Catalytic Enantioselective Protonation of Gold Enolates Enabled by Cooperative Gold(I) Catalysis.

Enantioselective protonation is a versatile approach to the construction of tertiary α-stereocenters, which are common structural motifs in various natural products and biologically relevant compounds. Herein we report a mild access to these chiral centers using cooperative gold(I) catalysis. From cyclic ketone enol carbonates, this asymmetric catalysis provides highly enantioselective access to cyclic ketones featuring an α tertiary chiral center, including challenging 2-methylsuberone. In combination with the gold-catalyzed formation of cyclopentadienyl carbonates in a one-pot, two-step process, this chemistry enables expedient access to synthetically versatile α'-chiral cyclopentenones with excellent enantiomeric excesses from easily accessible enynyl carbonate substrates.