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

A convenient and scalable (gram-scale) route to unprecedented T 8 D 2 -double-decker siloxanes (DDSQs) bearing four chloro ( 3b ) or four azido ( 5b ) groups is reported. Both compounds were characterized and proved to undergo successful nucleophilic substitution for 3b (with iodide or azide) and copper-catalyzed azide-alkyne [3 + 2] cycloaddition for 5b . 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 D 2 T 8 structures, the reported tetrafunctional DDSQs are formed as a single isomer and readily isolated in very high yields. Moreover, the tetra-azido DDSQ 5b 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.