Iridium-Catalyzed C-C Coupling of a Simple Propargyl Ether with Primary Alcohols: Enantioselective Homoaldol Addition via Redox-Triggered (Z)-Siloxyallylation

摘要

A chiral iridium complex formed in situ from [Ir(cod)Cl]_2 and (R)-H_8-BINAP is found to catalyze the direct enantioselective C-C coupling of a simple propargyl ether, TIPSOCH_2C≡CH, with primary alcohols to form γ-hydroxy (Z)-enol silanes with uniformly high enantioselecrivity and complete alkene (Z)-stereo-selectivity. As corroborated by deuterium labeling studies, these studies represent the first examples of 1,2-hydride shift-enabled π-allyl formation in the context of iridium catalysis.