反应详情

Methyl (S)-2-amino-3-(3,5-dimethyl-4-isoxazolyl)propionate (1.3 g, 6.6 mmol) was mixed with 2M LiOH (3.3 ml, 6.6 mmol) and dioxane (3.3 ml) at 0° C. and stirred overnight under N2. The next day a TLC control (CHCl3 /MeOH/NH3 aq 1/1/0.1) of the reaction mixture showed no ester present. 1M NaHCO3 (10 ml, 10 mmol) and 9-fluorenylmethyloxycarbonyl chloride (2.6 g, 10 mmol) dissolved in dioxane (10 ml) were added to the above solution and the stirring continued for a further hour. Dioxane was removed under reduced pressure and the aqueous solution acidified with a 10% KHSO4 solution to pH 2. The solution was extracted with CHCl3 (3×20 ml), dried (MgSO4) evaporated and purified by flash chromatography (Hexane/ethyl acetate/acetic acid 10/10/1).

1. additionwere added to the above solution
2. waitthe stirring continued for a further hour
3. customDioxane was removed under reduced pressure
4. extractionThe solution was extracted with CHCl3 (3×20 ml)
5. dry with materialdried (MgSO4)
6. customevaporated
7. custompurified by flash chromatography (Hexane/ethyl acetate/acetic acid 10/10/1)