Study of Fragmentation Reactions of Highly Sterically Hindered Organosilicon Compounds with Alcoholic Sodium Alkoxides

The compounds (Me₃Si)₃CSiXX′X^″ [X = Me, X′ = (C₆H₄Me-p), X^″ = I; X = Et, X′ = X^″ = Cl; X = Bu, X′ = X^″ = Cl)] reacted with boiling RONa/ROH [R = Pr, iso-Pr, Bu, Et, Benzyl, iso-Amyl] to give the fragmentation products of the type (Me₃Si)₂CHSiXX′(OR) and Me₃SiCH₂SiXX′(OR) [X = Me, X′ = (C₆H₄Me-p] or (Me₃Si)₂CHSiX(OR)₂ [X = Et or Bu]. Study of the products showed that alkoxides as nucleophile cannot attack the silicon center bearing the (Me₃Si)₃C- group because of steric hindrance. It is suggested that the reaction proceeds through an elimination, analogous to the E2 elimination of alkyl halides, involving the synchronous attack of RO⁻ at a Me₃Si group, the liberation of X⁻, and the formation of (Me₃Si)₂C═SiXX′.

Keywords:

• Alkoxide
• fragmentation
• organosilicon
• trisyl