Under nitrogen protection, 4-(3-ethoxy-3-oxoprop-1-enyl)-3-nitrobenzoic acid (45) (29 g, 0.11 mol) was dissolved in 75 mL of methanol and 10% Pd-C (100 mg) was added. The mixture was subjected to a 50 psi H2 atmosphere for 12 hours of reaction. Upon completion of the reaction, the reaction mixture was filtered through a sintered funnel and the filtrate was concentrated to afford pure 2-oxo-1,2,3,4-tetrahydroquinoline-7-carboxylic acid (22) as an off-white solid (20.9 g, 96% yield).1H NMR (400 MHz, CDCl3): δ 2.44 (t, J=6.8 Hz, 2H); 2.90 (t, J=6.8 Hz 2H); 7.25 (d, J=7.6Hz, 1H); 7.44 (s, 1H); 7.47 (dd, J=7.6,1.6Hz, 1H); 10.22 (br s, 1H); 12.85 (br s, 1H).13C NMR (75MHz, CDCl3): δ24.8,30.0,115.1,123.5, 127.8,127.9,129.0,139.0,167.5,169.0.
