1-Methyl-1H-1,2,3-benzotriazole-5-carboxylic acid

1-Methyl-1,2,3-benzotriazole-5-carboxylic acid is an organic intermediate that can be prepared from 4-amino-3-nitrobenzoic acid as a raw material. 4-amino-3-nitrobenzoic acid is then prepared, followed by methylation to obtain methyl 4-methylamino-3-nitrobenzoate, reduction of the nitro group to obtain methyl 4-methylamino-3-aminobenzoate, cyclization to obtain methyl 4-methylamino-3-aminobenzoate, and finally hydrolysis of the methyl ester to obtain 1-methyl-1,2,3-benzotriazole-5-carboxylic acid.

The synthesis of 1-Methyl-1H-1,2,3-benzotriazole-5-carboxylic acid is carried out as follows:
To a stirred suspension of the diamine 280 (1.08g; 6.48mmol) (or any other oarylenediamine) in water (25 mL) at 0°C, concentrated HCl (5.4 mL) was added drop wise followed by slow addition of a solution of NaNO2 (643mg; 9.3mmol) in water (10 mL). The reaction mixture was stirred at 0°C for 2h and then was allowed to warm up to 10°C over 4h; neutralized with a solution of KOH (5.6 g) in water (30mL) (final pH = 6); concentrated and purified by preparative HPLC in reverse phase mode (column aquasil C-18, elution 5% to 95% MeOH in water), to afford the title compound 284 (211 mg; 18% yield). 1-Methyl-1H-benzo[d][1,2,3]triazole-5-carboxylic acid (284), yield (211 mg; 18%). 1HNMR: (400.2 MHz, DMSO) δ (ppm): 8.35 (s; 1H); 8.08 (dd, J= 1.4, 8.6 Hz; 1H); 7.75 (d, J= 1.4 Hz; 1H); 4.03 (s, 3H). MS: calc: 177.1; found: 178.1 (M+H).