By the addition of rice wine koji, enhancement of the reactivity was observed for the baker＇s yeast reduction of β-keto esters into （S）-β-hydroxy esters with high enantiomeric purity （73-98%）.
An efficient procedure for the synthesis ofβ-keto esters from the reaction of aldehydes and ethyl diazoacetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic p...An efficient procedure for the synthesis ofβ-keto esters from the reaction of aldehydes and ethyl diazoacetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic procedure has the advantages of easily available catalyst, mild reaction conditions, high yields, and easy work-up.展开更多
An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzo- xazoles with β-keto esters as starting materials under mild reaction conditions, during which other functional groups ...An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzo- xazoles with β-keto esters as starting materials under mild reaction conditions, during which other functional groups are bearable from reactants to products.展开更多
An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） a...An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） at room temperature to selectively afford the corresponding α-monobromination products in excellent yields. It is noteworthy that the reaction was conducted under mild, environmentally benign and catalyst-free conditions.展开更多
2-Cetyl-3-20 keto acid（N-ethyl perfluorinated octyl sulfonamide） N-ethyl ester was synthesized by the reaction of N-ethyl-N-hydroxyethyl perfluorinated octyl sulfonamide and alky ketene dimer. The experimental resul...2-Cetyl-3-20 keto acid（N-ethyl perfluorinated octyl sulfonamide） N-ethyl ester was synthesized by the reaction of N-ethyl-N-hydroxyethyl perfluorinated octyl sulfonamide and alky ketene dimer. The experimental results show that the yield of products can be 89% when the molar ratio of perfluorinated octyl sulfonamide to ketene dimer is 1 ： 1.1 and the reaction lasts about four hours at 80 ℃. The structure of the product was characterized by FTIR and ^1HNMR. The product can dissolve in polar solvents such as NMP, DMAC, THF, DMSO, CHCl3, and 10% weight-loss temperature measured by TGA is 202℃.展开更多
An efficient asymmetric domino reaction of amino aldehyde to β,γ-unsaturated a-keto esters was achieved by using trans-perhydroindolic acid ld as a chiral organocatalyst with excellent asymmetric behavior. Under the...An efficient asymmetric domino reaction of amino aldehyde to β,γ-unsaturated a-keto esters was achieved by using trans-perhydroindolic acid ld as a chiral organocatalyst with excellent asymmetric behavior. Under the opti- mal reaction conditions, products with more than 99% de and up to 93% ee were obtained in high chemical yield （up to 98%） for a series of β,γ-unsaturated a-keto esters. The methodology provided an efficient route to dihydro- pyran derivatives containing many substituent groups （including amino groups）.展开更多
Enantioselective chlorination of b-keto esters and amides catalyzed by squaramide-linked bisoxazoline ligand–Cu（OAc）2complexes was investigated. The corresponding chlorinated products were obtained in excellent yie...Enantioselective chlorination of b-keto esters and amides catalyzed by squaramide-linked bisoxazoline ligand–Cu（OAc）2complexes was investigated. The corresponding chlorinated products were obtained in excellent yields with moderate enantioselectivities. The effect of solvent, temperature, Lewis acid, and ligand structure on the reaction is discussed. This was the first investigation of catalytic asymmetric achlorination of b-keto amides. This study has highlighted that a simple chiral squaramide–oxazoline with cheap Cu（OAc）2 H2 O complexes can catalyze this chlorination.展开更多
The ferric perchlorate-promoted reaction of [60]fullerene (C60) with ethyl 2-methylacetoacetate generates fullerenyl hemiketal as a mixture of trans and cis isomers,while the reaction with ethyl acetoacetate gives a C...The ferric perchlorate-promoted reaction of [60]fullerene (C60) with ethyl 2-methylacetoacetate generates fullerenyl hemiketal as a mixture of trans and cis isomers,while the reaction with ethyl acetoacetate gives a C 60-fused dihydrofuran derivative.A possible reaction mechanism for the formation of these products is proposed.展开更多
Optically pure(R)-γ-and(R)-δ-lactones can be prepared by intramolecular cyclization of chiral hydroxy acids/esters reduced asymmetrically from γ-and δ-keto acids/esters using Saccharomyces cerevisiae(S.cerevisiae)...Optically pure(R)-γ-and(R)-δ-lactones can be prepared by intramolecular cyclization of chiral hydroxy acids/esters reduced asymmetrically from γ-and δ-keto acids/esters using Saccharomyces cerevisiae(S.cerevisiae) as a whole-cell biocatalyst.However,some of the enzymes catalyzing these reactions in S.cerevisiae are still unknown up to date.In this report,two carbonyl reductases,OdCRl and OdCR2,were successfully discovered,and cloned from S.cerevisiae using a genome-mining approach,and overexpressed in Escherichia coli(E.coli).Compared with OdCR1,OdCR2 can reduce 4-oxodecanoic acid and 5-oxodecanoic acid asymmetrically with higher stereoselectivity,generating(R)-γ-decalactone(99% ee) and(R)-δ-decalactone(98% ee) in 85% and 92%yields,respectively.This is the first report of native enzymes from S.cerevisiae for the enzymatic synthesis of chiral γ-and δ-lactones which is of wide uses in food and cosmetic industries.展开更多
文摘By the addition of rice wine koji, enhancement of the reactivity was observed for the baker＇s yeast reduction of β-keto esters into （S）-β-hydroxy esters with high enantiomeric purity （73-98%）.
