反应详情

A solution of 0.53 g (2.85 mmol) of 1,1-dimethylethyl 1-piperazinecarboxylate in 5 ml of 1,2-dichloroethane is added dropwise at about 0° C. to a solution, cooled to 0° C., of 1.1 g (3 mmol) of 2-(methylamino)-2-oxoethyl 4-nitrophenyl carbonate, prepared in step 2.2. of Example 2, in 10 ml of 1,2-dichloroethane. Stirring is continued at 0° C. for 1 hour, and then at room temperature for 3 hours. The reaction mixture is concentrated under reduced pressure and the residue thus obtained is purified by chromatography on silica gel, eluting with a 20/80 mixture of ethyl acetate and cyclohexane. The gradient is gradually increased to complete the elution with ethyl acetate. An oily residue that crystallizes from diisopropyl ether is obtained. 0.61 g of product is obtained in the form of a white solid, and is used without further purification in the following step.

1. customprepared in step 2.2
2. waitat room temperature for 3 hours
3. concentrationThe reaction mixture is concentrated under reduced pressure
4. customthe residue thus obtained
5. customis purified by chromatography on silica gel
6. washeluting with a 20/80 mixture of ethyl acetate and cyclohexane
7. temperatureThe gradient is gradually increased
8. washthe elution with ethyl acetate
9. customAn oily residue that crystallizes from diisopropyl ether
10. customis obtained