反应详情

Sodium hydride (0.35 g, 60% suspension in mineral oil) was added in one portion to a stirred solution of 5-amino-1-(2-hydroxyethyl)-4-(4-methylphenyl)-1-H-pyrazol-3-ol(1.0 g) (Preparation 32) in anhydrous N,N-dimethylacetamide (20 ml) under a nitrogen atmosphere at room temperature. The initial effervescence observed subsided after 2-3 minutes and an orange/brown mixture resulted. After a further 7 minutes, tert-butyldimethylsilyl chloride (0.65 g) was added to the mixture in one portion and the reaction mixture was stirred at room temperature for 2 hours. Saturated aqueous ammonium chloride (50 ml) was added to the reaction mixture and the resulting aqueous medium was extracted with ethyl acetate (2×50 ml). The combined organic extracts were washed with water (40 ml), brine (40 ml) then dried over magnesium sulfate, filtered and concentrated under reduced pressure. The residue was recrystallised from dichloromethane/hexane to give the title compound as a white solid (0.66 g). m.p. 193.5-195° C.

1. customan orange/brown mixture resulted
2. waitAfter a further 7 minutes
3. extractionthe resulting aqueous medium was extracted with ethyl acetate (2×50 ml)
4. washThe combined organic extracts were washed with water (40 ml), brine (40 ml)
5. dry with materialthen dried over magnesium sulfate
6. filtrationfiltered
7. concentrationconcentrated under reduced pressure
8. customThe residue was recrystallised from dichloromethane/hexane