To a suspension of 400 mg of 8-(cyclohexylmethoxy)-2-methyl-N-[(3S)-pyrrolidin-3-yl]imidazo[1,2-a]pyridine-3-carboxamide dihydrochloride, 0.26 ml of triethylamine, and 0.23 ml of a 37% aqueous formaldehyde solution in 11 ml of dichloroethane was added 592 mg of sodium triacetoxyborohydride under ice-cooling, followed by stirring at room temperature for 1 hour. To the reaction mixture were added a saturated aqueous sodium hydrogen carbonate solution and chloroform to carry out a layer separation operation. The organic layer was dried over anhydrous sodium sulfate and the solvent was evaporated under reduced pressure. The obtained residue was purified by silica gel column chromatography to obtain 249 mg of 8-(cyclohexylmethoxy)-2-methyl-N-[(3S)-1-methylpyrrolidin-3-yl]imidazo[1,2-a]pyridine-3-carboxamide.
