CID 406 → Dimethyl 2-Oxo-3-(2-norbornyl)propylphosphonate

참여 물질

반응 단계

A solution of 63.9 g (0.516 mole) dimethyl methylphosphonate (Aldrich) in 645 ml dry tetrahydrofuran was cooled to -78° in a dry nitrogen atmosphere. To the stirred phosphonate solution was added 251 ml of 2.2 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 about -65°. After an additional 5 minutes stirring at -78°, 43.5 g (0.258 mole) methyl (2-norbornyl)acetate was added dropwise at a rate that kept the reaction temperature less than -70° (20 minutes). After 1.0 hour at -78° the reaction mixture was allowed to warm to ambient temperature, neutralized with 35 ml acetic acid and rotary evaporated to a white gel. The gelatinous material was taken up in 50 ml water, the aqueous phase extracted with 100 ml portions of chloroform (4x), the combined organic extracts were backwashed (50 cc H2O), dried (MgSO4), and concentrated (water aspirator) to a crude residue and distilled, dimethyl 2-oxo-3-(2-norbornyl) propylphosphonate (b.p. 138°-141°/0.3 mm).

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