Enantioselective N‐Heterocyclic Carbene Catalysis via the Dienyl Acyl Azolium

Abstract Herein we report the enantioselective N‐heterocyclic carbene catalyzed (4+2) annulation of the dienyl acyl azolium with enolates. The reaction exploits readily accessible acyl fluorides and TMS enol ethers to give a range of highly enantio‐ and diastereo‐enriched cyclohexenes (most >97:3 er and >20:1 dr). The reaction was found to require high nucleophilicity NHC catalysts with mechanistic studies supporting a stepwise 1,6‐addition/β‐lactonization.