Ethyl 4-oxo-1,4-dihydrocinnoline-3-carboxylate → 4-Oxo-1,4,5,6,7,8-hexahydrocinnoline-3-carboxylic acid ethyl ester

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Reaction Steps

To 4-oxo-1,4-dihydrocinnoline-3-carboxylic acid ethyl ester (4.5 g) dissolved in trifluoroacetic acid (20 ml) was added platinum oxide (0.2 g). The reaction mixture was hydrogenated at 50 psi until no further uptake of hydrogen was observed. The catalyst was collected by filtration, the filtrate was poured onto ice, the pH was raised to pH6 with base, the resulting precipitate was collected by filtration, washed with water and dried to give a solid (2.8 g, 61%). δH (250 MHz; DMSO-d6) 1.26 (3H, t, J=7 Hz, CH3), 1.68 (4H, m, CH2), 2.33 (2H, t, J=5.5 Hz, CH2), 2.62 (2H, t, J=5.5 Hz, CH2), 4.25 (2H, t, J=7 Hz, CH2), 13.19 (1H, br s, NH), m/z (ESP+) 223 (MH+).

Provenance & Evidence