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

Brønsted acids of anionic chiral Co(III) complexes act as bifunctional phase-transfer catalysts to shuttle the substrates across the solvent interface and control stereoselectivity. The diastereomeric chiral Co(III) -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.).