Access to axially chiral aryl 1,3-dienes by transient group directed asymmetric C–H alkenylations

Abstract

We present a Pd-catalyzed atroposelective preparation of aryl 1,3-dienes from readily available styrenes and olefins through an aldehyde derived transient chiral auxiliary, proceeding by enantioselective olefinic C–H alkenylation of styrenes via seven-membered endo-cyclometallation. The generality of the protocol has been demonstrated by the smooth conversion of a wide range of 2-vinyl benzaldehyde derivatives to afford up to 99% yields and high to excellent enantioselectivities (up to >99% ee). The derived axially chiral carboxylic acid was demonstrated to be a more efficient ligand in the Cp*Co(III)-catalyzed asymmetric C(sp³)–H alkylation.