Silanetriols as Powerful Starting Materials for SelectiveCondensation to Bulky POSS Cages

摘要

Controlled condensation reactions of tertiary silanetriols CH3(CH2)n(CH3)2CSi(OH)3 (>1b–>f; n = 1–5) in the presence of trifluoroacetic acid and the hydrolysis of CH3(CH2)6(CH3)2CSiCl3 (>3) lead to the selective formation of the corresponding disiloxane tetrols [CH3(CH2)n(CH3)₂CSi(OH)₂]₂O (>2b–>g; n = 1–6) in good yields. The TBAF-driven condensation reactions of the silanetriols CH₃(CH₂)_n(CH₃)₂CSi(OH)₃ (>1a–>c; n = 0–2) as well as of the disiloxane-1,1,3,3-tetrol >2d (n = 3) yield in the selective formation of the first T₈ cages bearing tertiary carbon substituents, CH₃(CH₂)_n(CH₃)₂C (>4a–>d; n = 0–3), which was not possible via the condensation of their alkoxysilane counterparts so far. The resulting compounds >2b–>g and >4a–>d have been characterized by multinuclear NMR, MS, and single-crystal X-ray diffraction.