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
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
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
MCH 2(OH) and CH 3OM(M=-, Li, Na) were calculated by means of ab initio method at the MP2/631+G* level. The results show that the metals have the ability to localize charge on O in CH 3OM(M= Li, Na). MCH 2(OH)(M=L...MCH 2(OH) and CH 3OM(M=-, Li, Na) were calculated by means of ab initio method at the MP2/631+G* level. The results show that the metals have the ability to localize charge on O in CH 3OM(M= Li, Na). MCH 2(OH)(M=Li, Na) has four possible structures, among which carbonoxygenbridged structure 1 is the most stable and observable kinetically. For MCH 2(OH)(M=Li, Na), the existence of the metal increases the rigidity of the carbon configuration. This may be the reason why MCH 2(OR)(M=Li, Na) is widely used in stereoselective syntheses.展开更多
An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially...An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially formed by introducing an acyl group,then it was trapped by another acyl group to form 1,3-diketone.This method not only provided the gateway to obtain a series of 1,3-diketones,but also afforded an operationally simple and efficient access to pyrazoles and isoxazoles.展开更多
6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido[3,2-d]pyrimidin-2-ol(compound 9)was synthe sized from 6-methylpyrimidine-2,4-diol(compound 1)through the crucial steps of 6-methyl alkylating and intramo lecular cycl...6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido[3,2-d]pyrimidin-2-ol(compound 9)was synthe sized from 6-methylpyrimidine-2,4-diol(compound 1)through the crucial steps of 6-methyl alkylating and intramo lecular cyclization.The assignment of the structure of compound 9 was performed by its spectral data,1H NMR,13C NMR,HMBC,and HRMS spectra.展开更多
A novel carboanion relay enabled[1+2+2+1]cascade cyclization reaction utilizing rarely used isatin-derived 6-silylcarbinols and aryl methyl ketones as readily available starting materials has been developed,endowing a...A novel carboanion relay enabled[1+2+2+1]cascade cyclization reaction utilizing rarely used isatin-derived 6-silylcarbinols and aryl methyl ketones as readily available starting materials has been developed,endowing a powerful platform for the streamline synthesis of cyclohexane-tethered bispirooxindoles in decent yields with high diastereoselectivities.This protocol was realized by merging triple Michael additions and C-C bond cleavage using Cs_(2)CO_(3) as a robust promotor under transition metal-free conditions.The practicability of this method is demonstrated by its simple operation,broad substrate scope as wellas easy scale-up.展开更多
The nucleophilic trifluoromethylation involving trifluoromethyllithium(LiCF_(3))species has been an open question since Haszeldine attempted to prepare LiCF_(3) in 1949.Indeed,LiCF_(3) has been used for electrophilic ...The nucleophilic trifluoromethylation involving trifluoromethyllithium(LiCF_(3))species has been an open question since Haszeldine attempted to prepare LiCF_(3) in 1949.Indeed,LiCF_(3) has been used for electrophilic difluoromethylene transfer processes(via elimination of fluoride ions)since 2010.Herein,we demonstrated that by using a polar solvent such as dimethylformamide(DMF)or hexamethylphosphoramide(HMPA)as the lithium chelator,the in situ deprotonation of fluoroform(HCF_(3))with lithium hexamethyldisilazide(LiHMDS)could generate a tamed LiCF_(3) species that is sufficiently persistent to undergo nucleophilic trifluoromethylation reaction.The nucleophilic reactivity of LiCF_(3) species was probed with several electrophiles,including arylsulfonyl fluorides,diaryl ketones,and silyl chlorides.The synthetic utility of this method is demonstrated with the efficient synthesis of highly valuable triflones that are otherwise difficult to synthesize from HCF_(3) using potassium or sodium bases.This work not only showcases a new protocol for the utilization of fluoroform(an industrial waste with high global warming potential)as the trifluoromethylation reagent,but also provides intriguing insights into the harnessing of nucleophilic reactivity of the transient LiCF_(3) species.展开更多
