Synthesis and characterization of four process impurities in pazopanib

Pazopanib (trade name Votrient®) is a potent and selective multi-targeted tyrosine kinase inhibitor that blocks tumor growth and inhibits angiogenesis. Based on a recently reported procedure, we herein report the first synthesis of four potential process impurities generated in the production of pazopanib. The structure of these impurities were synthesized and characterized by 1H NMR, 13C NMR and HRMS data. The possible formation mechanisms of these impurities were also elucidated. These findings should be useful for the quality control of pazopanib in manufacture.