The Reaction of Highly Hindered Silicon Halides with Nucleophiles

Abstract

(Me₃Si)₃CSi(CD₃)₂I, (Me₃Si)₃CSi(CD₃)₂Br, and (Me₃Si)₃CSi(CD₃)₂H solvolyze in refluxing acetic acid in the presence of HgX₂ to give, in addition to (Me₃Si)₃CSi(CD₃)₂X and (Me₃Si)₃CSi(CD₃)₂OAc, isomers with structures (Me₃Si)₂C(SiMe₂X)Si(CD₃)₂Me and (Me₃Si)₂C(SiMe₂OAc)Si(CD₃)₂Me. The first two also react if AgX is used in place of HgX₂, but (Me₃Si)₃CSi(CD₃)₂H is inert. In refluxing trifluoroacetic acid (Me₃Si)₃CSi(CD₃)₂I and (Me₃Si)₃CSi(CD₃)₂H solvolyze even in the absence of a catalyst to give similar products. The products distributions are believed to arise from nucleophilic attack on a methyl-bridged cationic intermediate.