Synthesis and biological evaluation of sulfonylhydrazone-substituted imidazo[1,2-a]pyridines as novel PI3 kinase p110α inhibitors

We have previously reported the imidazo[1,2-a]pyridine derivative 4 as a novel p110α inhibitor; however, although 4 is a potent inhibitor of p110α enzymatic activity and tumor cell proliferation in vitro, it is unstable in solution and ineffective in vivo. To increase stability the pyrazole of 4 was replaced with a hydrazone and a moderately potent p110α inhibitor 7a was obtained. Subsequent optimization of 7a afforded exceptionally potent p110α inhibitors, including 8c and 8h, with IC50 values of 0.30 nM and 0.26 nM, respectively; to the best of our knowledge, these compounds are the most potent PI3K p110α inhibitors reported to date. Compound 8c was also stable in solution and exhibited significant anti-tumor effectiveness in vivo.

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