反应详情

Under argon at-60° C., 474.7 ml of a 1.61-molar butyllithium solution in hexane is added dropwise to a solution of 59 g of methanephosphonic acid dimethyl ester in 400 ml of absolute tetrahydrofuran. After 15 minutes of agitation, a solution of 34.05 g of the 2,5-dimethyl-4-hexenoic acid ethyl ester described in Example 27(b) in 100 ml of absolute tetrahydrofuran is added dropwise thereto. The reaction mixture is allowed to warm up to room temperature within 4 hours and then stirred for another 3 hours. Thereafter the mixture is combined with 26.5 ml of glacial acetic acid and concentrated under vacuum. The residue is taken up in ether/water, the aqueous phase is combined with solid sodium chloride and extracted with ether. The combined organic phases are dried over magnesium sulfate and concentrated by using a forced-circulation evaporator. The evaporation residue is purified by column chromatography on silica gel with hexane/50-100% ethyl acetate as the eluent, thus obtaining 32 g of the title compound.

1. additionis added dropwise
2. concentrationconcentrated under vacuum
3. extractionextracted with ether
4. dry with materialThe combined organic phases are dried over magnesium sulfate
5. concentrationconcentrated
6. customa forced-circulation evaporator
7. customThe evaporation residue is purified by column chromatography on silica gel with hexane/50-100% ethyl acetate as the eluent