N-Heterocyclic carbene-catalyzed enantioselective synthesis of functionalized cyclopentenes via α,β-unsaturated acyl azoliums.

Highly enantioselective NHC-organocatalyzed synthesis of functionalized cyclopentenes proceeding via α,β-unsaturated acyl azolium intermediates is reported. The organocascade reaction of modified enals with malonic ester derivatives having a γ-benzoyl group involves the Michael-intramolecular aldol-β-lactonization-decarboxylation sequence to deliver cyclopentenes in good yields and excellent ee values.