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 oC with a large excess of lead tetraacetate in pyridine solution for 5 h. Under these conditions, compound 3 underwent lactonization with the participation of the olefinic D6 -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.

Dils-Alderov adukt 3, dobiven cikloadicijom 7-dehidroholesteril-acetata 1 i anhidrida maleinske kiseline 2, oksidovan je velikim viškom olovotetraacetata u piridinskom rastvoru na oko 90 ºC u toku 5h. Pod navedenim uslovima izvršena je oksidativna laktonizacija jedinjenja 3 sa participacijom olefinske D6 -dvogube veze pri čemu su dobivena dva izomerna monolaktonska derivata 9 i 10 (u ukupnm prinosu od oko 6%) i bislaktonski proizvod 11 (u prinosu od oko 11,5%); pri tome je nepromenjen polazni adukt izolovan u prinosu od »36%.