反应详情

5 ml of a 0.2N solution of m-chloroperoxybenzoic acid in methylene chloride are added dropwise at -40° C. to a solution of 0.39 g (1 mmol) of 5-difluoromethoxy-2-[(3,4-dimethoxy-2-pyridyl)methylthio]-4,6-dimethyl-1H-benzimidazole in 20 ml of methylene chloride, and the mixture is stirred for 15 minutes. 0.5 ml of triethylamine are then added and the reaction mixture is poured into 20 ml of a 1:1 mixture of 5% sodium carbonate solution and 5% sodium thiosulphate solution. After phase separation, the aqueous phase is extracted twice more with 30 ml of methylene chloride each time, and the combined organic phases are washed with sodium carbonate solution, dried over magnesium sulphate, filtered and concentrated to 2 ml. After crystallisation from diisopropyl ether, the crystals are filtered off and dried to constant weight. This gives 0.3 g (74% of theory) of the title compound as a colourless solid of m.p. 163°-164° C. (decomposition).

1. customAfter phase separation
2. extractionthe aqueous phase is extracted twice more with 30 ml of methylene chloride each time
3. washthe combined organic phases are washed with sodium carbonate solution
4. dry with materialdried over magnesium sulphate
5. filtrationfiltered
6. concentrationconcentrated to 2 ml
7. customAfter crystallisation from diisopropyl ether
8. filtrationthe crystals are filtered off
9. customdried to constant weight