Oxidative sulfamidation and further heterocyclization of trivinyl and tetravinylsilanes

• Tetravinylsilane and methyl(trivinyl)silane were studied in the reactions with sulfonamides in oxidative conditions, varying the reagents, solvent and oxidant. • Chemoselective addition to only one C=C bond of the substrate is explained by the effect of electronegative atoms in the α- and β-positions in monoadducts. • The main course of the NBS-induced reaction with highly acidic triflamide and nosylamide is bromosulfonamidation with solvent interception (MeCN or THF) • No desilylation occurs in the studied reactions, although the processes of the Si–C were observed by us earlier. The NBS-induced bromosulfonamidation of methyl(trivinyl)silane and tetravinylsilane with sulfonamides was investigated in a hope to realize their supposedly high synthetic potential due to the presence of several C=C bonds. Unexpectedly, the reaction occurs at only one C=C bond, which is in striking contrast with the few previously studied reactions and was explained by the effect of electronegative atoms in the α- and β-positions in monoadducts, and even more important effect of α-branching, not observed in the earlier studied reactions. The main products with strongly acidic triflamide and nosylamide in MeCN or THF (apart from the side products of bromination) were the products of the solvent interception reaction, which were cyclized to the silylated 4,5-dihydro-1 H -imidazoles and 1,4-oxazocanes in high yield. No solvent interception occurred with less acidic arenesulfonamides, but only bromosulfonamidation of one C=C bond.