Silaheterocycles. 32. Facile Synthesis of 3-Alkoxy-1-silacyclobutanes from the Trichlorovinylsilane/t-BuLi Reagent and Vinyl Ethers^†

Equimolar mixtures of trichlorovinylsilane and t-BuLi (1) were reacted with different vinyl ethers, CH₂CH−OR (R = Et, n-Pr, n-Bu, i-Bu, t-Bu), to yield the silacyclobutanes 2−6. NMR spectroscopic investigations showed the addition of the formal silene unit Cl₂SiCHCH₂t-Bu to the vinyl group of the vinyl ethers to be stereo- and regiospecific, forming products of E-configuration. In contrast, in the presence of bisvinyl [CH₂CH−O−(CH₂)_n−O−CHCH₂ (n = 2, 4, 6)] or cyclic vinyl ethers, such as 2,3-dihydrofuran and 3,4-dihydro-2H-pyran, the formation of silacylobutanes was suppressed and the formation of addition and SiCl/CHLi coupling products, such as Cl₂(R)SiCH₂CH₂t-Bu (RCl, 7; t-Bu, 8) and the tetrachloro-1,3-disilacyclobutane, (Cl₂SiCHCH₂t-Bu)₂ (10), was favored. Compounds 8 and 10 were characterized by single-crystal X-ray diffraction studies.