反应详情

温度

25 °C

24.9 g (102 mmol) of t-butyl 2-(2-amino-4-thiazolyl)-2-(Z)-hydroxyimino-acetate are dissolved in 400 ml of dimethylformamide. After the addition of 54.7 g (205 mmol) of 2-(trimethylsilyl)ethyl 2-bromo-2-methylpropionate, followed by 56.6 g (410 mmol) of finely ground potassium carbonate, the mixture is stirred at 25° C. for 4 hours in a nitrogen atmosphere. After the addition of 3 l of water, the mixture is extracted with 1.5 l of ethyl acetate. The organic phase is washed twice with 1.5 l of water. The aqueous phase is extracted with 1.5 l of ethyl acetate. The combined ethyl acetate solutions are dried over sodium sulphate and evaporated to dryness. The product is purified by flash chromatography on silica gel [hexane/ethyl acetate (2:1)] and crystallized from methanol/water. There are obtained 28.6 g (65.3%) of t-butyl 2-(2-amino-4-thiazolyl)-2-[(1-(2-(trimethylsilyl)ethoxycarbonyl)-1-methylethoxy]imino]-acetate of melting point 83° C.

1. extractionthe mixture is extracted with 1.5 l of ethyl acetate
2. washThe organic phase is washed twice with 1.5 l of water
3. extractionThe aqueous phase is extracted with 1.5 l of ethyl acetate
4. dry with materialThe combined ethyl acetate solutions are dried over sodium sulphate
5. customevaporated to dryness
6. customThe product is purified by flash chromatography on silica gel [hexane/ethyl acetate (2:1)]
7. customcrystallized from methanol/water