Iridium-Catalyzed Reduction of Alkyl Halides by Triethylsilane

A highly active cationic Ir(III) hydride complex catalyzes the reduction of primary, secondary, and tertiary chlorides, bromides, and iodides as well as certain fluorides by Et3SiH. The catalytic cycle appears to operate by a unique process in which an electrophilic iridium silane complex acts as a silylating reagent to produce a silyl-substituted halonium ion which is then readily reduced by the nucleophilic dihydride formed following silyl transfer.