Yield:251996-86-8 97%

Reaction Conditions:

Stage #1: methyl 4-chlorothieno[2,3-c]pyridine-2-carboxylatewith lithium hydroxide;water in tetrahydrofuran at 20; for 3 h;
Stage #2: with hydrogenchloride in tetrahydrofuran;water; pH=4;

Steps:

8

4-Chlorothieno[2,3-c]pyridine-2-carboxylic acid. Methyl 4- chlorothieno[2,3-c]pyridine-2-carboxylate (19.76 g) was dissolved in 100 mL THF and treated with 100 mL 2M LiOH at room temperature for 3 hours. The reaction mixture was acidified with concentrated HCl to pH = 4. A white solid (17.93 g, y = 97%) was obtained after filtration, washing with MeOH and air drying. LCMS (API-ES) m/z (%): 214.1 (100%, M⁺+H); ¹H NMR (300 MHz, CD₃OD) δ ppm 8.35 (s, 1H) 8.71 (s, 1H) 9.54 (s, 1H).

References:

WO2009/11871,2009,A2 Location in patent:Page/Page column 130; 131