Photochemical oxidation of 4h-seleno(thio)pyrans

Oxidation of solutions of 4H-thiopyrans and 4H-selenopyrans to the corresponding heteroaromatic cation bromide occurs on irradiation with ultraviolet light in the presence of CBr₄. Reaction takes place by a free radical chain mechanism. The presence of CHBr₃ and C₂Br₆ in the reaction mixture was detected chromatographically.N. G. Chennyshevskii Saratov State University, Saratov 410026, Russia. Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 6, pp. 749–751, June, 1999.