A Simple Synthesis of 1-Acyl-3-aryl-3H-pyrrolo[2′,3′:4,5]pyrimido[6,1-b]benzothiazol-6-ium-2-olates: Betainic Derivatives of a Novel Heterocyclic System

Abstract

The title compounds were obtained by acylation of 5-amino-1-aryl-4-(2-benzothiazolyl)-2,3-dihydro-2-pyrrolones with 3-fold excess of acid chlorides. Starting pyrrolones were prepared in high yields by alkylation of 2-benzothiazoleacetonitrile with chloroacetic acid anilides. An X-ray crystallographic study of 1-benzoyl-3,5-diphenyl-3H-pyrrolo[2′,3′:4,5]pyrimido[6,1-b]benzo­thiazole-6-ium-2-olate was carried out to confirm the structure of title compounds unambiguously. The charge distribution in the obtained betaines was discussed.