Intramolecular Tandem Michael-Type Addition/Aldol Cyclization Induced by TiCl₄−R₄NX Combinations

Treatment of formyl α,β-enones with a TiCl₄−R₄NX combination induces an intramolecular aldol cyclization to furnish 2-acyl-3-halocyclohexanol with three controlled consecutive stereogenic centers. The reaction of bis-α,β-enones with the combination provides cyclic diketones with high stereoselectivity via an intramolecular Michael addition reaction.