Organosilane-induced synthesis and functionalization of sulfur-containing compounds

Reactions of organothiosilanes with organic substrates generally lead to de livery of a sulfur moiety onto the target molecule, the precise outcome bei ng related to the structure of the silyl sulfide used. Aromatic and aliphat ic silyl sulfides react with carbonyl compounds under acidic or basic condi tions to afford thioacetals and thioketals, but reactions with more activat ed compounds such as alpha,beta-unsaturated acylsilanes give the Michael ad ducts, which represent versatile intermediates in organic synthesis. Silyl sulfides tan also participate in substitution reactions of silyl enol ether s to afford vinyl sulfides. On the contrary, hexamethyldisilathiane reacts with various carbonyl compounds under the catalysis of CoCl2. 6H(2)O or CF3 SO3SiMe3 with thionation of the carbonyl unit, thereby providing a general access to thioketones and thioaldehydes, which can be trapped in situ by di enes. The use of CF3SO3SiMe3 in the reaction with cyclohexadiene gives rise to the interesting feature that stereopredetennined access to either the e ndo or the exo isomer can be obtained. Furthermore, when using aromatic or heteroaromatic o-azidoaldehydes, the reactivity of hexamethyldisilathiane m ay be finely tuned to drive the reaction towards the synthesis of o-azidoth ioaldehydes, fused isothiazole ring systems, or aromatic and heteroaromatic o-amino aldehydes and o-amino thioaldehydes, Lastly, by taking advantage o f the high reactivity of the C-Sf bond under fluoride ion catalysis, select ive regiospecific thiophilic functionalizations of thioketones, dithioester s, trithiocarbonates, and their sulfines by various organosilanes such as a llylsilanes, benzylsilane, and alpha-hetero-substituted silyl nucleophiles can be realized.