The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of ar...The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of aromatic nucleophillic substitution and has potential value in synthesis to obtain (-substituted naphthalene derivaties.展开更多
The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied. α-Alkylation with alkyl halides was favoured, whereas γ-selection was achieved in the reaction with aldehydes.
Summary of main observation and conclusion Direct functionalization of alkenes and direct transformation of carboxamides are two exciting areas that have attracted considerable attention in recent years.We report here...Summary of main observation and conclusion Direct functionalization of alkenes and direct transformation of carboxamides are two exciting areas that have attracted considerable attention in recent years.We report herein that secondary amides,the least reactive derivatives of carbonyl compounds,upon activated with triflic anhydride,can serve as effective hydroacylating reagents in partner with alkenes to yield ketones at ambient temperature.The method was applied to the one-step synthesis of racemic dihydro-ar-turmerone.In this method,alkenes serve as surrogates of organometallic reagents,which allows the orthogonal chemoselective reactions.The ready availability of many olefins such as camphene and norbornene permits one-step ketone synthesis that would require several steps by conventional methods.展开更多
In recent years,exciting progress has been made in the field of direct transformation of amides,nevertheless,the condensation between two amides remains rare and restricted to homo-coupling reactions.Herein,we report ...In recent years,exciting progress has been made in the field of direct transformation of amides,nevertheless,the condensation between two amides remains rare and restricted to homo-coupling reactions.Herein,we report the cross-coupling of secondary amides with tertiary amides,which provides a synthesis of ketones under mild conditions,and features the use of tertiary amides as surrogates of alkyl carbanions.The method relies on the coupling of enamines,generated from tertiary amides by catalytic partial reduction of tertiary amides with Vaska's catalyst,with nitrilium ions,formed in situ from secondary amides via activation with trifluoromethanesulfonic anhydride,and on the subsequent deformylation.展开更多
The (S)-sulfide 6 has been synthesized as a synthetic equivalent of novel 3-piperidinol N-α-carbanion B via deprotonation and lithium naphthanelide (LN)-mediated reductive lithiation. The reaction of the 3-piperidino...The (S)-sulfide 6 has been synthesized as a synthetic equivalent of novel 3-piperidinol N-α-carbanion B via deprotonation and lithium naphthanelide (LN)-mediated reductive lithiation. The reaction of the 3-piperidinol N-α-carbanion intermediate B with carbonyl compounds gave, besides some reduced product 2a, the desired α-hydroxyalkylation products 12-17 with excellent 2,3-diastereoselectivity. The reductive α-hydroxyalkylation with unsymmetric carbonyl compounds led to only 50:50 to 77:23 diastereoselectivities at the C-1' carbinol center.展开更多
Wereport a base-promoted catalyst-free protocol for the highly regioselective hydroacylation of styrenes with hydrazones derived from naturally abundant aldehydes.This protocolgeneratedlinearketoneswith goodfunctional...Wereport a base-promoted catalyst-free protocol for the highly regioselective hydroacylation of styrenes with hydrazones derived from naturally abundant aldehydes.This protocolgeneratedlinearketoneswith goodfunctional grouptolerance anda broadsubstrate scope under mild conditions.Mechanistic studies showed that the addition of hydrazone anion to a styrene double bond was the key step,different from previoushydroacylationpathways(viaorganometallic complexes or radical intermediates).展开更多
On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in...On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in dimethyl sulfoxide giving ethyl α-cyano-α- (p-nitrophenyl) acetate is shown to take place via the intermediacy of p-dinitrobenzene radical anion. The reaction rate goes faster than that between p-nitrohalobenzenes and the same sodium salt of ethyl α-cyanoacetate carbanion. There is an evidence for a single electron transfer mechanism.展开更多
Structural effect of substituents directly bonded to carbanions bearing a phosphorate moiety is examined. Nucleophihc addition of phosphonate carbanion to 1-nitroalkene followed by subsequent reaction with chlorotrime...Structural effect of substituents directly bonded to carbanions bearing a phosphorate moiety is examined. Nucleophihc addition of phosphonate carbanion to 1-nitroalkene followed by subsequent reaction with chlorotrimethylsilane leads to a series of 2-isoxazoline based on the formation of an alkene and silyl nitronate as a 1,3-dipole. On the other hand, addition of carbanion derived from isocyanomethylphosphonate to nitroalkene with the formation of nitronate followed by intromolecular cyclization provides substituted phosphoryl pyrroles.展开更多
文摘The (Et_4N)_2[Fe_4(SPh)_10] stimulated reaction of α-bromonaphthalene with pinacolone carbanion in DMSO leads to the formation of 1-(α-naphthyl)pinacolone. The reaction is suggested in terms of SRN1 mechanism of aromatic nucleophillic substitution and has potential value in synthesis to obtain (-substituted naphthalene derivaties.
