A new route to 1,3,4-thiadiazolines. Part 3. Consequences of the aza-enamine concept

Abstract

N,N-Disubstituted hydrazones react with sulphenyl chlorides, sulphur dichloride, and disulphur dichloride to give C-sulphenyl products. N,N-Tetramethylenehydrazones with SCl₂ or S₂Cl₂ give the novel pyrrolo[2,1-b]-1,3,4-thiadiazole ring system. Studies of the site selectivity in reaction of these hydrazones with sulphur(II) electrophiles by the semiempirical CNDO and MNDO methods are reported.