CC(C)([O-])C.[K+].[C:7]([CH2:9]P(=O)(OCC)OCC)#[N:8].O=[CH:19][CH2:20][N:21]1[CH2:26][CH2:25][N:24]([C:27]([O:29][C:30]([CH3:33])([CH3:32])[CH3:31])=[O:28])[CH2:23][CH2:22]1>C1COCC1>[C:7](/[CH:9]=[CH:19]/[CH2:20][N:21]1[CH2:26][CH2:25][N:24]([C:27]([O:29][C:30]([CH3:33])([CH3:32])[CH3:31])=[O:28])[CH2:23][CH2:22]1)#[N:8]To a solution of 1 M of potassium tert-butoxide in THF (45.5 mL, 0.0455 mol) at 0° C. was added drop wise a solution of diethyl cyanomethylphosphonate (7.72 mL, 0.0477 mol) in THF (70 mL). The reaction mixture was warmed up to at RT, cooled to 0° C. again, and a solution of tert-butyl 4-(2-oxoethyl)piperazine-1-carboxylate (9.90 g, 0.0434 mol) in THF (10 mL) was added. The reaction mixture was allowed to warm up to RT and stirred for 2 more hours. After being quenched with water, the mixture was extracted with EtOAc. The organic layers were dried and concentrated. The residue was purified by silica gel column eluting with DCM to give the desired product (7.5 g, 69%).
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