Chemistry of Epoxyquinols A, B, and C and Epoxytwinol A

The asymmetric total synthesis of epoxyquinols A, B, and C and epoxytwinol A, and computational analysis of the key biomimetic oxidative dimerization procedure are described. In the first‐generation synthesis, a HfCl 4 ‐mediated diastereoselective Diels–Alder reaction of furan with Corey's chiral auxiliary has been developed. In the second‐generation synthesis, a chromatography‐free preparation of an iodolactone using acryloyl chloride as the dienophile in the Diels–Alder reaction of furan and a lipase‐mediated kinetic resolution of a cyclohexenol derivative have been developed. This second‐generation synthesis is suitable for large‐scale synthesis. A biomimetic cascade reaction involving oxidation, 6π‐electrocyclization, and then Diels–Alder dimerization is the key reaction in the formation of the complex heptacyclic structure of epoxyquinols A, B, and C. Epoxytwinol A is synthesized by the cascade reaction involving oxidation, 6π‐electrocyclization, and formal [4+4] cycloaddition reactions. A 2 H ‐pyran, generated by oxidation/6π‐electrocyclization, acts as a good diene, reacting with several dienophiles to afford polycyclic compounds in one step. (© Wiley‐VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2007)