Synthesis of fused 1,2,4-thiadiazolines by intramolecular cycloaddition-elimination reactions of 4-methyl-5-(cyano tethered)imino-Δ2-1,2,3,4-thiatriazolines

Article abstract of DOI:10.1016/S0040-4020(01)90364-3

A series of 5-imino-1,2,3,4-thiatriazolines, bearing a cyano tether at the imine function, were prepared and converted into fused 1,2,4-thiadiazole derivatives by thermolysis; these are 12a→13, 20a→21, 20b→22 and 29→30 (Schemes 2-5). In one case, the precursor thiatriazole also underwent an intramolecular cycloaddition-elimination reaction to give a fused 1,2,4-thiadiazole; namely 17a→18. Thiatriazoline 33, with an aryl group attached directly to the imine function, thermolyzed to the benzothiazole 34.