Silanetriols as Powerful Starting Materials for Selective Condensation to Bulky POSS Cages

[Image: see text] Controlled condensation reactions of tertiary silanetriols CH(3)(CH(2))(n)(CH(3))(2)CSi(OH)(3) (1b–f; n = 1–5) in the presence of trifluoroacetic acid and the hydrolysis of CH(3)(CH(2))(6)(CH(3))(2)CSiCl(3) (3) lead to the selective formation of the corresponding disiloxane tetrols [CH(3)(CH(2))(n)(CH(3))(2)CSi(OH)(2)](2)O (2b–g; n = 1–6) in good yields. The TBAF-driven condensation reactions of the silanetriols CH(3)(CH(2))(n)(CH(3))(2)CSi(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 T(8) cages bearing tertiary carbon substituents, CH(3)(CH(2))(n)(CH(3))(2)C (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.