Si- and C-Functional Organosilicon Building Blocks for Synthesis Based on 4-Silacyclohexan-1-ones Containing the Silicon Protecting Groups MOP (4-Methoxyphenyl), DMOP (2,6-Dimethoxyphenyl), or TMOP (2,4,6-Trimethoxyphenyl)

4-Silacyclohexan-1-ones 1a–1c, 4-silacyclohexan-1-one oximes 2a–2c, 1,4-azasilepan-7-ones 3a–3c, 1,4-azasilepanes 4a–4c, and 2-bromo-4-silacyclohexan-1-ones 5a and 5b were prepared in multistep syntheses, starting from trimethoxypropylsilane. All of these compounds represent C-functional (R2C═O, R2C═N–OH, R–NH(C═O)–R, R2NH, or R3C–Br) silicon-containing heterocycles that contain Si–MOP, Si–DMOP, or Si–TMOP moieties (MOP = 4-methoxyphenyl; DMOP = 2,6-dimethoxyphenyl; TMOP = 2,4,6-trimethoxyphenyl), which can be cleaved under mild conditions by protodesilylation. As a proof of principle, compounds 3a–3c were transformed quantitatively and selectively into the chlorosilane 6 (treatment with hydrogen chloride in dichloromethane). Thus, the C- and Si-functional compounds 1a–1c, 2a–2c, 3a–3c, 4a–4c, 5a, and 5b represent versatile building blocks for synthesis.