In a recently published article2 it was shown that butadiene, 2, 3-dimethylbutadiene and cyclopentadiene undergo an essentially quantitative addition to dibenzoylethylene with formation of dibenzoylcyclohexenes (I). Syntheses from these adducts were developed for the corresponding dibromo addition products (II), dihydroisobenzofurans (V), isobenzofurans (IV), o-dibenzoylbenzeiies (VI), oxido-tetrahydronaphthalenes (VII) and ...