Recently the synthesis of fused heterocyclic compounds possessing pyrimidothiazine as central core has been interested for researchers because of possesing various biological properties such as antibacterial [1], antiallergic, anti-inflammatory [2], phosphodiesterase inhibition and antiparkinsonism [3]. From the chemical points of view, several methods for the synthesis of various derivatives of pyrimidothiazine have also been reported in the literature [4]. In this study, we synthesized a series of new derivatives of 7,8-dihydro-6Hbenzo[b]pyrimido[5,4-e][1,4]thiazine through the reaction of (1) and (2) in refluxing ethanol which was subsequently treated with POCl and various secondary amines, respectively. The anti proliferative activities of these compounds are also evaluated. 3

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