SYNTHESIS OF 7-HYDROXYPHTHALIDES STARTING FROM UNSATURATED LACTONES VIA 2-TRIALKYLSILOXYFURANS

Abstract

Abstract Diels–Alder adducts of maleic anhydride and 2-trialkylsiloxy furans, prepared from unsaturated lactones and trialkylchlorosilane in high yields, afforded 3-hydroxyphthalic anhydrides on treatment with hydrobromic acid. The anhydrides were regiospecifically reduced to 7-hydroxyphthalides in high yields by means of excess sodium borohydride in alcohol.