4-Acetoxycyclopent-2-enone : a synthetic equivalent for cyclopentadienone in Diels-Alder reactions

Abstract The Lewis acid catalyzed Diels-Alder reactions of 4-acetoxycyclopentenone 5 with both cyclic and acyclic dienes is described. Subsequent base induced elimination of the β-acetoxy group from the respective cycloadducts leads to bi- and tricyclic enones in good yields. The ν-facial diastereoselectivity of the cycloaddition of 5 with cyclopentadiene is 3:1, in favor of the anti-adduct 6a .