反应详情

To a mixture of 3.2 g of 6-nitro-3,4-dihydro-2,2-dimethyl-2H-1-benzopyran-3-one, 1.2 g of methyl isothiocyanate, and 40 ml of dried N,N-dimethylformamide was added 1.9 g of potassium t-butoxide while stirring under cooling with ice. The mixture was stirred for 3 hours under ice-cooling and then allowed to stand for 12 hours. Ice-water was added thereto, and the mixture was made acidic with hydrochloric acid and then extracted with methylene chloride. The organic layer was re-extracted with 2N NaOH. The aqueous layer was made acidic with hydrochloric acid and re-extracted with methylene chloride. The organic layer was dried over magnesium sulfate and concentrated under reduced pressure. The residue was subjected to silica gel column chromatography (developing solution: n-hexane:ethyl acetate =10:1) and recrystallized from a mixed solvent of methylene chloride and n-hexane to obtain 2.33 g of N-methyl-6-nitro-3-hydroxy-2,2-dimethyl-2H-1-benzopyran-4-carbothioamide.

1. temperatureunder cooling with ice
2. stirringThe mixture was stirred for 3 hours under ice-
3. temperaturecooling
4. extractionextracted with methylene chloride
5. extractionThe organic layer was re-extracted with 2N NaOH
6. extractionre-extracted with methylene chloride
7. dry with materialThe organic layer was dried over magnesium sulfate
8. concentrationconcentrated under reduced pressure
9. customrecrystallized from a mixed solvent of methylene chloride and n-hexane