Selenobenzophenones and Diazoalkanes: Isolation of Tetraarylethylenes by the Reaction of Benzophenone Hydrazones with Diselenium Dibromide

The reaction of selenobenzophenones with diazomethane afforded the corresponding diarylethylenes and symmetrical olefins. The reaction with diaryldiazomethanes gave three different types of tetraarylethylenes. This reaction proceeded through 1,3,4-selenadiazoline intermediates, and retrocyclization was observed. The formation of 1,3,4-selendiazolines was independently confirmed by the reaction of benzophenone hydrazones with diselenium dibromide, which afforded tetraarylethylenes in good yields. This method is applicable to the two-step synthesis of tetraarylethylenes from benzophenones. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2004)