Stereoselective synthesis of different cyclic tetrasiloxane isomers depending on the superacid catalyst employed

Abstract

In this study, we investigated the hydrolytic condensation of 3-aminopropyldiethoxymethylsilane over different superacid catalysts. We found that cyclic tetrasiloxanes with different stereostructures (Am-CyTS-NNf₂ and Am-CyTS-NHf₂) could be selectively prepared in high yields (>95%) depending on the superacid catalyst employed (bis(nonafluorobutanesulfonyl)imide or cyclohexafluoropropane-1,3-bis(sulfonyl)imide). The single-crystal X-ray structural analyses of compounds in which amino groups of Am-CyTS-NNf₂ and Am-CyTS-NHf₂ were protected by the tert-butoxycarbonyl group revealed the formation of all-cis and cis–trans–cis cyclic tetrasiloxanes, respectively.