[N+:1]([C:4]1[CH:18]=[CH:17][C:7]([CH2:8]P(=O)(OCC)OCC)=[CH:6][CH:5]=1)([O-:3])=[O:2].O=[C:20]1[CH2:25][CH2:24][N:23]([C:26]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])=[O:27])[CH2:22][CH2:21]1.[H-].[Na+]>O1CCCC1>[N+:1]([C:4]1[CH:5]=[CH:6][C:7]([CH:8]=[C:20]2[CH2:25][CH2:24][N:23]([C:26]([O:28][C:29]([CH3:32])([CH3:31])[CH3:30])=[O:27])[CH2:22][CH2:21]2)=[CH:17][CH:18]=1)([O-:3])=[O:2]Diethyl 4-nitrobenzylphosphonate (36 g, 132 mmol) and tert-butyl 4-oxopiperidine-1-carboxylate (26.3 g, 132 mmol) were stirred in tetrahydrofuran (230 mL) and cooled in an ice bath. Sodium hydride was added (6.85 g, 171 mmol) and the reaction was taken off the ice bath and stirred for 3 hours at room temperature. The reaction was quenched with water and extracted with dichloromethane, dried (magnesium sulphate), filtered and evaporated under reduced pressure. The crude material was purified by silica chromatography using a dichloromethane solvent system. The oil obtained was triturated with heptane and filtered to give the title compound as a yellow solid (34.24 g). 1H NMR (CDCl3, 400 MHz): δ 8.18 (d, 2H), 7.33 (d, 2H), 6.40 (s, 1H), 3.54 (t, 2H), 3.43 (t, 2H), 2.46 (t, 2H), 2.38 (t, 2H), 1.48 (s, 9H)
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