Use of piperidine-1-sulphenyl chloride as a sulphur-transfer reagent in reactions with diamines: the preparation of sulphur–nitrogen heterocycles

The use of piperidine-1-sulphenyl chloride (3) as a sulphur-transfer reagent in reactions with diamines is described. The reaction of (3) with o-phenylenediamine yielded the dihydro-2,1,3-benzothiadiazole (6) and benzothiadiazole (7). Oxidation of (6) with m-chloroperoxybenzoic acid yielded (7). The reactions of (3) with 1,8-diaminonaphthalene and 1,4,5,8-tetra-aminonaphthalene yielded the 1,2,6-thiadiazine derivatives (14) and (16); possible mechanisms are discussed. 1,2-Diamino-N,N′-dimethylethane and (3) yielded the tetrahydrothiadiazole (17), whereas 1,3-diaminopropane and (3) afforded the novel N–S–N chain compound (19). The reactions of morpholine-1-sulphenyl chloride (4) with aromatic diamines gave the same products in low yields.