(-)-β-Pinene-Derived N-Heterocyclic Carbenes: Application to Highly Enantioselective Intramolecular Stetter Reaction

Novel chiral N-heterocyclic carbenes derived from ()(-)-beta-pinene have been synthesized and used as efficient catalysts for the intramolecular Stetter reaction. Mono-, di-, and trisubstituted 4-chromanone derivatives have been obtained almost quantitatively and with high enantioselectivity up to 99:1 er.