Phenyl and Diaryl Ureas with Thiazolo[5,4-d]pyrimidine Scaffold as Angiogenesis Inhibitors: Design, Synthesis and Biological Evaluation.

Angiogenesis is crucial for tumor growth and inhibition of angiogenesis has been regarded as a promising approach for cancer therapy. Vascular endothelial growth factor receptor-2 (VEGFR-2) is an important factor in angiogenesis. In this work, a novel series of thiazolo[5,4-d]pyrimidine derivatives inhibiting angiogenesis were rationally designed and synthesized. Their inhibitory activities against human umbilical vein endothelial cells (HUVEC) were investigated in vitro. 1-(4-Fluorophenyl)-3-{4-[(5-methyl-2-phenyl[1,3]thiazolo[5,4-d]pyrimidin-7-yl)amino]phenyl}urea (19b) and 1-(3-Fluorophenyl)-3-{4-[(5-methyl-2-phenyl[1,3]thiazolo[5,4-d]pyrimidin-7-yl)amino]phenyl}urea (19g) exhibited the most potent inhibitory effect on HUVEC proliferation (IC50 =12.8 and 5.3 µm, respectively). Compound 19g could inhibit the migration of human umbilical vein endothelial cells. These results support the further investigation of these compounds as potent anticancer agents.