M. Al-abdalla, Mukesh Jain, R. Gupta
1995
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0
Influential Citations
2
Citations
Journal
Heterocyclic Communications
Abstract
Synthesis of title compounds by Smiles rearrangement has been repor ted . 2-Amino-5-phenoxybenzenethiol was condensed with o-halonitrobenzenes to prepare diphenyl sulphides, which on formylation with 90% formic acid and subsequent treatment with alcoholic potassium hydroxide underwent Smiles rearrangement yielding 7-phenoxyphenothiazines. Nitrophenothiazines have been prepared by the condensation of 2-amino-5-phenoxybenzenethiol with halonitrobenzenes containing a nitro group or one nitro group and other halogen atom at both ortho positions to the reactive halogen atom as Smiles rearrangement occurs in situ. Introduction Phenothiazines are well known for their pharmacological and biological activities and their several derivatives are in clinical use (1,2). A slight alteration in the substitution pattern in phenothiazine nucleus causes a marked difference in the biological activities. Recently a great interest has arisen to synthesize phenothiazines to screen anticancer activities (3-12). Therefore it is considered worthwhile to synthesize unknown phenothiazines in search of better medicinal agent. Results and Discussion 7-Phenoxyphenothiazines 6a-g have been prepared by Smiles rearrangement of 5-phenoxy-2-formamido-2-nitrodiphenyl sulphides 5 in alcoholic potassium hydroxide solution. The formyl derivatives were prepared by the formylation of resultant diphenyl sulphides 4 obtained by the condensation of 2-amino-5-phenoxybenzenethiol 1 with o-haloni trobenzenes 2 in ethanolic sodium acetate solution (Scheme 1). 2-Amino-5-phenoxybenzenethiol 1 required in the synthesis of title compounds has been prepared by the alkaline hydrolytic cleavage of 2-amino-6-phenoxybenzothiazole adopting the method reported elsewhere (13,14). Ni t rophenothiaz ines have been prepared by the condensat ion of 2-amino-5phenoxybenzenethiol 1 with o-halonitrobenzenes 3 containing nitro group or one nitro and