反应详情

Triethyl phosphonoacetate (4.7 g; 20.9 mmol) was dissolved in tetrahydrofuran (36 ml). Potassium tert-butoxide (2.3 g; 20.9 mmol) was added and the reaction mixture was stirred for 40 min at room temperature. (1,1-Dimethyl-3-oxobutyl)carbamic acid tert-butyl ester (2.5 g; 11.6 mmol) was dissolved in tetrahydrofuran (15 ml) and added dropwise to the reaction mixture which was heated to reflux for 12 h. Ethyl acetate (100 ml) and hydrochloric acid (1 N; 100 ml) were added and the phases were separated. The aqueous phase was extracted with ethyl acetate (3×50 ml). The combined organic phases were washed with an aqueous solution of sodium hydrogen carbonate (saturated; 100 ml), dried (magnesium sulfate) and evaporated in vacuo. The residue was purified by flash chromatography on silica (120 g) using ethyl acetate/heptane (1:2) as eluent to afford 2.0 g of (2E)-5-tert-butoxycarbonylamino-3,5-dimethylhex-2-enoic acid ethyl ester.

1. additionadded dropwise to the reaction mixture which
2. temperaturewas heated
3. temperatureto reflux for 12 h
4. customthe phases were separated
5. extractionThe aqueous phase was extracted with ethyl acetate (3×50 ml)
6. washThe combined organic phases were washed with an aqueous solution of sodium hydrogen carbonate (saturated; 100 ml)
7. dry with materialdried (magnesium sulfate)
8. customevaporated in vacuo
9. customThe residue was purified by flash chromatography on silica (120 g)