Cl[C:2]1[CH:9]=[CH:8][C:5]([CH:6]=[O:7])=[CH:4][C:3]=1[N+:10]([O-:12])=[O:11].C(=O)([O-])[O-].[Cs+].[Cs+].[NH:19]1[CH2:24][CH2:23][CH:22]([C:25]([O:27][CH3:28])=[O:26])[CH2:21][CH2:20]1.CS(C)=O>CCOC(C)=O>[CH:6]([C:5]1[CH:8]=[CH:9][C:2]([N:19]2[CH2:24][CH2:23][CH:22]([C:25]([O:27][CH3:28])=[O:26])[CH2:21][CH2:20]2)=[C:3]([N+:10]([O-:12])=[O:11])[CH:4]=1)=[O:7]
To a mixture of 4-chloro-3-nitrobenzaldehyde 57 (5.099 g, 27 mmol), cesium carbonate (9.48 g, 29 mmol), and methyl piperidine-4-carboxylate (4 mL, 27 mmol) was added DMSO (27 mL). The reaction mixture was heated to 100° C. for 30 min and diluted with EtOAc. The organic phase was washed with water (2×), brine (1×), dried over MgSO4, filtered, and concentrated in vacuo. Purification by flash column chromatography on silica gel (eluted with 30% to 50% EtOAc in hexanes) gave methyl 1-(4-formyl-2-nitrophenyl)piperidine-4-carboxylate 58 (3.45 g, 43% yield) as a yellow oil. Mass spectrum: calculated for C14H16N2O5 292.1. found 293.1 (M++1).
Wird geladen…
