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 at atmosphere. To the stirred phosphonate solution is added 67.3 ml. (127.8 mmoles) 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 in 10 ml. of tetrahydrofuran 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 (3x), 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