Yield: 22%

Reaction Conditions:

Stage #1:quinazoline-6-carboxylic acid ethyl ester with sodium hydroxide in ethanol;water at 20; for 1 h;
Stage #2: with hydrogenchloride in ethanol;water; pH=4

Steps:

H.3
Preparation Example H-3. Quinazoline-6-carboxylic acid To a solution of quinazoline-6-carboxylic acid ethyl ester (79mg, 0.391 mmol) in ethanol (4mL) was added an aqueous solution of 1 N sodium hydroxide (4mL), and the solution was stirred for 1 hour at room temperature. 1 N Hydrochloric acid was added to the reaction mixture to adjust the pH to 4, and the solution was evaporated in vacuo. Ethanol was added to the residue, and the organic layer was concentrated. The residue was dissolved in an ethyl acetate-tetrahydrofuran mixture solvent, dried over anhydrous magnesium sulfate, then, evaporated in vacuo, and quinazoline-6-carboxylic acid (15mg, 0.086mmol, 22%) was obtained. This was used in the next reaction without purification. ¹H-NMR Spectrum (DMSO-d₆) δ (ppm): 8.09 (1 H, d, J=8.8Hz), 8.44 (1 H, dd, J=2.0, 8.8Hz), 8.83 (1 H, d, J=2.0Hz), 9.39 (1 H, s), 9.79 (1 H, s).

References:

Eisai R&D Management Co., Ltd. EP1782811, 2007, A1 Location in patent:Page/Page column 58-59