Dimethyl Sulfate → 6-Benzoyl-1-methyl-2-(2-pyridylsulfinylmethyl)benzimidazole

Participants

Reaction Steps

A mixture of 3.61 g of 5-benzoyl-2-(2-pyridylsulfinylmethyl)benzimidazole (0.01 mole), 0.40 g of sodium hydroxide (0.01 mole) and 2 ml of dimethyl sulfate (0.02 mole) in 50 ml of ethanol and 5 ml of water is maintained under reflux for 3 hours. The ethanol is evaporated off and the residue diluted with water and extracted with chloroform. The organic phase is washed with water, dried and evaporated. The residue is chromatographed with silica gel, using chloroform/methanol (99:1) and subsequently chloroform/methanol (95:5) as eluant. On fractional crystallization of the final fraction in ethyl acetate, 0.47 g (12.5%) of 5-benzoyl-1-methyl-2-(2-pyridylsulfinylmethyl)benzimidazole, melting point 174°-177° C., and 1.5 g (40%) of 6-benzoyl-1-methyl-2-(2-pyridylsulfinylmethyl)benzimidazole, melting point 181°-183° C., are obtained.

Provenance & Evidence