Synthetic studies on the heterocyclic nucleus of the cytochalasans

Abstract

A synthetic route is described to a tricyclic lactone-lactam (10), the gross structure of which represents a logical type of intermediate for a synthetic approach to the cytochalasans. The required stereochemistry was built into the starting material (5) by a Diels–Alder reaction involving interaction of maleic anhydride and (E,E)-4-methylhexa-2,4-dienol. However, an unexpected double epimerisation took place in the elaboration process leading from (5) to (10).