反应详情

Reaction of 4-aminobenzimidazole (prepared by literature methods Rabinowitz, J. L. J. Am. Chem. Soc., 1951, 73, 3030-3037; van der Want, G. M. Rec. Trav. Chim., 1948, 67, 45-51) and 2-iodo-3-nitrobenzoic acid as above gave 2-(3H-benzimidazol-4-ylamino)-3-nitrobenzoic acid (25%, crude). Purification was by treatment with ethereal CH2N2 followed by chromatograph gave methyl 2-(3H-benzimidazol-4-ylamino)-3-nitrobenzoate (18% yield); mp (EtOAc/Et2O) 146-148° C.; 1H NMR [(CD3)2SO] δ 3.69 (s, 3 H, OCH3), 6.54 (br s, 1 H, ArH), 7.00 (t, J=7.9 Hz, 1 H, ArH), 7.11-7.19 (m, 2 H, 2xArH), 8.12-8.20 (m, 3 H, 3xArH), 10.06 (br s, diphenylamine NH), 12.51 (br s, 1 H, imidazole NH). Also isolated was methyl 2-[(3-methyl-3H-imidazol-4-yl)amino]-3-nitrobenzoate (6%); mp (EtOAc) 219-221° C.; 1H NMR [(CD3)2SO] δ 3.40 (s, 3 H, OCH3), 4.09 (s, 3 H, NCH3), 6.71 (d, J=7.6 Hz, 1 H, ArH), 6.96-7.05 (m, 2 H, 2xArH), 7.43 (d, J=8.0 Hz, 1 H, ArH), 7.99 (dd, J=7.7, 1.6 Hz, 1 H, ArH), 8.11 (dd, J=8.3, 1.5 Hz, 1 H, ArH), 8.15 (s, 1 H, ArH), 9.70 (s, 1 H, NH).