Switchable Stereoselectivity in Bromoaminocyclization of Olefins: Using Brønsted Acids of Anionic Chiral Cobalt(III) Complexes

• Published in: Angewandte Chemie International Edition Vol. 56; no. 39; pp. 11931 - 11935
• Main Authors: Jiang, Hua‐Jie, Liu, Kun, Yu, Jie, Zhang, Ling, Gong, Liu‐Zhu
• Format: Journal Article
• Language: English
• Published: Germany Wiley Subscription Services, Inc 18-09-2017
• Edition: International ed. in English
• Subjects: Acids; Alkenes; Brønsted acid; Catalysts; Chemical industry; Cobalt; cyclization; Enantiomers; heterocycles; phase-transfer catalysis; Stereoselectivity; Substrates; Brønsted acid; cobalt; phase-transfer catalysis; heterocycles; cyclization
• ISSN: 1433-7851; 1521-3773
• DOI: 10.1002/anie.201705066

Brønsted acids of anionic chiral CoIII complexes act as bifunctional phase‐transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral CoIII‐templated Brønsted acids, with the same chiral ligands, enabled a switch in the enantioselective bromoaminocyclization of olefins to afford the two enantiomers of 2‐substituted pyrrolidines with high enantioselectivities (up to 99:1 e.r.).
Flip of the switch: Brønsted acids of anionic chiral CoIII complexes act as bifunctional phase‐transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral CoIII‐templated Brønsted acids, with the same chiral ligands, enabled a switch in the enantioselective bromoaminocyclization of olefins to afford the two enantiomers of the 2‐substituted pyrrolidines with high stereoselectivities.