Generation and reactivities of ethylmethoxysilylene

Article abstract of DOI:10.1016/S0022-328X(97)00144-7

Vacuum pyrolysis of 1,2-diethyl-1,1,2,2-tetramethoxydisilane (II) in the presence of 2,3-dimethyl-1,3-butadiene resulted in the formation of 1-ethyl-1-methoxy-(III), 1-ethyl-(IV), and 1-methoxy-3,4-dimethyl-1-silacyclopent-3-ene(V) along with ethyltrimethoxysilane. The observed products might be formed from the addition of ethylmethoxysilylene, ethylsilylene and methoxysilylene into 2,3-dimethyl-1,3-butadiene respectively under thermal conditions. A labelling experiment employing a deuterated precursor of 1,2-diethyl-1,1,2,2-tetramethoxy-d₁₂-disilane (II-d₁₂) was performed for the purpose of elucidating the conversion of ethylmethoxysilylene into ethylsilylene. Ethylsilylene might be generated from [3 → 2 + 1] cyclo-elimination of an intermediate of 2-ethyloxasilacyclopropane (EtHSi-O-CH₂) which can arise from a possible intramolecular silylene insertion into a C-H bond of the methoxy group of ethylmethoxysilylene. The methoxysilylene might be formed from elimination of ethylene of 1-methoxy-1-silacyclopropane (HMeOSi-CH₂-CH₂) derived from intramolecular silylene insertion into a C-H bond of the ethyl group of ethylmethoxysilylene. The temperature dependence of the trapped adduct distribution from the pyrolysis of 1,2-diethyl,1,2,2-tetramethoxydisilane was examined.