Asymmetric counteranion-directed catalytic Hosomi-Sakurai reaction.

Counteranion control enables the enantioselective, organo Lewis acid catalyzed Hosomi-Sakurai reaction of (hetero)aromatic aldehydes and allylsilanes using an easily handled disulfonimide precatalyst (see scheme). The key to the success of this system is to turn the usually undesired silylium ion catalysis into the desired catalytic regime and pair the cation with an enantiopure disulfonimide anion, thereby applying the concept of asymmetric counteranion-directed catalysis.