CID 406 → Dimethyl (3,3-dimethyl-2-oxoheptyl)phosphonate

Participants

Reaction Steps

A solution of 18.4 g. (0.116 moles) dimethyl methylphosphonate (Aldrich) in 200 ml. dry tetrahydrofuran is cooled to -78° in a dry nitrogen atmosphere. To the stirred phosphonate solution is added 67.3 ml. of 1.90 M n-butyllithium in hexane solution (Alfa Inorganics, Inc.) dropwise over a period of 40 minutes at such a rate that the reaction temperature never rose above -65°. After an additional 5 minutes stirring at -78°, 10.2 g. (58.1 mmoles) methyl 2,2-dimethylhexanoate is added dropwise at a rate that kept the reaction temperature less than -70°(20 minutes). After 1.0 hour at -78° the reaction mixture is allowed to warm to ambient temperature, neutralized with 10 ml. acetic acid and rotary evaporated to a white gel. The gelatinous material is taken up in 75 ml. water, the aqueous phase extracted with 100 ml. portions of chloroform (3×), the combined organic extracts are backwashed (50 cc H2O), dried (MgSO4), and concentrated (water aspirator) to a crude residue and distilled (b.p. 80°-85° at 0.05 mm) to give dimethyl 2-oxo-3,3-dimethylheptylphosphonate.

Provenance & Evidence