Synthesis, Structural Study and Antimicrobial Screening of Substituted Bis-benzothiazole Derivatives

A series of {4-(4-(6-substituted-benzothiazol-2-yl-amino)-3-carboxy-benzyl)-2-carboxy- phenyl}-6-substituted-benzothiazol-2-yl-amines have been synthesized by oxidative cyclization of 1-{4-(4-(3-aryl thiocarbamido)-3-carboxy-benzyl)-2-carboxy-phenyl}-3-aryl thiocarbamides using the solution of bromine in chloroform followed by the basification with dilute ammonium hydroxide solution. Initially 1-{4-(4-(3-aryl thiocarbamido)-3-carboxy-benzyl)-2-carboxy-phenyl}-3-aryl thio- carbamides were prepared by the interaction of different aryl isothiocyanates with 4,4'-methylene- bis-(anthranilic acid). The latter was obtained by treating the mixture of anthranilic acid and concentrated hydrochloric acid with 3% aqueous formaldehyde followed by neutralization with sodium hydroxide. The acetylation of bis-benzothiazoles afforded di-acetyl derivatives. The structures of synthesized compounds have been established on the basis of chemical transformation, elemental analysis, equivalent weight determination and IR, 1 H NMR spectral studies. The title compounds have been assayed for their biological activity against gram-positive as well as gram- negative microorganisms.