反应详情

1,4-Dihydro-2,6-dimethyl-4-(3-nitrophenyl)-3,5-pyrazinedi-carboxylic acid, dimethyl ester (219 mg, 0.63 mmol) was dissolved in 30 mL methanol containing 3 mL of water in a flask equipped with a mechanical stirrer. Iron powder (300 mg) was added, followed by one drop of 37% hydrochloric acid. The whole mixture was refluxed moderately with mechanical stirring for 3.5 hours. Usual extractive work up furnished the title compound as yellow solid (176 mg, 88%): mp 212-213° C.; 1H-NMR (CDCl3) δ 6.91 (t, 1H, J=8.0 Hz), 6.20 (dd, 1H, J=7.8, 2.0 Hz), 6.11 (dd, 1H, J=8.2, 2.3 Hz), 6.00 (t, 1H, J=2.2 Hz), 5.93 (s, 1H), 3.77 (s, 6H), and 2.38 (s, 6H); 13C-NMR (CDCl3) δ 166.8, 152.0, 148.5, 146.9, 129.6, 109.5, 107.8, 104.2, 100.3, 51.8, and 17.9.

1. customequipped with a mechanical stirrer
2. temperatureThe whole mixture was refluxed moderately