4-Chlorobenzenesulfonyl chloride → 1-(4-chlorobenzenesulfonyl)-5-difluoromethoxy-2-[(3,4-dimethoxy-2-pyridyl)methylsulfinyl]-1H-benzimidazole

Participants

Reaction Conditions

Reaction Steps

5-Difluoromethoxy-2-[(3,4-dimethoxy-2-pyridyl)methylsulfinyl]-1H-benzimidazole, sodium salt sesquihydrate (432 mg, 1 mmole) was suspended in 30 ml of dichloromethane in the presence of anhydrous sodium carbonate (100 mg). 4-Chlorobenzenesulfonyl chloride (211 mg, 1 mmole) was added to the suspension and stirred at 4° C. overnight. The organic layer was separated by filtration and concentrated under reduced pressure. The residual solid was crystallized from dichloromethane-ethyl ether-heptane. 417 mg of isomer, 1-(4-chlorobenzenesulfonyl)-5-difluoromethoxy-2-[(3,4-dimethoxy-2-pyridyl)methylsulfinyl]-1H-benzimidazole and 1-(4-chlorobenzenesulfonyl)-6-difluoromethoxy-2-[(3,4-dimethoxy-2-pyridyl)methylsulfinyl]-1H-benzimidazole (5:4 ratio by NMR), was obtained. Yield 74.5% M.P. 82-83° C.

Provenance & Evidence