N-Heterocyclic Carbene-Catalyzed (4 + 2) Cycloaddition/Decarboxylation of Silyl Dienol Ethers with α,β-Unsaturated Acid Fluorides

Herein we report the first all-carbon N-heterocyclic carbene-catalyzed (4 + 2) cycloaddition. The reaction proceeds with α,β-unsaturated acid fluorides and silyl dienol ethers and produces 1,3-cyclohexadienes with complete diastereocontrol (dr >20:1) while demonstrating a new type of reaction cascade exploiting α,β-unsaturated acyl azoliums.