Acetic Acid → Dimethyl 2-oxo-3-phenoxypropylphosphonate

Participants

Reaction Steps

A solution of 33.2 g (268 mmoles) dimethyl methylphosphonate (Aldrich) in 360 ml dry tetrahydrofuran was cooled to -78° in a dry nitrogen atmosphere. To the stirred phosphonate solution was added 118 ml of 2.34 M n-butyllithium in hexane solution (Alfa Inorganics, Inc.) dropwise over a period of 18 minutes at such a rate that the reaction temperature never rose above -65°. After an additional 5 minutes stirring at -78°, 22.2 g (134 mmole) methyl 2-phenoxy acetate was added dropwise at a rate that kept the reaction temperature less than -70° (20 minutes). After 3.5 hours at -78° the reaction mixture was allowed to warm to ambient temperature, neutralized with 14 ml acetic acid and rotary evaporated to a white gel. The gelatinous material was taken up in 175 ml water, the aqueous phase extracted with 100 ml portions of chloroform (3×), the combined organic extracts were backwashed (50 cc H2O), dried (MgSO4), and concentrated (water aspirator) to a crude residue and distilled, b.p. 172°-175° (0.5 mm) to give 24.6 g dimethyl 2-oxo-3-phenoxypropylphosphonate.

Provenance & Evidence