ChemInform Abstract: Formation of Thioaldehyde Intermediates by Thermolysis of Sulfoxides Bearing Some Heteroaromatics

Thermal reactions of phenacyl sulfoxide bearing heterocycles, such as a 2-benzothiazolyl or N-oxypyridyl group, in the presence of 2,3-dimethyl-1,3-butadiene afforded 6-benzoyl-5,6-dihydro-3,4-dimethyl-2H-thiapyran in good yield. This product is considered to be formed by the Diels−Alder reaction of a diene with thioaldehyde formed initially by the decomposition of sulfoxides.