Chlorosulfonic acid → Methyl N-[6-(chlorosulfonyl)-1H-benzimidazol-2-yl]carbamate
Reaction equation
[C:1]([NH:5][C:6]1[NH:7][C:8]2[CH:14]=[CH:13][CH:12]=[CH:11][C:9]=2[N:10]=1)([O:3][CH3:4])=[O:2].[Cl:15][S:16](O)(=[O:18])=[O:17]>>[Cl:15][S:16]([C:13]1[CH:12]=[CH:11][C:9]2[N:10]=[C:6]([NH:5][C:1]([O:3][CH3:4])=[O:2])[NH:7][C:8]=2[CH:14]=1)(=[O:18])=[O:17]Participants
3
Procedure
A solution of 2-carbomethoxyamino-benzimidazole (5.0 g, 0.026 mole) in chlorosulfonic acid (35.00 mL) was stirred at 0° C. for 30 min. and at room temperature for 3 hr. The resulting dark colored reaction mixture was carefully poured into an ice-water mixture (200 mL) and stirred at room temperature for 30 min. The resulting precipitate was filtered and washed throughly with cold water (500 ml). The solid was dried overnight under high vacuum in a desiccator over NaOH pallets to yield the desired compound (5.9 g. 78%) as a grey powder. 1H NMR (DMSO-d6) 3.89 (s, 3H), 7.55 (d, 1H, J=8.4 Hz.) 7.65 (d, 1H, J=8.4 Hz), 7.88 (s, 1H).
Workup
- filtrationThe resulting precipitate was filtered