A metal–amide dependent, catalytic C–H functionalisation of triphenylphosphonium methylide

We report the [Y{N(SiMe3)2}3] catalysed dehydrocoupling of triphenylphosphonium methylide with phenylsilane to form the silylated ylide Ph3PCHSiH2Ph. Attempts to catalyse this reaction with the related group 2 hexamethyldisilazide base [Ca{N(SiMe3)2}2] led to the catalytic formation of the phosphine Ph2PCHSiH2Ph along with Ph2PMe in low selectivity, while group 1 bases [M{N(SiMe3)2}] (M = Li, Na, K) proved ineffective for both transformations. The stoichiometric reactions of Ph3PCH2 with [M{N(SiMe3)2}n] have been investigated and allowed the isolation and characterisation of a cyclometallated phosphonium methylide complex of yttrium.