[CH2:1]([O:3][C:4](=[O:15])/[C:5](/[NH:11][C:12](=[O:14])[CH3:13])=[C:6](/[N:8]([CH3:10])C)\[CH3:7])[CH3:2].[CH:16]1(N)C[CH2:17]1>C(O)(=O)C.O>[CH2:1]([O:3][C:4](=[O:15])/[C:5](/[NH:11][C:12](=[O:14])[CH3:13])=[C:6](/[NH:8][CH:10]1[CH2:17][CH2:16]1)\[CH3:7])[CH3:2](Z)-2-Acetylamino-3-dimethylamino-but-2-enoic acid ethyl ester (4.3 g, 20 mmol) and cyclopropylamine (1.14 g, 20 mmol) were stirred at room temperature in acetic acid (40 ml) for 2 hrs. The reaction mixture was diluted slowly with 30 ml of water and evaporated under vacuum at 35° C. Water (30 ml) was added to the residue and evaporated again at 35° C. The same procedure was repeated twice with toluene (30 ml each) to obtain the desired crude product as a dark brown oil [MS: m/e=227.4 (M+H+)], which could be used without any further purification for the next step.
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