文摘The reactions of α-(alkoxysilyl)allyl anions 4 with electrophiles were studied. α-Alkylation with alkyl halides was favoured, whereas γ-selection was achieved in the reaction with aldehydes.
基金support provided by the National Key R&D Program of China (No.2017YFA0207302)the National Natural Science Foundation of China (Nos.21672176 and 21332007).
文摘Summary of main observation and conclusion Direct functionalization of alkenes and direct transformation of carboxamides are two exciting areas that have attracted considerable attention in recent years.We report herein that secondary amides,the least reactive derivatives of carbonyl compounds,upon activated with triflic anhydride,can serve as effective hydroacylating reagents in partner with alkenes to yield ketones at ambient temperature.The method was applied to the one-step synthesis of racemic dihydro-ar-turmerone.In this method,alkenes serve as surrogates of organometallic reagents,which allows the orthogonal chemoselective reactions.The ready availability of many olefins such as camphene and norbornene permits one-step ketone synthesis that would require several steps by conventional methods.
基金The authors are grateful for the financial support provided by the National Natural Science Foundation of China (Nos. 21672176 and 21332007)the National Key R&D Pregram of China (No. 2017YFA0207302).
文摘In recent years,exciting progress has been made in the field of direct transformation of amides,nevertheless,the condensation between two amides remains rare and restricted to homo-coupling reactions.Herein,we report the cross-coupling of secondary amides with tertiary amides,which provides a synthesis of ketones under mild conditions,and features the use of tertiary amides as surrogates of alkyl carbanions.The method relies on the coupling of enamines,generated from tertiary amides by catalytic partial reduction of tertiary amides with Vaska's catalyst,with nitrilium ions,formed in situ from secondary amides via activation with trifluoromethanesulfonic anhydride,and on the subsequent deformylation.
基金Supported by the National Natural Science Foundation of China (Grant No. 20832005)
文摘The (S)-sulfide 6 has been synthesized as a synthetic equivalent of novel 3-piperidinol N-α-carbanion B via deprotonation and lithium naphthanelide (LN)-mediated reductive lithiation. The reaction of the 3-piperidinol N-α-carbanion intermediate B with carbonyl compounds gave, besides some reduced product 2a, the desired α-hydroxyalkylation products 12-17 with excellent 2,3-diastereoselectivity. The reductive α-hydroxyalkylation with unsymmetric carbonyl compounds led to only 50:50 to 77:23 diastereoselectivities at the C-1' carbinol center.
基金from the National Natural Science Foundation of China(grant no.21971093)the International Joint Research Centre for Green Catalysis and Synthesis(grant no.2016B01017),and the 111 project.
文摘Wereport a base-promoted catalyst-free protocol for the highly regioselective hydroacylation of styrenes with hydrazones derived from naturally abundant aldehydes.This protocolgeneratedlinearketoneswith goodfunctional grouptolerance anda broadsubstrate scope under mild conditions.Mechanistic studies showed that the addition of hydrazone anion to a styrene double bond was the key step,different from previoushydroacylationpathways(viaorganometallic complexes or radical intermediates).
文摘On the basis of investigation of cyclic voltammetry, EPR spectroscopy and competition experiments, the nucleophilic substitution reaction of p- dinitrobenzene with the sodium salt of ethyl α-cyanoacetate carbanion in dimethyl sulfoxide giving ethyl α-cyano-α- (p-nitrophenyl) acetate is shown to take place via the intermediacy of p-dinitrobenzene radical anion. The reaction rate goes faster than that between p-nitrohalobenzenes and the same sodium salt of ethyl α-cyanoacetate carbanion. There is an evidence for a single electron transfer mechanism.
基金Project (No. 29672042, 29832050) supported by the National Natural Science Foundation of China.
文摘Structural effect of substituents directly bonded to carbanions bearing a phosphorate moiety is examined. Nucleophihc addition of phosphonate carbanion to 1-nitroalkene followed by subsequent reaction with chlorotrimethylsilane leads to a series of 2-isoxazoline based on the formation of an alkene and silyl nitronate as a 1,3-dipole. On the other hand, addition of carbanion derived from isocyanomethylphosphonate to nitroalkene with the formation of nitronate followed by intromolecular cyclization provides substituted phosphoryl pyrroles.
