Formic Acid → 6-(methylthio)-1H-benzimidazole

Participants

Reaction Steps

4-(Methylthio)benzene-1,2-diamine (10.7 g, 69.2 mmol) was dissolved in 230 mL of aqueous 4N HCl with stirring. Formic acid (7.85 mL, 208 mmol) was added and the reaction was refluxed for 1 h. The reaction was cooled to rt then concentrated in vacuo to a dark solid. The dark solid was dissolved In 500 mL of MeOH with stirring, NaHCO3 (51.0 g, 607 mmol) was added and the reaction was stirred for 1 h. The reaction was then filtered, and the filtrate concentrated in vacuo to a solid. The solid was stirred in 400 mL of EtOAc and heated to reflux, then filtered. The filtrate was concentrated in vacuo to a solid. The solid dissolved in 400 mL of DCM with stirring, then dried over MgSO4, and filtered. The filtrate was concentrated in vacuo to give 11.3 g (99%) of the crude 6-(methylthio)-1H-benzimidazole as a dark oil. 1H NMR (400 MHz, CD3OD) δ 8.12 (s, 1H), 7.52 (m, 2H), 7.24 (m, 1H), 2.50 (s, 3H). MS m/z 165 (M+1).

Provenance & Evidence