Synthetic studies on some new diaryl sulphides and diaryl sulphones with fused heterocyclic rings

The reaction of 2-amino-6-[(p-nitrophenyl)thio]benzothiazole (1) with a variety of reagents namely chloroacetyl chloride, chloropropionyl chloride, p-toluenesulphonyl chloride, phenyl isothiocyanate, phenacyl bromides hasbeen carried out and their products were identified. Some of these products underwent ring closure reaction to afford fused tricyclic compounds. Compound 1 undergoes ring opening upon boiling with NaOH solution to give 2-amino-3-mercapto-4'-nitro diphenyl sulphide (2). Reaction of (2) with aromatic aldehydes, phenyl isothiocyanate, formic acid, carbon disulphide afforded the corresponding benzothiazole derivatives, while its reaction with chloroacetyl chloride or chloropropionyl chloride gave benzothiazine and benzothiazepine. All products were oxidized into the corresponding sulphones upon treatment with H 2 O/AcOH mixture.