C([Li])CCC.[CH3:6][P:7](=[O:12])([O:10][CH3:11])[O:8][CH3:9].[CH2:13]([C:17](=[CH2:23])[C:18](OCC)=[O:19])[CH2:14][CH2:15][CH3:16].C(O)(=O)C>C(OCC)C.O1CCCC1>[O:19]=[C:18]([C:17](=[CH2:23])[CH2:13][CH2:14][CH2:15][CH3:16])[CH2:6][P:7](=[O:12])([O:10][CH3:11])[O:8][CH3:9]
A 2N solution (400 ml.) of n-butyllithium in diethyl ether was added dropwise to a solution of dimethyl methylphosphonate (110 g.) in pure anhydrous tetrahydrofuran (700 ml.) with stirring under nitrogen, while the reaction temperature was kept within the range of -50° to -60°C. After 10 minutes, a solution of ethyl 2-n-butylacrylate (prepared as described in (1) above; 60 g.) in tetrahydrofuran (150 ml.) was added dropwise to the reaction mixture at -65° to -70°C. and stirred for 4 hours at the same temperature. The reaction mixture was further stirred overnight at 0°C, acidified with acetic acid and concentrated under reduced pressure. Diethyl ether and water were added to the residue in order to remove the water soluble materials. The ethereal solution was dried over magnesium sulphate and concentrated. The residue was distilled under reduced pressure to give pure dimethyl 2-oxo-3-methylene-n-heptylphosphonate (67 g; 69%), having the following physical characteristics:-
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