3′-(1-Methyl-3-nitro-2-oxo-1,2-dihydropyridin-4-ylamino)biphenyl-2-carbonitrile (0.11 g, 0.32 mmol) was suspended in ethyl acetate (10 ml) and ethanol (10 ml), platinum oxide (7.3 mg, 0.03 mmol) added and the mixture hydrogenated at 45 psi on a Parr hydrogenator for 2 h. The catalyst was filtered off through a glass fibre filter paper and the filtrate evaporated to give 3′-(3-amino-1-methyl-2-oxo-1,2-dihydropyridin-4-ylamino)biphenyl-2-carbonitrile as an orange oil. The oil was dissolved in formic acid (4 ml) and heated at 95° C. for 24 h. The mixture was allowed to cool to ambient temperature and evaporated. The residue was made basic by the addition of concentrated ammonia solution, then diluted with water (100 ml) and extracted with dichloromethane (2×100 ml). The combined organic layer was washed with brine (50 ml), dried over anhydrous sodium sulfate, filtered and evaporated to give a brown oil. The oil was purified by flash column chromatography on silica eluting with dichloromethane (+1% concentrated ammonia) on a gradient of methanol (2-4%). Collecting appropriate fractions, followed by trituration with diethyl ether (5 ml), gave 3′-(5-methyl-4-oxo-4,5-dihydroimidazo[4,5-c]pyridin-1-yl)biphenyl-2-carbonitrile (64 mg, 61%) as a white solid: δH (400 MHz, CDCl3) 3.69 (3H, s), 6.66 (1H, d, J 7), 7.24 (2H, m), 7.52-7.58 (2H, m), 7.65-7.67 (2H, m), 7.69-7.74 (2H, m), 7.84 (1H, dd, J 8 and 1), 7.99 (1H, s); m/z (ES+) 327 (M++H).
