p-Toluenesulfonic acid → Methyl 1H-benzimidazole-4-carboxylate

Participants

Reaction Conditions

Reaction Steps

Ester 2 (1.7 g, 10.2 mmol), triethyl orthoformate (2.5 mL) and p-toluenesulfonic acid (10 mg) were mixed in “Performance Fluid” (3M Co., 40 mL) and refluxed with reversed Dean-Stark trap at 90° C. for 3 h. The reaction mixture was cooled to room temperature and the solid formed was filtered, washed with hexanes and dried to give 1.65 g (92%) of pure 3: 1H NMR (DMSO-d6) δ 12.59 (br.s, 1H), 8.32 (s, 1H), 7.97 (d, 1H, J=8.0 Hz), 7.86 (d, 1H, J=6.5 Hz) 7.32 (t1, 1H, J=8.0 Hz), 3.95 (s, 3H).

Provenance & Evidence