O-Phenylenediamine → 4-(1h-Benzimidazol-2-yl)benzoic acid

Participants

Reaction Conditions

Reaction Steps

Resin-bound 4-carboxybenzaldehyde (subn. 0.65 mmol/g, 400 mg, 0.26 mmol) was suspended in DMA (3 mL) and treated with 1,2-phenylenediamine (2.6 mmol) and TCNE (2.6 mmol). The suspension was sonicated for 1 h and shaken at 25° C. for an additional 22 h. The resin was filtered, washed with DMA, DCM, and dried under high vacuum. The benzimidazole was cleaved from the solid support with 20% (v/v) TFA in DCM (2×5 mL, 15 min) and the combined filtrates were evaporated to give the title compound. 1H NMR (d6-DMSO) δ 7.35-7.43 (m, 2H), 7.69-7.78 (m, 2H), 8.19 (d, 2H, J=8.3 Hz), 8.26-8.34 (m, 2H), 12.50-14.20 (br s, CO2H). MS (API-ES+) m/z 239 (M+H).

Provenance & Evidence