N-(5-Carboxypentyl)maleamic acid → 6-Maleimidohexanoic acid
Reaction equation
[C:1]([CH2:4][CH2:5][CH2:6][CH2:7][CH2:8][NH:9][C:10]([CH:12]=[CH:13][C:14]([OH:16])=O)=[O:11])([OH:3])=[O:2].CC([O-])=O.[Na+]>O(C(C)=O)C(C)=O>[O:16]=[C:14]1[CH:13]=[CH:12][C:10](=[O:11])[N:9]1[CH2:8][CH2:7][CH2:6][CH2:5][CH2:4][C:1]([OH:3])=[O:2]Participants
4
Reactant 2
Product 1
Reagents, catalysts & solvents 1
Procedure
The acid 14 (4.5 g, 21 mmol) was refluxed in 60 mL of (Ac)2O with NaOAc (1.72 g, 21 mmol) for 3 h. After cooling, the reaction mixture was concentrated. The residue was dissolved in EtOAc, washed with brine, dried over MgSO4, filtered and evaporated to give a deep red oil that was purified by silica gel column chromatography (CHCl3:MeOH/99:1). The maleimide product 15 was isolated as a white solid (1.4 g, 32%). 1H NMR (DMSO-d6): δ 1.18-1.24 (2H, m), 1.45-1.52 (4H, m), 2.18 (2H, t, J=7.5), 3.38 (2H, t, J=7.0), 7.01 (2H, s).