2,3,5,6,7,8-Hexasilabicyclo[2.2.2]octane-1-carboxylic acids and esters: preparation and structure

Polysilacage acid HC(SiMe2SiMe2)3CCO2H was prepared quantitatively by deprotonation of HC(SiMe2SiMe2)3CH by a superbase in excess followed by trapping with CO2. The acid allowed to disclose X-ray analysis of hydrogen-bonded dimers that preferred pairs of the same enantiomeric isomers. Cage diacid HO2CC(SiMe2SiMe2)3CCO2H also was prepared. Esterification of the acids was found to proceed in good yields via the Mitsunobu conditions using diisopropyl azodicarboxylate.