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Synthesis and Structure of Ladder Oligosilsesquioxanes:  Tricyclic Ladder Oligomethylsilsesquioxanes

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posted on 06.11.2006, 00:00 by Ken-ichi Suyama, Takahiro Gunji, Koji Arimitsu, Yoshimoto Abe
Novel tricyclic ladder oligomethylsilsesquioxanes were prepared by heterofunctional condensation of cis-trans-cis-1,3,5,7-tetraisocyanato-1,3,5,7-tetramethylcyclotetrasiloxane with 1,3-di-tert-butoxy-1,3-dimethyldisiloxane-1,3-diol in the presence of triethylamine in THF. A mixture of stereoisomers of the tricyclic oligomethylsilsesquioxanes was obtained. Two of the isomers were separated as white solids by recycle-type high-performance liquid-phase chromatography. They were determined by X-ray crystallography to be tricyclic ladder oligomethylsilsesquioxanes consisting of three eight-membered rings arranged in syn- and anti-configurations.