Hydrochloric Acid → Dimethyl (3,3-dimethyl-2-oxooct-5-yn-1-yl)phosphonate

Participants

Reaction Steps

To a suspension of 7.1 g of sodium hydride (50% suspension in oil) in 220 ml of absolute tetrahydrofuran a solution of 31.5 g of 3-methyl-2-oxo-butylphosphonic acid dimethyl ester in 74 ml of absolute tetrahydrofuran is added in drops at 24° C.; the product is stirred for 1.5 hours and then, at 0° C., 111 ml of a 1.6 molar butyl lithium solution in hexane is added drop by drop and stirred for 20 minutes. A solution of 29 g of 1-bromo-2-pentine in 44 ml of absolute tetrahydrofuran is then added to the above solution drop by drop, stirred for 3 hours at 0° C., neutralized with 3N of hydrochloric acid and concentrated in a vacuum. 50 ml of brine is added; extraction is performed three times, each time with 200 ml of methylene chloride; the organic extract is shaken twice, each time with 50 ml of brine; the product is dried with magnesium sulfate and concentrated by evaporation in a vacuum. After distillation of the residue at 0.6 Torr and 125° C., 23 g of the title compound is obtained in the form of a colorless liquid.

Provenance & Evidence