A Stereoselective Switch: Enantiodivergent Approach to the Synthesis of Isoflavanones

A modular six‐step asymmetric synthesis of two naturally occurring and three non‐natural isoflavanones containing tertiary α‐aryl carbonyls is reported. This synthetic route, utilising a Pd‐catalyzed decarboxylative asymmetric protonation, produces isoflavanones in excellent enantioselectivities from 76–97 %. A switch in the sense of stereoinduction was observed when different H + sources were employed, showing the first example of dual stereocontrol in an asymmetric protonation reaction. The first enantioselective synthesis of the naturally occurring isoflavanones sativanone and 3‐ o ‐methylviolanone has been accomplished.