Synthesis of 4-Silacyclohexan-1-ones and (4-Silacyclohexan-1-yl)amines Containing the Silicon Protecting Groups MOP (4-Methoxyphenyl), DMOP (2,4-Dimethoxyphenyl), or TMOP (2,4,6-Trimethoxyphenyl): Versatile Si- and C-Functional Building Blocks for Synthesis

Abstract

The 4-silacyclohexanones 1–6 were prepared in convenient multistep syntheses, starting from MeSi(OMe)3 and PhSi(OMe)3, respectively. Cleavage of the 4-methoxyphenyl (MOP), 2,6-dimethoxyphenyl (DMOP), and 2,4,6-trimethoxyphenyl (TMOP) protecting groups of 4–6 by treatment with HCl/Et2O in CH2Cl2 at 20 °C gives the 4-chloro-4-silacyclohexanone 13. Reductive amination of 1–6 with NH3 or i-PrNH2 yields the respective (4-silacyclohexan-1-yl)amines 7–12. Compounds 1–12 and all new precursors synthesized were characterized by elemental analyses (C, H, N) or mass spectrometric investigations (ESI-HRMS) and by NMR spectroscopic studies (1H, 13C, 29Si). Compounds 1, 3, 5, and 6 and the precursors (MeO)2SiPh(TMOP) (21) and (CH2═CH)2SiPh(TMOP) (27) were additionally characterized by single-crystal X-ray diffraction. Compounds 1–12 with their Si- and C-functional groups represent versatile building blocks for synthesis.