Silica Gel-promoted Synthesis of 1,4-Oxa-thiane Derivatives from b,b'-Dichloro Sulfides

Treatment of bis(2-chloro-2-phenylethyl) sulfide, prepared from SC12 and styrene, with commercially available silica gel in n-hexane and benzene at 30 "C for 6 h gave 2,6-diphenyl-l A-oxathiane in quantitative yield.The cyclization was successfully applied to other P,P'-dichloro sulfides, affording 1,4-oxathiane derivatives.Sulfur dichloride ( X I 2 ) has long been known as a potential enophilic reagent which easily forms bis(2chloroalkyl) sulfides upon addition to olefins.'In the course of our studies on this compound, we discovered that it is a facile sulfur transfer reagent in the preparation of sulfurcontaining heterocycles from nitriles2 and imines.3The high reactivity of SClz toward unsaturated bonds has often been utilized in the synthesis of cyclic sulfides from diolefinic compounds.'We previously reported the synthesis of sulfurcontaining bicyclic P-lactams by the treatment of diolefinic p-lactams with SCI2.4Although a considerable