Lead tetraacetate oxidation of the Diels-Alder adduct of 7-dehydrocholestryl acetate with maleic anhydride

Abstract

The Diels-Alder adduct (3), obtained by cycloaddition of 7-dehydrocholesteryl acetate (1) and maleic anhydride (2), was heated at ca. 90?C with a large excess of lead tetraacetate in pyridine solution for 5h. Under these conditions, compound 3 underwent lactonization with the participation of the olefinic ?6-double bond to give two isomeric monolactone derivatives, 9 and 10 (in a total yield of ca. 6%), and the bislactone product 11 (in 11.5% yield). The starting material was recovered in 36% yield.