Introduction of Functional Silyl Groups into Tris(dialkylamino)phosphonium Methylides

Starting from tris(dialkylamino)phosphonium methylides (R₂N)₃PCH₂ [1a: R = Me; 1b: R = Et] a series of silylated ylides with functional groups at the silicon substituents have been prepared (2 - 8). In the general formula X₃Si-CH=P(NR₂)₃ the group SiX₃ represents examples for X = Me, Cl, Br, OMe, iPrO, NMe₂, but also for X₃ = PhH₂ etc. The compounds are prepared either via the transylidation reaction of 1a, b with reaction components X₃SiY [Y = Cl, OTf], or through action of a base on the corresponding silylated phosphonium salts, following methods of preparation for non-functional silylated ylides. Bis(ylides) (9 - 12) are available along the same sequence of reactions, but employing difunctional silanes X₂SiY₂. Products of the type X₂Si[CH=P(NR₂)₃]₂ were investigated with X = Me, OMe, OEt, and NMe₂. All ylides are thermally stable, distillable liquids, which have been identified via conventional spectroscopic methods. The ylides are versatile synthons in trans-silylation, trans-ylidation, and de-silylation reactions.