SYNTHESIS (IN ENT-FORM) OF A NOVEL JALCAGUAIANOLIDE FROM FERULA-ARRIGONII BOCCHIERI

A recently isolated isodehydrocostus lactone from the genus Ferula (Umbelliferae) has been stereoselectively prepared in ent-form from alpha-santonin by photochemical transformation to O-acetylisophotosantonic lactone followed by functional group manipulations that conclude with a one-step gamma-butyrolactone --> Delta(alpha,beta)-butenolide conversion; the synthesis corroborates both the structure and the relative and absolute stereochemistry that have been proposed for the natural product.