Ir-Catalyzed Substitution of Propargylic-type Esters with Enoxysilanes

Propargylic-type acetates react readily with enoxysilanes in the presence of 1 mol % of [Ir(cod){P(OPh)3}2]OTf activated preliminarily with molecular H2 to give β-alkynyl ketones in high to excellent yields. Substitution at the propargyl carbon proceeds exclusively or selectively in most types of propargylic esters. Alternatively, the formation of the allenyl products is predominant in the reaction of esters, which have two phenyl groups on the propargyl carbon.