[Synthesis]
A reaction mixture was prepared in toluene (40 mL) using 4-(ethoxycarbonyl)pyridine-1-oxide (3.64 g, 21.82 mmol), dimethylformamide dimethyl acetal (3.01 mL, 32.73 mmol) and zinc cyanide (3.84 g, 32.73 mmol). The mixture was heated to reflux for 2 h under argon protection. After the reaction was completed, it was cooled to room temperature, water (30 mL) was added and stirring was continued for 15 minutes. The organic layer was separated, washed with brine, dried over anhydrous magnesium sulfate and concentrated under reduced pressure to give a brown solid. Subsequently, purification by silica gel column chromatography using ethyl acetate:petroleum ether (2:1, v/v) as eluent afforded a yellow oil which solidified to an orange solid (3.28 g, 85% yield) in an ice bath. The melting point of the product was 39-40 °C (literature value 42-44 °C). Infrared spectrum (KBr) νmax: 2988, 2964, 2238, 1728, 1597, 1557, 1470, 1402, 1393, 1370, 1298, 1281, 1202, 1113, 1015, 990, 918, 890, 862, 763, 686 cm-1. NMR Hydrogen Spectroscopy (300 MHz , CDCl3) δ: 8.90 (1H, dd, J=4.9, 0.9 Hz, pyridine-H), 8.25 (1H, dd, J=1.5, 0.9 Hz, pyridine-H), 8.10 (1H, dd, J=4.9, 1.5 Hz, pyridine-H), 4.47 (2H, q, J=7.1 Hz, OCH2), 1.44 (3H, t, J=7.1 Hz, OCH2), 1.44 (3H, t J=7.1 Hz, CH3). NMR carbon spectrum (75 MHz, CDCl3) δ: 163.1 (C=O), 151.9, 139.0, 134.7, 127.6, 126.1, 116.6 (CN), 62.6 (OCH2), 14.1 (CH3). High resolution mass spectrometry (ESI): [M+H]+ measured value 177.0659, C9H9N2O2 calculated value 177.0659.The NMR data are in agreement with literature reports. |