The question of C- vs. O-silylation of ketenes: electrophilic triethylsilylation of diphenylketene.

Prakash, G K Surya; Bae, Chulsung; Rasul, Golam; Olah, George A · Proc Natl Acad Sci U S A · 2005

basic_science · Level V

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Abstract

Electrophilic triethylsilylation of diphenylketene leads to exclusive C-silylation giving the diphenyl(triethylsilyl)acetyl cation in the solution phase even though density functional theory calculations at the B3LYP/6-311+G* level indicate that the O-silylation of diphenylketene is preferred over C-silylation by 5.4 kcal/mol in the gas phase. On the other hand, in the case of the parent ketene, similar density functional theory calculations show that C-silylation is preferred over O-silylation by 8.2 kcal/mol.