Synthesis and Antibacterial Activity of Some New Phenothiazine Derivatives

A series of some new phenothiazine derivatives were synthesized with the objective for evaluation as antimicrobials. The title compounds were prepared by a five step synthesis scheme. 2‐Amino‐6‐substituted benzothiazoles (1) on diazotization afford 6‐substituted benzothiazolyl‐2‐diazonium chlorides (2). Reaction of 2 with cold solution of β‐naphthol in dilute NaOH furnishes α‐(2‐diazo‐6‐substituted benzothiazolyl)‐ β‐sodionaphthoxides (3) which on acidification with concentrated HCl gives α‐(2‐diazo‐6‐substituted benzothiazolyl)‐β‐naphthols (4). Reaction of 4 with p‐substituted anilines gives α‐(2‐diazo‐6‐substituted benzothiazolyl)‐β‐(p‐substituted anilino) naphthalenes (5). This synthesis besides by using conventional methods was also attempted using microwave. Fusion of 5 with sulphur in presence of iodine results in α‐(2‐diazo‐6‐substituted benzothiazolyl)‐6‐ substituted [2, 3‐b] benzophenothiazines(6). The structures of all these compounds have been supported by elemental analysis and their spectral studies. All synthesized compounds were tested for their antibacterial activity using standard drugs.