To a solution of 1-(2-cyclopropyl-3-methylimidazo[1,2-a]pyridin-6-yl)-4-hydroxypyridin-2(1H)-one (350 mg), (5-(difluoromethyl)-2-thienyl)methanol (409 mg) and tributylphosphine (755 mg) in THF (12 ml) was added 1,1′-(azodicarbonyl)dipiperidine (942 mg), and the reaction mixture was stirred at 60° C. for 3 h. The reaction mixture was cooled to room temperature, concentrated and purified by silica gel column chromatography (hexane/EtOAc then MeOH/EtOAc). The resulting solid was recrystallized from EtOH-hexane to give the title compound (80 mg) as a white solid.
