Asymmetric cooperative catalysis in the conjugate addition of pyrazolones to nitroolefins and subsequent dearomative chlorination  

作　　者：ZHANG KeFeng LI Feng NIE Jing MA JunAn 

机构地区：[1]Department of Chemistry,Tianjin University

出　　处：《Science China Chemistry》2014年第2期265-275,共11页中国科学（化学英文版）

基　　金：supported by the National Natural Science Foundation of China(21172170 and 21225208);the National Basic Research Program of China(973 Program,2014CB745100)

摘　　要：Over the past decade many bifunctional amine-thioureas have been developed as active metal-free organocatalysts. Coopera-tive catalysis of these amino-thioureas allows high reaction rates and excellent transfer of stereocbemical information. Despite these impressive advances, the design of new high-performance catalysts for applications in asymmetric catalytic reactions is of ongoing interest in organic chemistry. Herein we describe a cooperative catalyst system consisting of a chiral amine thiourea and an achiral organic acid that promotes the conjugate addition of 4-nonsubstituted pyrazolones to nitroolefins and subsequent dearomative chlorination. The corresponding adducts and the subsequent products were obtained in high to excel lent yields （up to 99%） and high stereoselectivities （up to 99/1 dr, 98% ee） under mild reacton conditions. These transforma tions provide an easy access to enantio-enriched pvrazole derivatives, which could possess Potential oharmaceutical activity.Over the past decade many bifunctional amine-thioureas have been developed as active metal-free organocatalysts.Cooperative catalysis of these amino-thioureas allows high reaction rates and excellent transfer of stereochemical information.Despite these impressive advances,the design of new high-performance catalysts for applications in asymmetric catalytic reactions is of ongoing interest in organic chemistry.Herein we describe a cooperative catalyst system consisting of a chiral aminethiourea and an achiral organic acid that promotes the conjugate addition of 4-nonsubstituted pyrazolones to nitroolefins and subsequent dearomative chlorination.The corresponding adducts and the subsequent products were obtained in high to excellent yields(up to 99%)and high stereoselectivities(up to 99/1 dr,98%ee)under mild reaction conditions.These transformations provide an easy access to enantio-enriched pyrazole derivatives,which could possess potential pharmaceutical activity.

关 键 词：cooperative catalysis conjugate addition amine-thioureas PYRAZOLONE NITROOLEFIN CHLORINATION 

分 类 号：O621.3[理学—有机化学]