Highly chemoselective and stereoselective synthesis of Z-enol silanes

Three-component nickel-catalyzed couplings of enals, alkynes, and silanes have been developed as a new entry to enol silanes. The enol silane and a trisubstituted alkene are both formed with > 98:2 stereoselectively, and the reaction tolerates a broad range of functionality including aldehydes, ketones, esters, free hydroxyls, and basic secondary amines. A mechanistic pathway involving the formation of a metallacycle that possesses and eta(1) nickel O-enolate motif explains the high level of stereoselection.