The synthesis and reactions of 2,11-diselena[3,3]metacyclophanes. An investigation of the selenoxide elimination route to metacyclophane-1,8-dienes

2,11-Diselena[3,3]metacyclophane and its 9,18-dimethyl derivative are prepared in ca. 7% yield from Na2Se and xylylene bromide. Wittig rearrangement and benzyne induced Stevens rearrangement gave the ring contracted [2,2]metacyclophane derivative. Attempted selenoxide elimination to produce metacyclophane-diene failed. The 1Hmr spectra of the selenametacyclophane indicate that the syn-conformer is the more stable. A general synthesis of aryl-alkenes in an 80% yield starting from benzyl phenyl selenide, alkylation with an alkyl halide, and then selenoxide elimination is given.