Novel benzothiazole containing 4H-pyrimido[2,1-b]benzothiazoles derivatives: One pot, solvent-free microwave assisted synthesis and their biological evaluation

Abstract

Synthesis of new and desired compounds has an everlasting demand. The present work emphasizes on the one pot, three component microwave assisted synthesis of novel ethyl 2-methyl-4-(pyridin-2-yl)-4H-benzo[4,5]thiazolo[3,2-a]pyrimidine-3-carboxylate derivatives by the reaction of 2-aminobenzothiazole derivatives with Pyridine 2-aldehyde and Ethyl acetoacetate in the presence of PdCl2 as an expeditious catalyst under solvent-free condition. The salient features of this approach are operational simplicity, convergence, short reaction time, high atom economy, easy workup, mild reaction conditions and environmentally benign conditions. All the newly synthesized diverse poly-functionalized tri-heterocyclic benzothiazole derivatives have been characterized by elemental analysis and various spectroscopic methods such as FT-IR, 1H NMR, 13C NMR, ESI-MS and Single crystal X-ray analysis (4a). All the final scaffolds have been screened for antibacterial and antioxidant activities. Also their antitubercular activity against Mycobacterium tuberculosis H37RV was screened. Keywords: Antioxidant, 2-Amino benzothiazole, Microwave irradiation, 4H-pyrimido[2,1-b]benzothiazoles, Solvent-free reaction, Mycobacterium tuberculosis