(3-Cyanopyridin-2-ylamino)-acetic acid ethyl ester → (3-Formylpyridin-2-ylamino)acetic acid ethyl ester

(3-Cyanopyridin-2-ylamino)acetic acid ethyl ester (2.6 g, 12.6 mmol) was dissolved into a 1:1:2 mixture of H2O/CH3COOH/pyridine (75 mL) under argon. Sodium hypophosphite (5.0 g) and Raney nickel (2.0 g) were added and the mixture was stirred at room temperature for 3 h. The slurry was filtered through a bed of celite and the filter cake was washed with water. Concentrated NH4OH was added to the filtrate until pH 10 was reached. The solution was extracted with ethyl acetate (4×50 mL). The organic phase was washed with brine (50 mL), dried over MgSO4 and concentrated. The product was purified by silica gel chromatography (CH2Cl2/EtOAc 9:1) to give the title compound as a clear yellow oil (2.16 g, 83%). 1H NMR (300 MHz, CDCl3) δ 9.86 (s, 1H), 8.69 (bs, 1H), 8.31 (dd, J=4.8, 1.9 Hz, 1H), 7.79 (dd, J=7.6, 2.0 Hz, 1H), 6.72 (dd, J=7.6, 4.8 Hz, 1H), 4.32 (d, J=5.5 Hz, 2H), 4.24 (q, J=7.0 Hz, 2H), 1.29 (t, J=7.2 Hz, 3H).