Acetic Acid → Dimethyl(2-oxo-3,6-dimethyl-5-heptenyl)phosphonate

Participants

Reaction Steps

Under argon at -60° C., 274.7 ml of a 1.61-molar butyllithium solution in hexane was 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 2,5-dimethyl-4-hexenoic acid ethyl ester in 100 ml of absolute tetrahydrofuran was added dropwise thereto. The reaction mixture was allowed to warm up to room temperature within 4 hours and thereafter stirred for another 3 hours. Then the mixture was combined with 26.5 ml of glacial acetic acid and concentrated under vacuum. The residue was taken up in ether/water, the aqueous phase was combined with solid sodium chloride, and shaken out with ether. The combined organic phases were dried over magnesium sulfate and concentrated on a forced circulation evaporator. The evaporation residue was purified by column chromatography on silica gel with hexane/50-100% ethyl acetate as the mobile phase, thus producing 32 g of the desired compound.

Provenance & Evidence