Visible light-mediated cobalt and photoredox dual-catalyzed asymmetric reductive coupling of biaryl dialdehydes and aryl iodides

Secondary alcohols bearing both axial and central chirality comprise attractive biological activity, and also exhibit excellent chiral induction in asymmetric reactions. However, only very limited asymmetric catalytic approaches were developed for their catalytic synthesis. We herein describe visible light-mediated cobalt-catalyzed asymmetric reductive Grignard-type addition of axially prochiral biaryl dialdehydes with aryl iodides, leading to the direct construction of axially chiral secondary alcohols bearing aldehyde groups. Preliminary mechanistic studies indicate efficient kinetic recognition of diastereomers might occur to improve the diastereoselectivity, which might open a new avenue for the challenging cascade construction of multiple chiral elements. This protocol features excellent enantio- and diastereoselectivity, green and mild conditions, simple operation, and broad substrate scope, providing a modular platform for the synthesis of secondary axially chiral alcohols.