Affiliation:
1. Center of Chemistry for Frontier Technologies Department of Chemistry Zhejiang University 310027 Hangzhou China
2. College of Material Chemistry and Chemical Engineering Key Laboratory of Organosilicon Chemistry and Material Technology Ministry of Education Hangzhou Normal University 311121 Hangzhou Zhejiang China
3. College of Biological Chemical Sciences and Engineering Jiaxing University 314001 Jiaxing Zhejiang China
Abstract
AbstractThe combination of achiral Cp*Rh(III) with chiral carboxylic acids (CCAs) represents an efficient catalytic system in transition metal‐catalyzed enantioselective C−H activation. However, this hybrid catalysis is limited to redox‐neutral C−H activation reactions and the adopt to oxidative enantioselective C−H activation remains elusive and pose a significant challenge. Herein, we describe the development of an electrochemical Cp*Rh(III)‐catalyzed enantioselective C−H annulation of sulfoximines with alkynes enabled by chiral carboxylic acid (CCA) in an operationally friendly undivided cell at room temperature. A broad range of enantioenriched 1,2‐benzothiazines are obtained in high yields with excellent enantioselectivities (up to 99 % yield and 98 : 2 er). The practicality of this method is demonstrated by scale‐up reaction in a batch reactor with external circulation. A crucial chiral Cp*Rh(III) intermediate is isolated, characterized, and transformed, providing rational support for a Rh(III)/Rh(I) electrocatalytic cycle.
Funder
National Natural Science Foundation of China
Fundamental Research Funds for the Central Universities
Natural Science Foundation of Zhejiang Province