Synthesis and biological evaluation of 1-(6-methylpyridin-2-yl)-5-(quinoxalin-6-yl)-1,2,3-triazoles as transforming growth factor-β type 1 receptor kinase inhibitors.

A series of 1-(6-methylpyridin-2-yl)-5-(quinoxalin-6-yl)-1,2,3-triazoles has been synthesized and evaluated for their ALK5 inhibitory activity. The 1-(6-methylpyridin-2-yl)-1,2,3-triazoles were assembled by Cu(I)-catalyzed azide-alkyne 1,3-dipolar cycloaddition. Following this, quinoxaline was introduced through Pd-catalyzed direct arylation. The synthesized 1-(6-methylpyridin-2-yl)-5-(quinoxalin-6-yl)-1,2,3-triazoles revealed significant selectivity differences with respect to p38α MAP kinase. In particular, 12k showed 80.8% ALK5 inhibitory activity at a concentration of 10 μM and IC(50) value of 4.69 μM, but did not show p38α MAP kinase inhibitory activity (-1.94% inhibition at a concentration of 10 μM).