反应详情

A solution of 3.63 g (10 mmol) of hydrocortisone in 150 ml of dichloromethane is mixed with 2.34 g (10.8 mmol) of N-(tert -butoxycarbonyl)-valine, 500 mg (4.1 mmol) of 4-dimethylaminopyridine and 3.1 g (15 mmol) of dicyclohexylcarbodiimide. The solution is stirred for 3 hours at room temperature, the precipitate that is produced is suctioned off and washed with dichloromethane. The filtrate is concentrated by evaporation in a vacuum. The chromatography on silica gel (hexane→hexane/ethyl acetate 1:1) provides 2.87 g (51%) of (2S)-2-((1,1-dimethylethoxycarbonyl)-amino)-3-methylbutyric acid [11β,17,21-trihydroxy-3,20-dioxo-pregn-4-en-21-yl] ester. Crystallization from dichloromethane/diisopropyl ether.

1. customthe precipitate that is produced
2. washwashed with dichloromethane
3. concentrationThe filtrate is concentrated by evaporation in a vacuum