One-Pot Enol Silane Formation-Alkylation of Ketones with Propargyl Carboxylates Promoted by Trimethylsilyl Trifluoromethanesulfonate.

Ketones readily undergo conversion to enol silanes in the presence of a trialkylamine base and trimethylsilyl trifluoromethanesulfonate (TMSOTf) and add to propargyl cations to yield ß-alkynyl ketones. The propargyl cations are generated in the same reaction flask through the TMSOTf-promoted ionization of propargyl acetates or propargyl propionates. A range of enol silane precursors and propargyl carboxylates reacts efficiently (20 examples, up to 99% yield). Cyclization of a representative product in the presence of TMSOTf provided 61% yield of the trisubstituted furan.