O-(2,2,2-Trifluoroethyl)hydroxylamine hydrochloride → 6-[(E)-3-[3-[(Z)-C-methyl-N-(2,2,2-trifluoroethoxy)carbonimidoyl]azetidin-1-yl]-3-oxoprop-1-enyl]-3,4-dihydro-1H-1,8-naphthyridin-2-one

2,2,2-Trifluoroethoxyamine hydrochloride (37 mg, 0.24 mmol) was added to a solution of (E)-6-(3-(3-acetylazetidin-1-yl)-3-oxoprop-1-enyl)-3,4-dihydro-1,8-naphthyridin-2(1H)-one (50 mg, 0.16 mmol) in methanol (4 mL). The reaction mixture was stirred at room temperature for 3 hours. After concentration to dryness the residue was diluted by addition of dichloromethane (50 mL) and saturated sodium bicarbonate solution (10 mL). The aqueous phase was extracted with dichloromethane (2×40 mL). The combined organic phases were washed with a saturated solution of sodium chloride (1×20 mL), dried over sodium sulfate, filtered and concentrated to dryness. The residue was purified by chromatography on silica gel using ethyl acetate/methanol (95:5) as eluent to obtain the title product as a white solid (47 mg, 50%).