Hydrosilylation and Mukaiyama aldol-type reaction of quinolines and hydrosilylation of imines catalyzed by a mesoionic carbene-stabilized borenium ion

Aldimines and ketimines containing electron-donating and electron-withdrawing groups can be hydrosilylated with borenium catalysts at as low as 1 mol% catalyst loading at room temperature, providing the corresponding secondary amines in excellent yields. Reactions with 2-phenylquinoline gave the 1,4-hydrosilylquinoline product selectively which can be further functionalized in a one-pot synthesis to give unique γ-amino alcohol derivatives. Control experiments suggest that the borenium ion catalyzes both the hydrosilylation and subsequent addition to the aldehyde. Aldimines and ketimines are hydrosilylated with borenium catalysts at room temperature, giving the corresponding amines in excellent yields. For quinolines, subsequent Mukaiyama aldol reactions can be performed, which are also borenium-ion catalyzed.