[C:1]([N:5]1[CH2:10][CH2:9][C:8](=O)[CH2:7][CH2:6]1)([CH3:4])([CH3:3])[CH3:2].[O-]S([O-])(=O)=O.[Mg+2].[NH:18]([C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21])[NH2:19]>C(Cl)Cl>[C:1]([N:5]1[CH2:10][CH2:9][C:8](=[N:19][NH:18][C:20]([O:22][C:23]([CH3:26])([CH3:25])[CH3:24])=[O:21])[CH2:7][CH2:6]1)([CH3:4])([CH3:3])[CH3:2]To a solution of 1-tert-butylpiperidin-4-one (1.0 g, 6.5 mmol) in DCM (20 mL) was added MgSO4 (1.5 g, 13 mmol) and tert-butyl hydrazinecarboxylate (0.7 g, 5.3 mmol). The reaction mixture was heated to reflux overnight. The solid was filtered off and the filtrate was concentrated. The residue was purified by silica gel chromatography eluting with EtOAc/petroleum ether (1:20) to give tert-butyl 2-(1-tert-butylpiperidin-4-ylidene)hydrazinecarboxylate (1.2 g, 84% yield) as a colorless oil. LCMS (ESI) m/z: 270.3 [M+H+].
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