基金Supported by the Special Scientific Research Project of Shaanxi Education Commission(No.08JZ09) the Science Re-search Foundation of Baoji University of Arts and Sciences, China(No.ZK064)
文摘An efficient procedure for the synthesis ofβ-keto esters from the reaction of aldehydes and ethyl diazoacetate catalyzed by iodine at room temperature under solvent-free conditions has been described. The catalytic procedure has the advantages of easily available catalyst, mild reaction conditions, high yields, and easy work-up.
基金Supported by the National Natural Science Foundation of China(No.20874105)the Foundation of Hebei Education Department China(No.2010268)
文摘An efficient synthetic method was developed to synthesize 2-substituted benzimidazoles and benzo- xazoles with β-keto esters as starting materials under mild reaction conditions, during which other functional groups are bearable from reactants to products.
基金Project supported by the Key Project of Chinese Ministry of Education （No. 206102）, Fok Ying Dong Education Foundation （No. 101012）, Scientific Research Fund of Hunan Provincial Education Department （No. 05B038）, Hunan Provincial Natural Science Foundation of China （No. 05JJ1002） and the National Natural Science Foundation of China （Nos. 20572020, 20202002）.
文摘An efficient bromination protocol for the synthesis of α-bromo-β-keto esters has been developed. In PEG-400 （poly（ethylene glycol-400））, a variety of β-keto esters were treated with NBS （N-bromosuccinimide） at room temperature to selectively afford the corresponding α-monobromination products in excellent yields. It is noteworthy that the reaction was conducted under mild, environmentally benign and catalyst-free conditions.
基金Funded by the National High-Tech Foundation(No. 2003 AA305920)
文摘2-Cetyl-3-20 keto acid（N-ethyl perfluorinated octyl sulfonamide） N-ethyl ester was synthesized by the reaction of N-ethyl-N-hydroxyethyl perfluorinated octyl sulfonamide and alky ketene dimer. The experimental results show that the yield of products can be 89% when the molar ratio of perfluorinated octyl sulfonamide to ketene dimer is 1 ： 1.1 and the reaction lasts about four hours at 80 ℃. The structure of the product was characterized by FTIR and ^1HNMR. The product can dissolve in polar solvents such as NMP, DMAC, THF, DMSO, CHCl3, and 10% weight-loss temperature measured by TGA is 202℃.
文摘An efficient asymmetric domino reaction of amino aldehyde to β,γ-unsaturated a-keto esters was achieved by using trans-perhydroindolic acid ld as a chiral organocatalyst with excellent asymmetric behavior. Under the opti- mal reaction conditions, products with more than 99% de and up to 93% ee were obtained in high chemical yield （up to 98%） for a series of β,γ-unsaturated a-keto esters. The methodology provided an efficient route to dihydro- pyran derivatives containing many substituent groups （including amino groups）.
基金financial support from the National Natural Science Foundation of China(Nos.21072010 and 21272024)
文摘Enantioselective chlorination of b-keto esters and amides catalyzed by squaramide-linked bisoxazoline ligand–Cu（OAc）2complexes was investigated. The corresponding chlorinated products were obtained in excellent yields with moderate enantioselectivities. The effect of solvent, temperature, Lewis acid, and ligand structure on the reaction is discussed. This was the first investigation of catalytic asymmetric achlorination of b-keto amides. This study has highlighted that a simple chiral squaramide–oxazoline with cheap Cu（OAc）2 H2 O complexes can catalyze this chlorination.
基金supported by the National Natural Science Foundation of China(20972145,21132007,21102041)
文摘The ferric perchlorate-promoted reaction of [60]fullerene (C60) with ethyl 2-methylacetoacetate generates fullerenyl hemiketal as a mixture of trans and cis isomers,while the reaction with ethyl acetoacetate gives a C 60-fused dihydrofuran derivative.A possible reaction mechanism for the formation of these products is proposed.
基金financially sponsored by the National Key Research and Development Program of China (2016YFA0204300, 2019YFA09005000)the National Natural Science Foundation of China (21536004, 21776085, 21871085)+2 种基金the Natural Science Foundation of Shanghai (18ZR1409900)Key Project of the Shanghai Science and Technology Committee (18DZ1112703)the Fundamental Research Funds for the Central Universities (WF1714026)。
文摘Optically pure(R)-γ-and(R)-δ-lactones can be prepared by intramolecular cyclization of chiral hydroxy acids/esters reduced asymmetrically from γ-and δ-keto acids/esters using Saccharomyces cerevisiae(S.cerevisiae) as a whole-cell biocatalyst.However,some of the enzymes catalyzing these reactions in S.cerevisiae are still unknown up to date.In this report,two carbonyl reductases,OdCRl and OdCR2,were successfully discovered,and cloned from S.cerevisiae using a genome-mining approach,and overexpressed in Escherichia coli(E.coli).Compared with OdCR1,OdCR2 can reduce 4-oxodecanoic acid and 5-oxodecanoic acid asymmetrically with higher stereoselectivity,generating(R)-γ-decalactone(99% ee) and(R)-δ-decalactone(98% ee) in 85% and 92%yields,respectively.This is the first report of native enzymes from S.cerevisiae for the enzymatic synthesis of chiral γ-and δ-lactones which is of wide uses in food and cosmetic industries.
