“…76 The thermal fragmentation of 1,4,2-dithiazines in the presence of dienophiles aimed at the synthesis of 1,4-dithyines has been studied. 74 It was found that 1,4,2-dithiazine derivatives 68 react with dimethyl acetylenedicarboxylate (20) on heating in o-dichlorobenzene to give a mixture of dimethyl 4,5-dimethylthiophene-2,3-dicarboxylate (69) and 3-(4-bromophenyl)-4,5-dimethylisothiazole (70). The latter is formed upon thermolysis of dithiazine 68 and is accompanied by a loss of the sulfur atom from position 4.…”