Preparation and reactions of difunctional sterically hindered organosilicon compounds of the type (Me3Si)2C(SiMe2X)(SiMe2Y)
Abstract
Reaction of TsiSiMelCl [Tsi =(Me3Si)3C] with AgY or AgBF4 gave the rearranged species R2C(SiMe2Cl)(SiMe2Y)(Y = OSO2CF3, OCIO3, OCOCF3, OSO2C6H4Me-p, or F)(R = Me3Si throughout). Correspondingly, TsiSiMelF reacted with AgSO3CF3 to give R2C(SiMe2F)(SiMe2OSO2CF3) and with ICI to give R2C(SiMe2F)(SiMe2Cl); TsiSiMelBr likewise gave R2C(SiMe2Br)(SiMe2OSO2CF3) on treatment with AgSO3CF3 but the di-iodide TsiSiMel2 reacted even with 1 molar equiv. of various silver salts to give R2C(SiMe2Y)2(Y = F, OCIO3, OSO2CF3 or OSO2C2H4Me-p) along with unchanged TsiSiMel2. The iodo-hydride TsiSiMeHl gave only unrearranged TsiSiMeHF when treated with AgBF4 in Et2O, but a mixture of R2C(SiMe2H)(SiMe2F), TsiSiMeHF, and R2C(SiMe2F)2 when CH2Cl2 was used as solvent. Other R2C(SiMe2X)(SiMe2Y) species were made as follows; (i) with X = H; Y = Cl, Br, or I, along with R2C(SiMe2X)2, from R2C(SiMe2H)2 with 1 molar equiv. of X2; (ii) R2C(SiMe2X)2(X = Br or I) from R2C(SiMe2H)2 and 2 molar equiv. of X2; (iii) with X = F, Y = I, from R2C(SiMe2F)(SiMe2H) and I2; (iv) with X = OMe, Y = Cl, from R2C(Cl)(SiMe2OMe)[via R2C(Li)(SiMe2OMe)] and Me2SiCl2.
The methanolyses of several R2C(SiMe2X)(SiMe2Y) species were examined, and the results are discussed in terms of anchimeric assistance by the X or Y groups.