Synthesis and Biological Activity of 2-Amino-4H-pyrimido[2,1-b][1,3]benzothiazole-3-carboxylates

Abstract

3-Chloro-4-fluoro aniline (1) on reaction with potassium thiocyanate (2) followed by the addition of bromine in acetic acid medium yielded 2-amino 5-chloro-6-fluro[2,1-b][1,3]benzothiazole (3). Compound 3 when treated with b-cyanoester undergoes cycloaddition reaction to produce 2-amino-4H-pyrimido[2,1-b][1,3]benzothiazole. Analogous cycloaddition reaction occurs on refluxing 3 with arylidene b-cyanoesters (6a-j) in sodium ethoxide and absolute ethanol. The resulting compounds were identified as ethanol 2-amino-4H-pyrimido[2,1,-b][1,3]benzothiazole- 3-carboxylates (7a-j). The arylidenes 6a-j were conveniently prepared by adopting Knoevenagel method. The newly synthesized compounds were characterized by physical constant, elemental analysis and spectral data. The compounds were then evaluated for antibacterial, antifungal and anthelmintic activities.