反应详情

Potassium tert-butoxide (1.81 g) was added to a solution of methyl 2-tert-butylcarbonylamino-6-hydroxybenzoate (Intermediate 79, 4.06 g) in THF (30 mL) and the mixture was heated at 60° C. β-propiolactone (1.16 g) was added dropwise and the resultant mixture was heated at 60° C. for 25 minutes, then left to stand at room temperature overnight. Ethyl acetate and water were added and the layers were separated. The aqueous phase was extracted with more ethyl acetate and acidified to pH 2 using 1M hydrochloric acid. This was extracted with ethyl acetate, dried (Na2SO4) and filtered. The filtrate was concentrated in vacuo and the residue was purified by chromatography on silica, eluting with a mixture of ethyl acetate and cyclohexane, with a gradient of 50-100% to give methyl 2-tert-butylcarbonylamino-6-(2-carboxyethoxy)-benzoate (3.5 g) as a white solid.

1. additionwas added dropwise
2. waitleft
3. customthe layers were separated
4. extractionThe aqueous phase was extracted with more ethyl acetate
5. extractionThis was extracted with ethyl acetate
6. dry with materialdried (Na2SO4)
7. filtrationfiltered
8. concentrationThe filtrate was concentrated in vacuo
9. customthe residue was purified by chromatography on silica
10. washeluting with a mixture of ethyl acetate and cyclohexane, with a gradient of 50-100%