Acyl–oxygen fission in reactions of organosilicon carboxylates with sodium methoxide in methanol

Abstract

The compounds (Me₃Si)₃CSiMe₂O₂CR [R = Me, CH₂Cl, CF₃, Ph, C₆H₄NO₂-p, C₆H₃(NO₂)₂-3,5] and Bu^t₃SiO₂CCF₃, in which there is serious steric hindrance to nucleophilic attack at silicon, react with 0.20M-NaOMe in MeOH to give the corresponding silanols, (Me₃Si)₃CSiMe₃OH and Bu^t₂SiOH; i.e., exclusive acyl–oxygen fission occurs rather than the normal silicon–oxygen fission. With both trifluoroacetates the reaction is complete within ca. 1 min at room temperature. For the (Me₃Si)₃CSiMe₂O₂CR species the reactivity sequence is R = CF₃ > C₆H₃(NO₂)₂-3,5 > CH₂Cl > C₆H₄NO₂-p > Me > Ph.