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 Et 3 SiH. 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.