Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran der...Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.展开更多
Mono-substituted heterocyclic ketene aminals are formed by the reaction of 1-methyl-2-methylthio-imidazoline with active methylene compounds containinq an acetyl or benzoyl group by the elimination of both a methylthi...Mono-substituted heterocyclic ketene aminals are formed by the reaction of 1-methyl-2-methylthio-imidazoline with active methylene compounds containinq an acetyl or benzoyl group by the elimination of both a methylthio and an acyl group.This is resulted by the secondary reactio of the produced methanethiol to attack the more active carbonyl group.展开更多
A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL（lipase from porcine pancreas） with satis...A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL（lipase from porcine pancreas） with satisfied yields（49%–92%）.Moreover,PPL induces moderate Z/E selectivity in the Knoevenagel condensation.展开更多
An efficient synthesis of β-alkoxycarbonyl vinylsulfonium salts had been developed. Their reaction with indene-1,3-diones and other active methylene compounds provided cyclopropane carboxylates in good yields. A tent...An efficient synthesis of β-alkoxycarbonyl vinylsulfonium salts had been developed. Their reaction with indene-1,3-diones and other active methylene compounds provided cyclopropane carboxylates in good yields. A tentative reaction mechanism was proposed.展开更多
Eight new complexes with the formula [PhC_2C(OH)R^2R^2]Co_2(CO)_6 were prepared from phenyl substituted propargylic alcohols and dicobalt octacarbonyl.The reactions of these propargylio alcohol complexes with active m...Eight new complexes with the formula [PhC_2C(OH)R^2R^2]Co_2(CO)_6 were prepared from phenyl substituted propargylic alcohols and dicobalt octacarbonyl.The reactions of these propargylio alcohol complexes with active methylene compounds,2,4-pentanedione or ethyl acetoacetate,in the presnce of an acid,HBF_4(40％)+P_2O_5(in excess)or BF_3·Et_2O,at room temperature in dichlorome- thane were investigated.From the 1-alkyl substituted tertiary propargylic alcohol complexes,three new conjugated ene-yne complexes produced by intramolecular dehydration reaction were isolated in high yields(82—95％).On the other hand,four new alkylated complexes were obtained with satisfactory yields(44—66％)from the secondary propargylic alcohol complexes.The influence of other acids,phosphorus pentoxide and polyphosphoric acid,on both dehydration reaction and alkylated reaction was also studied.展开更多
Palladium-catalyzed allylation of carbonucleophiles has been widely used for carbon-carbon bond formation.Among the allylic compounds studied,allylic acetates were mostwidely used as precursors of(π-allyl)palladium i...Palladium-catalyzed allylation of carbonucleophiles has been widely used for carbon-carbon bond formation.Among the allylic compounds studied,allylic acetates were mostwidely used as precursors of(π-allyl)palladium intermediates.However,bases such as NaHmust be used to generate anions in this reaction.Recently,research on carrying out the palla-展开更多
基金the National Natural Science Foundation of China (No.20676123) for financial support.
文摘Catalyzed by ytterbium（III） triflate hydrate [Yb（OTf）3.xH20], the Michael addition and cyclocondensation of α,β-unsaturated ketones with active methylene compounds to afford the 1,4-adducts and benzo[b]pyran derivatives, respectively were studied.
文摘Mono-substituted heterocyclic ketene aminals are formed by the reaction of 1-methyl-2-methylthio-imidazoline with active methylene compounds containinq an acetyl or benzoyl group by the elimination of both a methylthio and an acyl group.This is resulted by the secondary reactio of the produced methanethiol to attack the more active carbonyl group.
基金the financial support from the National Natural Science Foundation of China (Nos. 21172093, 31070708, and 21072075)the Natural Science Foundation of Jilin Province of China (Nos. 201115039 and 20140101141JC)the Scientific Research Fund of Jilin University (No. 450060326007)
文摘A simple and efficient Knoevenagel condensation between a b-unsaturated aldehydes and active methylene compounds is reported.Notably,this condensation can be catalyzed by PPL（lipase from porcine pancreas） with satisfied yields（49%–92%）.Moreover,PPL induces moderate Z/E selectivity in the Knoevenagel condensation.
基金the National Natural Science Foundation of China (Nos. 21772240, 21472248)National Science and Technology Major Project of the Ministry of Science and Technology of China (No. 2017ZX09305010)+2 种基金Guangzhou Science Technology and Innovation Commission(No. 201707010210)Department of Science and Technology of Guangdong Province(Nos. 2017A020211011,2017A020211027)China Scholarship Council (No. 201608440090)
文摘An efficient synthesis of β-alkoxycarbonyl vinylsulfonium salts had been developed. Their reaction with indene-1,3-diones and other active methylene compounds provided cyclopropane carboxylates in good yields. A tentative reaction mechanism was proposed.
基金Work supported by the National Natural Science Foundation of China.
文摘Eight new complexes with the formula [PhC_2C(OH)R^2R^2]Co_2(CO)_6 were prepared from phenyl substituted propargylic alcohols and dicobalt octacarbonyl.The reactions of these propargylio alcohol complexes with active methylene compounds,2,4-pentanedione or ethyl acetoacetate,in the presnce of an acid,HBF_4(40％)+P_2O_5(in excess)or BF_3·Et_2O,at room temperature in dichlorome- thane were investigated.From the 1-alkyl substituted tertiary propargylic alcohol complexes,three new conjugated ene-yne complexes produced by intramolecular dehydration reaction were isolated in high yields(82—95％).On the other hand,four new alkylated complexes were obtained with satisfactory yields(44—66％)from the secondary propargylic alcohol complexes.The influence of other acids,phosphorus pentoxide and polyphosphoric acid,on both dehydration reaction and alkylated reaction was also studied.
文摘Palladium-catalyzed allylation of carbonucleophiles has been widely used for carbon-carbon bond formation.Among the allylic compounds studied,allylic acetates were mostwidely used as precursors of(π-allyl)palladium intermediates.However,bases such as NaHmust be used to generate anions in this reaction.Recently,research on carrying out the palla-
