4-METHYLBENZO(B)THIOPHENE-2-CARBOXYLICACID synthesis

Yield:1735-13-3 189 mg

Reaction Conditions:

with lithium hydroxide monohydrate in methanol;water at 80; for 2 h;

Steps:

12.2

A mixture of 203 mg of methyl 4-methylbenzo[b]thiophene-2-carboxylate, 50 mg of lithium hydroxide monohydrate,2 ml of water, and 6 ml of methanol was stirred for 2 hours at 80°C. The reaction mixture was concentrated underreduced pressure, water was added to the residues, and the residue was washed three times with tert-butyl methylether. Concentrated hydrochloric acid was added to the aqueous layer, and then extraction was performed for threetimes by using tert-butyl methyl ether. The collected organic layer was washed with saturated saline, dried over magnesiumsulfate, and then concentrated under reduced pressure, thereby obtaining 189 mg of 4-methylbenzo[b]thiophene-2-carboxylic acid (hereinafter, described as a "compound 20 of the present invention").1H-NMR (CDCl3) δ: 8.25 (s, 1H), 7.73-7.71 (m, 1H), 7.40-7.38 (m, 1H), 7.22-7.20 (m, 1H), 2.66 (s, 3H).

References:

EP2926660,2015,A1 Location in patent:Paragraph 0277; 0278