Heteroorganic betaines 3.~* Reactions of betaines containing the ~+P-C-Si-S~- fragment

摘要

The [Ph_3P~+-CMe_2-SEt]Br~- salt was prepared by the reaction of betaine Ph_3P~+-CMe_2SiMeR-S~-(1a: R = Me) with EtBr. Acetylation of betaine la or Et-3P~+-CHMeSiMe_2-S~- (2a) afforded 2,2,6-trimethyl-1,3-dioxa-2-silacyclohex-5-ene-4-thione Me_2SiOC(=S)CH=C(Me)O or the [Et_3P~+-CHMeSiMe_2Cl]Cl~- salt depending on the reagent ratio. The reactions of betaines la, b (1b:R - Ph) or 2 with compounds (R_3Sn)_2X (X = O or NMe)can be used for the generation of silanones[RMeSi=O]and silaneimines[RMeSi = NMe]in solutions. The reactivity of betaines Ph_3P~+-CHR~1SiMeR~2-S~-(R~1 = H)or Me and R~2 = Me or Ph) is determined by the equilibrium between the zwiterionic and ylide Ph_3P=CR~1MeR~2SH tautomers that exist in solutions