7-Bromobenzo[b]thiophene-2-carboxylic acid

The second step in the preparation of methyl 7-bromo-benzo [b] thiophene-2- carboxylate 64 mg (0.22 mmol) was dissolved in a 3 ml of methanol and then, 3N sodium hydroxide, 240 ul (0.72 mmol) was added 2 hours and heated to reflux. The reaction mixture was acidified with 3N hydrochloric acid and extracted with ethyl acetate 30 ml. It was charged and the organic dried and concentrated under reduced pressure over anhydrous sodium sulfate (Na2SO4). To give the 62 mg yield as a white solid target compound without a residue purified by silica gel column chromatography 100percent (0.24 mmol).General procedure: The solution of compound 2a or 2b (1.1 mmol) in water (10 mL)was stirred and then potassium hydroxide pellets (5.4 mmol) wasadded, which was refluxed for 3 h. The aqueous layer was thenacidified to pH 1 with 1 M hydrochloric acid solution. The aqueouslayer was extracted with dichloromethane (3 15 mL). The combinedorganic layers were dried with sodium sulfate, filtered, andthe solvents were removed under reduced pressure to afford thetitle compound 3a or 3b.A mixture of 300 mg of methyl 7-bromobenzo[b]thiophene-2-carboxylate, 100 mg of lithium hydroxide monohydrate, 3 ml of water, and 9 ml of methanol was stirred for 2 hours at 75°C. The reaction mixture was concentratedunder reduced pressure. Water was added to the residues, and the residue was washed three times with tert-butylmethyl ether. Concentrated hydrochloric acid was added to the aqueous layer, and then extraction was performed 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 272 mg of 7-bromobenzo[b]thiophene-2-carboxylic acid (hereinafter, described as a 'compound 13 of the present invention'). 1H-NMR (DMSO-D6) δ: 13.74 (br s, 1H), 8.27 (s, 1H), 8.06 (dd, 1H, J = 7.8, 0.9 Hz), 7.78 (dd, 1H, J = 7.8, 0.9 Hz), 7.44(t, 1H, J = 7.8 Hz).

Molecular Weight:257.11
XLogP3:3.5
Hydrogen Bond Donor Count:1
Hydrogen Bond Acceptor Count:3
Rotatable Bond Count:1
Exact Mass:255.91936
Monoisotopic Mass:255.91936
Topological Polar Surface Area:65.5
Heavy Atom Count:13
Complexity:222
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes