Synthesis of Tetrachloro, Tetraiodo, and Tetraazido Double-Decker Siloxanes.

A convenient and scalable (gram-scale) route to unprecedented TD-double-decker siloxanes (DDSQs) bearing four chloro () or four azido () groups is reported. Both compounds were characterized and proved to undergo successful nucleophilic substitution for (with iodide or azide) and copper-catalyzed azide-alkyne [3 + 2] cycloaddition for . All of these transformations occurred under mild conditions, and the corresponding DDSQs were prepared in very high yields. Beyond the enhanced multivalency as compared to the previously described disubstituted DT structures, the reported tetrafunctional DDSQs are formed as a single isomer and readily isolated in very high yields. Moreover, the tetra-azido DDSQ constitutes a multipurpose nanobuilding block for the further preparation of new inorganic-organic hybrid materials where the covalent incorporation of a DDSQ moiety brings valuable properties.