Synthesis, characterization and biological evaluation of some heterocyclic compounds containing ethoxyphthalimide moiety <i style="">via</i> key intermediate 6-chloro 1,3 benzothiazole 2-amine

Abstract

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New and simple synthetic methods for the synthesis of ethyl 8-chloro-4(4-substitutedphenyl)-2-[(<i style="">N</i>-ethoxyphthalimido)amino]-4<i style="">H</i>-pyrimido[2,1-<i style="">b</i>][1,3] benzothiazole-3-carboxylate <b style="">5a-d</b> and 6-chloro-<i style="">N</i>-[3-{2-(4-substitutedphenyl)ethenyl}-1-<i style="">N</i>-ethoxy­ph­tha­li­midoquinoxalin-2(1<i style="">H</i>)-ylidene]-1,3-benzothiazol-2-amine <b style="">10a-d</b> are described. 4-Chloroaniline <b style="">1</b> is converted to 6-chloro-1,3-benzothiazol-2-amine <b style="">2</b> by reaction with KSCN and Br₂. Compound <b style="">2</b> acts as key intermediate for both the series of final compounds. In one pathway, <b style="">2</b> is converted to corresponding pyrimidothiazoles <b style="">4a-d</b> by treatment with ethyl arylidinecyanoacetate <b style="">3a-d</b>, which on condensation with phthalimidoxyethyl bromide <b style="">6</b> gives <b style="">5a-d</b>. In a parallel route, reaction of <b style="">2</b> with 3-[2-(4-substituted phenyl)ethenyl]quinoxalin-2(1<i style="">H</i>)-one <b style="">8a-d</b> affords 6-chloro-<i style="">N</i>-[3-{2-(4-substituted phenyl)ethenyl}quinoxalin-2(1<i style="">H</i>)-ylidene]-1,3-benzothiazol-2-amine <b style="">9a-d </b>which on condensation with phthalimidoxyethyl bromide <b style="">6</b>, yields final compound <b style="">10a-d</b>. Structure elucidation is accomplished by elemental analysis and spectral data of the synthesized compounds. Final compounds <b>5a-d</b> and <b>10a-d</b> have been screened <i>in vitro </i>for their antimicrobial activity against different strains of bacteria and fungi.

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