Isatin → 3-Methyl-2-phenylquinoline-4-carboxylic acid

Participants

Reaction Steps

A solution of isatin (5.00 g, 34.0 mmol), propiophenone (5.47 g, 5.43 mL, 40.8 mmol), and potassium hydroxide pellets (6.73 g, 102 mmol) in ethanol (40 mL) was stirred at reflux for 23 h. After cooling, the solvent was removed in vacuo to give a brown residue. The residue was dissolved in water (75 mL) and washed with diethyl ether (4×100 mL). The aqueous layer was cooled by the addition of ice (˜50 g) and acidified to pH˜1 via dropwise addition of concentrated HCl with stirring. A solid precipitate was collected by filtration, washed with water and dried to provide the title compound as a yellowish-tan solid (7.59 g, 85%), which was used without further purification. MS (API+): M+1: 264 (45%), 220 (100); %); 1H NMR (300 MHz, DMSO-d6) d 2.39 (s, 3H), 7.49-7.57 (m, 3H), 7.59-7.72 (m, 7.76-7.84 (m, 2H), 8.06 (d, J=8.5 Hz, 1H), 14.20 (v br s, 1H, exchangeable).

Provenance & Evidence