Through the chiral-pool based synthesis of both enantiomers of schweinfurthinol, it has been proven that this natural product isolated from the seeds of Canarium schweinfurthii possesses an （S） configuration. The op...Through the chiral-pool based synthesis of both enantiomers of schweinfurthinol, it has been proven that this natural product isolated from the seeds of Canarium schweinfurthii possesses an （S） configuration. The optical rotation data for pure schweinfurthinol is also updated.展开更多
p-Quinols are ubiquitous structural motifs of various natural products and pharmaceutical compounds,and versatile building blocks in synthetic chemistry.The reported methods for the synthesis of p-quinol require stoic...p-Quinols are ubiquitous structural motifs of various natural products and pharmaceutical compounds,and versatile building blocks in synthetic chemistry.The reported methods for the synthesis of p-quinol require stoichiometric amounts of oxidants.Molecular oxygen is considered as an ideal oxidant due to its natural,inexpensive,and environmentally friendly characteristics.During the ongoing research of C–H bond hydroxylation,we found that multi-alkyl phenols could react with molecular oxygen under mild conditions.Herein,we describe an efficient oxidative de-aromatization of multi-alkyl phenols to p-quinols.1 atm of molecular oxygen was used as the oxidant.Many multi-alkyl phenols could react smoothly at room temperature.Isotopic labeling experiment was also performed,and the result proved that the oxygen atom in the produced hydroxyl group is from molecular oxygen.展开更多
Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of amo...Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of among molecules of the same compound It provides a new and convenient method to synthesize perhaloal-kanes Apparently,it pertains to an amomc mechanism,i e.the reaction is initiated by halophilic attack on C-X bonds by the base,and an intermediate carbanion is formed.Distributions of the products depend on the equilibria involving all carbanion intermediates and perhaloalkane product molecules.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
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.
基金Supported by the National Science Fund for Distinguished Young Investigators the NNSF ofChina (20272048+2 种基金 203900505) the Ministry of Education (Key Project 104201) and the Specialized Research Fundfor the Doctoral Program of Higher Education (20020384004)
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.
基金Supported by the National Natural Science Foundation of China(No. 29503019,29773025) and the Chinese Uni-versity Doctoral Foun
文摘MCH 2(OH) and CH 3OM(M=-, Li, Na) were calculated by means of ab initio method at the MP2/631+G* level. The results show that the metals have the ability to localize charge on O in CH 3OM(M= Li, Na). MCH 2(OH)(M=Li, Na) has four possible structures, among which carbonoxygenbridged structure 1 is the most stable and observable kinetically. For MCH 2(OH)(M=Li, Na), the existence of the metal increases the rigidity of the carbon configuration. This may be the reason why MCH 2(OR)(M=Li, Na) is widely used in stereoselective syntheses.
基金the National Natural Science Foundation of China(Nos.91745110,21673261,21603245,21703265,21872156,21802150,21773210 and 21603190)Natural Science Foundation of Jiangsu Province(Nos.BK20190002,BK20181194 and BK20180247)+1 种基金Support from the Young Elite Scientist Sponsorship Program by CAST(No.YESS20170217)the Youth Innovation Promotion Association CAS(No.2018458)。
文摘An efficient protocol for the synthesis of asymmetric 1,3-diketones was reported through diacylation of1,1-diborylalkanes using two different acyl sources.In this transfo rmation,an enolate boron species was initially formed by introducing an acyl group,then it was trapped by another acyl group to form 1,3-diketone.This method not only provided the gateway to obtain a series of 1,3-diketones,but also afforded an operationally simple and efficient access to pyrazoles and isoxazoles.
基金Supported by the National Natural Science Foundation of China(Nos.20672008,20972011)the PhD Foundation of the Ministry of Education of China
文摘6-(Bromomethyl)-4-methoxy-5,6,7,8-tetrahydropyrido[3,2-d]pyrimidin-2-ol(compound 9)was synthe sized from 6-methylpyrimidine-2,4-diol(compound 1)through the crucial steps of 6-methyl alkylating and intramo lecular cyclization.The assignment of the structure of compound 9 was performed by its spectral data,1H NMR,13C NMR,HMBC,and HRMS spectra.
基金support of National Natural Science Foundation of China(21901193 and 22271314)the innovation foundation of Key Laboratory of Green Chemical Engineering Process of Ministry of Education(GCX2023002).
