Metathetical cyclization of dienes: tolerance and behavior of a cyclometallated aryloxycarbene complex of tungsten towards diallylic compounds

Intramolecular metathesis of various diallylic compounds containing the O, S, Si or P hetero-elements was achieved in good yields by using the cyclometallated carbene complex W(OAr)(OAr)(CHCMe₃)Cl(OEt₂). Unsubstituted diallyl ether is converted into 2,5-dihydrofuran; diallyl sulfide is converted into 2,5-dihydrothiophen; diallylphenyl phosphine is converted into 1-phenyl-2,5-dihydro-1H-phosphole; and diallyldimethyl- or diphenylsilanes are converted into the corresponding silacyclopentenes. The metathesis reaction of methyl-substituted diallyl sulfides shows that steric effects are very important. Depending on the position of the methyl groups, the reaction can proceed normally or be completely inhibited.