[CH3:1][P:2](=[O:7])([O:5][CH3:6])[O:3][CH3:4].P(=O)([O-])[O-].C([Li])CCC.[O:17]1[CH:21]=[CH:20][CH:19]=[C:18]1[CH2:22][CH2:23][C:24](OC)=[O:25]>CCCCCC.C(O)(=O)C.O1CCCC1>[O:25]=[C:24]([CH2:23][CH2:22][C:18]1[O:17][CH:21]=[CH:20][CH:19]=1)[CH2:1][P:2](=[O:7])([O:5][CH3:6])[O:3][CH3:4]
A solution of 25 g (0.21 mole) dimethyl methylphosphonate (Aldrich) in 300 ml. dry tetrahydrofuran was cooled to -78° in a dry nitrogen atmosphere. To the stirred phosphonate solution was added 80 ml. of 2.67 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°, 16.0 g (0.104 mole) methyl 3-(2-furyl)propionate 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 6 ml acetic acid and rotary evaporated to a white gel. The gelatinous material was taken up in 75 ml. water, the aqueous phase extracted with 100 ml. portions of chloroform (3x), the combined organic extracts were backwashed (50 cc H2O), dried (MgSO4), and concentrated (water aspirator to a crude residue and distilled, b.p. 148°-50° (0.5 mm) to give 8.4 g dimethyl 2-oxo-4-(2-furyl)butylphosphonate (2C).
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