7521-41-7

105-53-3

5174-90-3

General procedure for the synthesis of ethyl 2-oxo-1,2-dihydro-[1,8]naphthyridine-3-carboxylate from 2-amino-3-pyridinecarboxaldehyde and diethyl malonate: 2-amino-3-pyridinecarboxaldehyde (1.0 g, 8.19 mmol) was suspended in a screw-capped pressure tube containing diethyl malonate (6.2 mL, 41.0 mmol). The reaction tube was sealed by the addition of piperidine (1.6 mL, 16.4 mmol). The reaction mixture was heated to 120°C and the reaction was kept at a constant temperature for 3.0 hours. Upon completion of the reaction, the mixture was allowed to cool to room temperature. The precipitate formed was collected by filtration and washed with ether (Et2O) to afford ethyl 2-oxo-1,2-dihydro-[1,8]naphthyridine-3-carboxylate 1.62 g in 91% yield. The structure of the product was confirmed by 1H NMR (CD3OD): δ 8.64 (m, 1H), 8.62 (s, 1H), 8.22 (m, 1H), 7.32 (m, 1H), 4.38 (m, 2H), 1.40 (t, 3H).