Oxidative sulfamidation of vinyl silanes: A route to diverse silylated N-Heterocycles

Crystal structure and Hirshfeld surface analysis of N-{[diphen-yl(vin-yl)sil-yl]meth-yl}-2-methyl-propan-2-ammonium chloride

N-{[Diphen-yl(vin-yl)sil-yl]meth-yl}-2-methyl-propan-2-amine, C19H25NSi, is a newly synthesized secondary amino-methyl-silane that can be used, for example, to study carboli-thia-tion reactions of vinyl-silanes. Because the neutral compound did not crystallize well, the hydro-chloride salt, C19H26NSi+·Cl-, was formed, in which the two chloride ions in the asymmetric unit have crystallographic site symmetry. An unusually long Si-C bond of 1.9117 (10) Å is observed in the cation, which may be ascribed to electronic effects due to the β N+ species. In the crystal, the cations and anions are linked by N-H⋯Cl hydrogen bonds to generate [001] chains. To further investigate the inter-molecular inter-actions, a Hirshfeld surface analysis was performed, which showed that H⋯H, C⋯H/H⋯C and H⋯Cl/Cl⋯H contacts contribute 70.4, 20.0 and 8.3%, respectively.

Divergent reactivity of divinylsilanes toward sulfonamides in different oxidative systems

Oxidative sulfonamidation of divinylsilanes with various sulfonamides in different solvents is reported. With t-BuOI as an oxidant, halogenation is the main process, whereas aziridines are the minor products. With NBS in CH₂Cl₂ the products of bromination or bromosulfonamidation were obtained, whereas in MeCN or THF the Ritter-type solvent interception products are formed. The obtained bromosulfonamidation products undergo base-induced cyclization to various heterocycles, including imidazolines, 1,4-oxazocanes, or Si,N-containing heterocycles of a new type, 1,3,5-diazasilinanes, in up to quantitative yield.

Trifluoromethanesulfonamide vs. Non-Fluorinated Sulfonamides in Oxidative Sulfamidation of the C=C Bond: An In Silico Study

A theoretical analysis of the reaction of oxidative sulfamidation of several alkenes was performed in order to explain the various experimental observations and different reactivity of triflamide and non-fluorinated sulfonamides. Transformations occurring in the system alkene–sulfonamide in the presence of oxidative system (Bu^tOCl + NaI) were analyzed at the MP2/DGDZVP//B3LYP/DGDZVP level of theory using the IEF-PCM method for taking into account the solvent acetonitrile (MeCN) effect. As the model substrates, styrene, trimethyl(vinyl)silane, dimethyl(divinyl)silane and diphenyl(divinyl)silane were chosen and mesylamide, triflamide, tosylamide and p-nosylamide were taken as the reagents. Bu^tOI generated from Bu^tOCl and NaI reacts with sulfonamides to give N-iodinated sulfonamides RSO₂NHI and RSO₂NI₂ as active intermediates, the iodinating activity of the latter being notably higher. The analysis allowed to answer such challenging questions as different reactivity of nonfluorinated sulfonamides leading to aziridination and of triflamide resulting in the formation the main products of bis-triflamidation, or different regioselectivity of halogenation of styrene and trimethyl(vinyl)silane caused by a linear intermediate iodonium cation in the former case and a cyclic one in the latter.

Solvent interception, heterocyclization and desilylation upon NBS-induced sulfamidation of trimethyl(vinyl)silane

The reaction of trimethyl(vinyl)silane with sulfonamides in the presence of N-bromosuccinimide was shown to proceed regioselectively in methylene chloride under mild conditions and led to the products of bromosulfamidation in up to 88% yield. The obtained adducts undergo base-promoted dehydrobromination to give 2-trimethylsilyl-N-sulfonyl aziridines in a close to quantitative yield. In the reaction with trifluoromethanesulfonamide in acetonitrile or tetrahydrofuran, the Ritter-type (solvent-interception) products were obtained and converted to 1-triflyl-2-methyl-5-(trimethylsilyl)-2-imidazoline or 4-triflyl-3-(trimethylsilyl)-1,4-oxazocane in almost quantitative yield.