Enantioselective intermolecular all-carbon [4+2] annulation via N-heterocyclic carbene organocatalysis

The challenge of asymmetric intermolecular all-carbon [4+2] annulation via α,β-unsaturated acyl azoliums was addressed with 2-acyloxy-3-butenones as suitable dienolate precursors, and a variety of highly functionalized cyclohexene products were delivered at a high level of enantioselectivity.