Catalytic Intramolecular Crossed Aldehyde−Ketone Benzoin Reactions: A Novel Synthesis of Functionalized Preanthraquinones

Stereochemically and functionally rich polycyclic compounds are obtained by the first crossed aldehyde−ketone benzoin reaction in excellent yield under mild reaction conditions (5−20 mol % thiazolium salt, 10−70 mol % DBU, tBuOH, 40 °C, 30 min). This novel catalytic methodology offers a convenient approach to sophisticated molecular architectures useful for the stereocontrolled construction of polycyclic compounds as well as the fully regiocontrolled synthesis of anthra- and naphthoquinones.