduction of oxoimide 3.
Scheme 5: Selective synthesis of 2-alkynyl derivatives by protection of the 3-oxo group as an acetal.
Scheme 6: Selective synthesis of 2-alkynyl derivatives by protection of the 3-oxo group as an imine.
Scheme 7: Synthesis of the bis-alkynyl derivatives bearing different alkyne substituents and their platinum-c...
Scheme 8: Proposed mechanism of the platinum-catalysed cycloisomerisation.
Urea–hydrogen peroxide prompted the selective and controlled oxidation of thioglycosides into sulfoxides and sulfones
- Adesh Kumar Singh,
- Varsha Tiwari,
- Kunj Bihari Mishra,
- Surabhi Gupta and
- Jeyakumar Kandasamy
Beilstein J. Org. Chem. 2017, 13, 1139–1144, doi:10.3762/bjoc.13.113
- thioglycosides to corresponding glycosyl sulfoxides and sulfones is reported using urea–hydrogen peroxide (UHP). A wide range of glycosyl sulfoxides are selectively achieved using 1.5 equiv of UHP at 60 °C while corresponding sulfones are achieved using 2.5 equiv of UHP at 80 °C in acetic acid. Remarkably
- , oxidation susceptible olefin functional groups were found to be stable during the oxidation of sulfide. Keywords: monosaccharides; oxidation; sulfones; sulfoxides; thioglycosides; urea–hydrogen peroxide; Introduction Organosulfur compounds such as sulfides, sulfoxides and sulfones are useful intermediates
- role in carbohydrate synthesis. Thioglycosides, glycosyl sulfoxides and sulfones have been widely used as glycosyl donors in oligosaccharide synthesis which can be activated under mild reaction conditions [5][6][7][8][9][10]. Glycosyl sulfoxide donors usually provide excellent anomeric selectivity
Ultrasound-promoted organocatalytic enamine–azide [3 + 2] cycloaddition reactions for the synthesis of ((arylselanyl)phenyl-1H-1,2,3-triazol-4-yl)ketones
- Gabriel P. Costa,
- Natália Seus,
- Juliano A. Roehrs,
- Raquel G. Jacob,
- Ricardo F. Schumacher,
- Thiago Barcellos,
- Rafael Luque and
- Diego Alves
Beilstein J. Org. Chem. 2017, 13, 694–702, doi:10.3762/bjoc.13.68
- 1,2,3-triazoles [33][34][35][36][37]. Selanyltriazoyl carboxylates, carboxamides, carbonitriles or sulfones were synthesized in good to excellent yields using catalytic amounts of an organocatalyst. Organoselenium compounds are attractive synthetic targets because of their selective reactions [38][39
Graphical Abstract
Figure 1: Biologically relevant selanyl-1,2,3-triazoles.
Scheme 1: General scheme of the reaction.
Scheme 2: Comparative study of the conventional conditions and ultrasound irradiation. Conditions A: Reaction...
Scheme 3: Reaction of 2-azidophenyl phenyl selenide 1a with activated ketones 2f–k.
1H-Imidazol-4(5H)-ones and thiazol-4(5H)-ones as emerging pronucleophiles in asymmetric catalysis
- Antonia Mielgo and
- Claudio Palomo
Beilstein J. Org. Chem. 2016, 12, 918–936, doi:10.3762/bjoc.12.90
- the pionnering work by Trost in 2004 [26], several examples of the utility of the structurally related oxazol-4(5H)-ones (Figure 1b, X = O) have also been published, which involve mainly Michael additions (to enones [27][28], nitroalkenes [29][30], alkynones [31][32][33] and vinyl sulfones [34]), γ
Graphical Abstract
Figure 1: Some α-substituted heterocycles for asymmetric catalysis, their reactivity patterns against enoliza...
Figure 2: 1H-Imidazol-4(5H)-ones 1 and thiazol-4(5H)-ones 2.
Scheme 1: a) Synthesis of 2-thio-1H-imidazol-4(5H)-ones [55] and b) preparation of the starting thiohydantoins [59].
Scheme 2: Selected examples of the Michael addition of 2-thio-1H-imidazol-4(5H)-ones to nitroalkenes [55]. aReact...
Scheme 3: Michael addition of thiohydantoins to nitrostyrene assisted by Et3N and catalysts C1 and C3. aAbsol...
Scheme 4: Elaboration of the Michael adducts coming from the Michael addition to nitroalkenes [55].
Figure 3: Proposed model for the Michael addition of 1H-imidazol4-(5H)-ones and selected 1H NMR data which su...
Scheme 5: Michael addition 2-thio-1H-imidazol-4(5H)-ones to the α-silyloxyenone 29 [55].
Scheme 6: Elaboration of the Michael adducts coming from the Michael addition to nitroolefins [55].
Scheme 7: Rhodanines in asymmetric catalytic reactions: a) Reaction with rhodanines of type 44 [78-80]; b) reactions...
Scheme 8: Michael addition of thiazol-4(5H)-ones to nitroolefins promoted by the ureidopeptide-like bifunctio...
Figure 4: Ureidopeptide-like Brønsted bases: catalyst design. a) Previous known design. b) Proposed new desig...
Scheme 9: Ureidopeptide-like Brønsted base bifunctional catalyst preparation. NMM = N-methylmorpholine, THF =...
Scheme 10: Selected examples of the Michael addition of thiazolones to different nitroolefins promoted by cata...
Scheme 11: Elaboration of the Michael adducts to α,α-disubstituted α-mercaptocarboxylic acid derivatives [85].
Scheme 12: Effect of the nitrogen atom at the aromatic substituent of the thiazolone on yield and stereoselect...
Scheme 13: Michael addition reaction of thiazol-4(5H)ones 74 to α’-silyloxyenone 29 [73].
Scheme 14: Elaboration of the thiazolone Michael adducts [73].
Scheme 15: Enantioselective γ-addition of oxazol-4(5H)-ones and thiazol-4(5H)-ones to allenoates promoted by C6...
Scheme 16: Enantioselective γ-addition of thiazol-4(5H)-ones and oxazol-4(5H)-ones to alkynoate 83 promoted by ...
Scheme 17: Proposed mechanism for the C6-catalyzed γ-addition of thiazol-4(5H)-one to allenoates. Adapted from ...
Scheme 18: Catalytic enantioselective α-amination of thiazolones promoted by ureidopeptide like catalysts C5 a...
Scheme 19: Iridium-catalized asymmetric allyllation of substituted oxazol-4(5H)-ones and thiazol-4(5H)-ones pr...
