5-{8-[(3,4'- difluoro [1,1'- biphenyl]-4-yl) methoxy] - 2-methylimidazo [1,2-a] pyridin-3-yl}-n-methylpyridin-2-formamide (1o) showed high potency in vitro and brain exposure, inducing brain a β 42 levels were significantly reduced and showed undetectable inhibition of cytochrome P450 enzymes. In addition, compound 1o showed excellent anti cognitive deficit effect in AD model mice.