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Published online by Cambridge University Press: 17 March 2011
A series of structurally-defined laddersiloxanes [1] are presented. Pentacyclic laddersiloxanes were prepared by a stepwise procedure from all-cis-tetraisopropylcyclotetrasiloxanetetraol. All-anti pentacyclic, tetracyclic, tricyclic, and bicyclic laddersiloxanes were obtained by oxidation from respecting all-anti pentacyclic ladder polysilane. Stereocontrolled approach using RS-disiloxanediol as an expanding unit enabled the synthesis of longer laddersiloxanes. Finally, methyl-substituted ladder polysilsesquioxane was obtained by the stepwise transformation from (MePhSiO) 4. The X-ray crystal structures, NMR and IR spectra, and thermal stability of these laddersiloxanes are summarized.