Sodium Hydroxide → 4-Amino-5-(cyclopentylmethoxy)-2-methylquinoline-3-carboxylic acid

Participants

Reaction Steps

To a solution of ethyl-4-amino-5-(cyclopentylmethoxy)-2-methylquinoline-3-carboxylate (Example 18a, 16.8 g, 51.2 mmol) in EtOH (100 mL) was added NaOH (2 N, 64 mL) at room temperature. The reaction mixture was refluxed for 4 h. After it was cooled down to room temperature, the reaction solution was filtered to remove any possible solid residue. The filtrate was carefully neutralized with 2N HCl to pH 7 at 0° C. The resultant precipitate was collected by filtration, washed with water, re-dissolved in EtOH (500 mL) and water (30 mL), and treated with activated charcoal (650 mg) at 70° C. for 0.5 h. The charcoal was removed by filtration, and the filtrate was concentrated and stored at 4° C. overnight. The resulting precipitate was collected by filtration, washed with cold 25% EtOH in H2O, and dried under vacuum at 60° C. overnight to give the title compound as an off-white solid (7.5 g, 49%). 1H NMR (400 MHz, DMSO-d6) δ 1.31-1.37 (m, 2H), 1.53-1.64 (m, 4H), 1.79-1.85 (m, 2H), 2.47-2.50 (m, 1H), 2.75 (s, 3H), 4.11 (d, J=8.8 Hz, 2H), 7.03 (d, J=8.0 Hz, 1H), 7.26 (d, J=8.4 Hz, 1H), 7.66 (t, J=8.0 Hz, 1H), 8.77 (brs, 1H), 12.26 (brs, 1H), 12.75 (brs, 1H). 1H NMR (400 MHz, CD3OD) δ 1.39-1.49 (m, 2H), 1.63-1.77 (m, 4H), 1.91-1.98 (m, 2H), 2.51-2.61 (m, 1H), 2.78 (s, 3H), 4.16 (d, J=8.0 Hz, 2H), 7.08 (d, J=8.0 Hz, 1H), 7.23 (d, J=8.0 Hz, 1H), 7.72 (t, J=8.0 Hz, 1H). MS 301 (MH+).

Provenance & Evidence