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

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