Geometry optimizations were carried out using the B3PW91/6311G(d), B3LYP-D/6-311G(d), and MP2/6-31G(d) methods. Initial structure for intermediate C gave compound 2 (by B3LYP-D/6
- M. Anpo, C. Chatgilialoglu, K.U.J. Org. Chem. Ingold
Bicyclic dihydrothiophenes are readily prepared by a radical cascade cyclization reaction triggered by the addition of a thiyl radical under thermal or photoirradiation conditions. The translocated radical attacks the sulfur atom in the initial radical donor unit in an SHi manner. Sufficient stereoselectivity is achieved when a large excess of disulfide is used for the reaction under photoirradiation conditions. The reaction in the absence of solvents provides vinylsulfides instead of dihydrothiophenes. Thus, the sulfur atom in the thiyl radical serves as a sulfur biradical synthetic equivalent.