Bromination of intermediate 1-[4-(6, 7-dihydro-5H-cyclopenta [4, 5] thieno[2, 3-d]pyrimidin-4-yl amino) phenyl] ethanone (4) yielded (5). Which upon reaction with different substituted benzothiazoles give a novel series of pyrimidine [6(a-g)]. However reaction of (5) with 4-chloro-2-triflouro acetyl aniline provided (6h). Similarly reaction of (5) with 5-amino tetrazole & 2-amino benzimidazole produced (6i) & (6j) respectively. All the synthesized compounds were tested against bacteria (Gram positive and Gram negative).