P(=O)([O-])[O-].C[C:6](P(OC)(O)=O)([C:8]([O-:10])=[O:9])[CH3:7].[H-].[Na+].[CH3:18][N:19]([CH3:38])[CH:20]([CH3:37])[CH2:21][C:22]([C:31]1[CH:36]=[CH:35][CH:34]=[CH:33][CH:32]=1)([C:25]1[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=1)C=O.[CH3:39]CCC>O>[CH3:38][N:19]([CH3:18])[CH:20]([CH3:37])[CH2:21][C:22]([C:25]1[CH:30]=[CH:29][CH:28]=[CH:27][CH:26]=1)([C:31]1[CH:32]=[CH:33][CH:34]=[CH:35][CH:36]=1)[CH:7]=[CH:6][C:8]([O:10][CH3:39])=[O:9]
The phosphonate anion was generated by dropwise addition of a solution of trimethylphosphonoacetate (182 mg) in 1,2-dimethylethane (DME, 1 ml) to a slurry of 80% sodium hydride (24 mg, prewashed with hexane) in DME (3 ml). After stirring at room temperature for 30 min, a solution of 4-dimethylamino-2,2-diphenylpentanal (281 mg), as prepared in Example 1, in DME (1 ml) was added slowly. The mixture was allowed to stir for 24 hours. Water was added, and the aqueous mixture was extracted with ethyl acetate (3×). The combined extracts were washed with water and brine (once each), and dried (MgSO4). Rotary evaporation of the solution gave a crude product which was flash-chromatographed over silica gel. Elution with chloroform/methanol (20:1) yielded 93 mg of methyl 6-dimethylamino-4,4-diphenyl-2-heptenoate.
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