Gold-Catalyzed Oxidative Hydrative Alkenylations of Propargyl Aryl Thioethers with Quinoline N-Oxides Involving a 1,3-Sulfur Migration.

This work reports gold-catalyzed oxidative alkenylations of quinoline N-oxides with propargyl aryl thioethers to afford 3-hydroxy-1-alkylidenephenylthiopropan-2-one via a 1,3-sulfur group migration. The mechanism of this reaction is postulated to involve an α-oxo gold carbene intermediate followed by formation of a four-membered sulfonium ring that is ring-opened by one HO to form a gold enolate. A final condensation of this enolate with a second quinoline N-oxide delivers an alkenylation product accompanied by a 1,3-sulfur shift.