6-Methoxy-3-methyl-benzo[b]thiophene-2-carboxylic acid synthesis

Yield:-

Reaction Conditions:

with methanol;sodium hydroxide;water at 60; for 18 h;

Steps:

146

A solution of methyl 3-methyl-6-(methyloxy)-1-benzothiophene-2-carboxylate in MeOH (500 mL) was treated with 2M sodium hydroxide (60 mL) and stirred at 60°C for 18 hours. The solvent was evaporated, the residue was taken up in water (600 mL) and the pH was adjusted to 1 by adding 2M HCI. A precipitate was formed. This was isolated by filtration, washed with 2M HCI and dried under reduced pressure, at 50°C for 3 days. After triturating with DCM, the pure title compound was obtained as a light brown solid (4.47 g).'H NMR (400 MHz, DMSO- d6) Q : 13.5-12. 9 (1H), 7.82 (1H, d, J 8.9 Hz), 7. 55 (1H, d, J 2.3 Hz), 7.07 (1H, dd, J 8.9, 2.3 Hz), 3.84 (3H, s), 2.66 (3H, s).

References:

WO2005/77926,2005,A2 Location in patent:Page/Page column 68-69