文摘A novel carboanion relay enabled[1+2+2+1]cascade cyclization reaction utilizing rarely used isatin-derived 6-silylcarbinols and aryl methyl ketones as readily available starting materials has been developed,endowing a powerful platform for the streamline synthesis of cyclohexane-tethered bispirooxindoles in decent yields with high diastereoselectivities.This protocol was realized by merging triple Michael additions and C-C bond cleavage using Cs_(2)CO_(3) as a robust promotor under transition metal-free conditions.The practicability of this method is demonstrated by its simple operation,broad substrate scope as wellas easy scale-up.
基金support of this work by the National Key Research and Development Program of China(2021YFF0701700)the National Natural Science Foundation of China(22271299,22261132514 and 22301308)+2 种基金the Strategic Priority Research Program of the Chinese Academy of Sciences(XDB0590000)the Natural Science Foundation of Shandong Province(ZR2021LFG006 and ZR2023LFG003)the Shandong Dongyue Polymer Material Co.Ltd.is gratefully acknowledged。
文摘The nucleophilic trifluoromethylation involving trifluoromethyllithium(LiCF_(3))species has been an open question since Haszeldine attempted to prepare LiCF_(3) in 1949.Indeed,LiCF_(3) has been used for electrophilic difluoromethylene transfer processes(via elimination of fluoride ions)since 2010.Herein,we demonstrated that by using a polar solvent such as dimethylformamide(DMF)or hexamethylphosphoramide(HMPA)as the lithium chelator,the in situ deprotonation of fluoroform(HCF_(3))with lithium hexamethyldisilazide(LiHMDS)could generate a tamed LiCF_(3) species that is sufficiently persistent to undergo nucleophilic trifluoromethylation reaction.The nucleophilic reactivity of LiCF_(3) species was probed with several electrophiles,including arylsulfonyl fluorides,diaryl ketones,and silyl chlorides.The synthetic utility of this method is demonstrated with the efficient synthesis of highly valuable triflones that are otherwise difficult to synthesize from HCF_(3) using potassium or sodium bases.This work not only showcases a new protocol for the utilization of fluoroform(an industrial waste with high global warming potential)as the trifluoromethylation reagent,but also provides intriguing insights into the harnessing of nucleophilic reactivity of the transient LiCF_(3) species.
基金Project supported by the National Basic Research Program of China （973 Program） （No. 2010CB833200）, the National Natural Science Foundation of China （Nos. 21172247, 21032002, 20921091, 20672129, 20621062, 20772143） and the Chinese Academy of Sciences （＂Knowledge Innovation＂, KJCX2.YW.H08）.
文摘Through the chiral-pool based synthesis of both enantiomers of schweinfurthinol, it has been proven that this natural product isolated from the seeds of Canarium schweinfurthii possesses an （S） configuration. The optical rotation data for pure schweinfurthinol is also updated.
基金supported by the National Natural Science Foundation of China(21325206,21172006)the Key Laboratory of Oil and Gas Fine Chemicals(XJDX0908-2013-2)
文摘p-Quinols are ubiquitous structural motifs of various natural products and pharmaceutical compounds,and versatile building blocks in synthetic chemistry.The reported methods for the synthesis of p-quinol require stoichiometric amounts of oxidants.Molecular oxygen is considered as an ideal oxidant due to its natural,inexpensive,and environmentally friendly characteristics.During the ongoing research of C–H bond hydroxylation,we found that multi-alkyl phenols could react with molecular oxygen under mild conditions.Herein,we describe an efficient oxidative de-aromatization of multi-alkyl phenols to p-quinols.1 atm of molecular oxygen was used as the oxidant.Many multi-alkyl phenols could react smoothly at room temperature.Isotopic labeling experiment was also performed,and the result proved that the oxygen atom in the produced hydroxyl group is from molecular oxygen.
基金Project supported by the National Natural Science Foundation of China
文摘Halophilic attacks on C-X bonds (X=Br,Cl) by a base can easily initiate mtermolecular bromme-chlonne exchange reactions either among bromine-or chlorine-containing perhaloalkane molecules of different compounds of among molecules of the same compound It provides a new and convenient method to synthesize perhaloal-kanes Apparently,it pertains to an amomc mechanism,i e.the reaction is initiated by halophilic attack on C-X bonds by the base,and an intermediate carbanion is formed.Distributions of the products depend on the equilibria involving all carbanion intermediates and perhaloalkane product molecules.
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.
