Methyl 2-amino-1H-benzimidazole-6-carboxylate

AA. 5-Carboxylic acid-2-aminobenzimidazole (16) 5-Carboxylic acid methyl ester-2-aminobenzimidazole (350 mg, 1.83 mmol, 1.0 eq, 15) was dissolved in a 1:1 mixture of MeOH (10 mL) and water (10 mL) in a 100 mL round bottom flask, and treated with 5.0 M aq. NaOH (10 mL). The reaction mixture was stirred for 12 h at rt, after which the MeOH was removed in vacuo. The aqueous solution was cooled to 0 C., and concentrated aq. HCl was added until pH '2 was reached. The resulting precipitate was filtered and dried in vacuo at 50 C. to afford the HCl salt of 5-carboxylic acid-2-aminobenzimidazole (16) as a light brown crystalline solid (356 mg, 1.67 mmol, 91% yield). 1H NMR (300 MHz, DMSO-d6) delta 7.45 (d, 1H, J=8.3 Hz), 7.81 (dd, 1H, J=8.4, 1.5 Hz), 7.92 (d, 1H, J=1.4 Hz), 8.90 (s, 2H), 12.99 (bs, 2H); 13C NMR (75 MHz, DMSO-d6) delta 111.1 112.5, 124.7, 125.5, 129.8, 133.2, 151.5, 167.0; EI-MS: calculated m/z [M]+ 177.0533, observed m/z 177.0536.General procedure: O. 5-Bromo-2-aminobenzimidazole (11) 5-Bromo-2-aminobenzimidazole (11) was synthesized according to a modified version of a reported procedure. [31] In brief, 4-bromo-1, 2-diaminobenzene (1.0 g, 5.35 mmol, 1.0 eq.) was dissolved in a 1:1 mixture of MeOH (40 mL) and water (40 mL) in a 250 mL round bottom flask. The reaction mixture was treated with CNBr (1.7 g, 16.04 mmol, 3.0 eq.) and heated at 50 C. for 1 h. After cooling to room temperature, the MeOH was removed in vacuo, and the remaining mixture was basified with 1.0 M aq. NaOH (to pH=8.0) and extracted with EtOAc (3*30 mL).

Molecular Weight:191.19
XLogP3:1.1
Hydrogen Bond Donor Count:2
Hydrogen Bond Acceptor Count:4
Rotatable Bond Count:2
Exact Mass:191.069476538
Monoisotopic Mass:191.069476538
Topological Polar Surface Area:81
Heavy Atom Count:14
Complexity:234
Covalently-Bonded Unit Count:1
Compound Is Canonicalized:Yes