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)

Selenobenzophenones react with diazomethanes to afford the corresponding diarylethylenes and symmetrical tetraarylethylenes. The reaction proceeds via 1,3,4-selenadiazoline intermediates which undergo retrocyclization. This is confirmed by isolation of three different types of tetraarylethylenes from diaryldiazomethanes and by formation of tetraarylethylenes from the reaction of benzophenone hydrazones with Se 2 Br 2 . -(OKUMA*, K.; KOJIMA, K.; OYAMA, K.; KUBO, K.; SHIOJI, K.; Eur. J. Org.