[WBr2(CO)2(diene)]/AlCl2Et mixtures promote metathesis of cis-2-pentene to give 2-butene and 3-hexene. For diene = norbornadiene the reaction is catalytic, and is accompanied by cis to trans isomerisation of the 2-pentene, whereas for diene = 1,5-cyclooctadiene or cyclooctatetraene the metathesis is essentially stoicheiometric. The same complexes catalyze the metathesis of trans-2-pentene to give 2-butene and 3-hexene, but at approximately twice the rate observed for the cis-alkene. [WBr2(CO)2(diene)]/AlCl2Et mixtures also catalyse the metathesis of 1,7-octadiene to give cyclohexene and ethene. The intermediacy of metal carbene derivatives in such reactions is supported by the reactions of [WBr2(CO)2(norbornadiene)] with alkylating agents SiMe4 and MeMgBr which give methane, whereas [WBr2(CO)2(norbornadiene)] and AlCl2Et in the absence of alkenes gave virtually stoicheiometric amounts of ethane. © 1989.
|Number of pages||6|
|Journal||Journal of Organometallic Chemistry|
|Publication status||Published - 1 Aug 1989|