Gold-catalyzed 5-exo-dig and 6-exo-dig selective cyclizations of alkynyl silyl enol ethers:: Efficient method for [3+2] and [4+2] annulations onto α,β-enones

An efficient method for the annulation of five- and six-membered rings onto alpha,beta-enones is described via gold-catalyzed 5- and 6-exo-dig selective cyclizations of alkynyl silyl enol ethers.