Lithiation/silylation of ethyl 2-alkyl-1-trimethylsilylcycloprop-2-ene-1-carboxylate. Experimental and computational study

Abstract

The formation of novel trimethylsilyl-substituted allenes, including silyl ketene acetals incorporating an allenic moiety, by lithiation/silylation of ethyl 2-alkyl-1-trimethylsilylcycloprop-2-ene-1-carboxylate, is described. The reaction involves formation of silyl ketene acetal 3 (3a) which upon aqueous work-up gives diastereomeric allenes 4′ (4′a) and 4″ (4″a). Becke3LYP/6-311+G** calculations were also carried out to provide geometries, energies and insights into the electronic structure of the proposed reaction intermediates.