[C:1]([O:5][C:6]([NH:8][C:9]1[CH:14]=[C:13]([CH3:15])[CH:12]=[CH:11][N:10]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2].[CH2:16]([Li])[CH2:17][CH2:18][CH3:19].[CH3:21][CH2:22][CH2:23]CCC.[OH2:27].C([O:31][CH:32](C)C)(C)C>O1CCCC1>[C:1]([O:5][C:6]([NH:8][C:9]1[CH:14]=[C:13]([CH2:15][C:16]([C:17]2[CH:21]=[CH:22][C:23]([O:31][CH3:32])=[CH:19][CH:18]=2)=[O:27])[CH:12]=[CH:11][N:10]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2]A solution of 2-tert-butoxycarbonylamino-4-methylpyridine (20 g, 97 mmol) in anhydrous tetrahydrofuran (300 mL) was cooled to −78° C. and 1.6 M n-butyllithium/hexane solution (140 mL, 0.23 mol) was added dropwise with stirring. After completion of the dropwise addition, the mixture was stirred at room temperature for 30 min and cooled to −78° C. A solution of N-(4-methoxybenzoyl)propyleneimine (25 g, 0.13 mol) in anhydrous tetrahydrofuran (50 mL) was added dropwise. After completion of the dropwise addition, the mixture was stirred at room temperature for 2 h. To the reaction mixture were added water (100 mL) and isopropyl ether (300 mL), and the obtained crude crystals were collected by filtration. The crude crystals were recrystallized from tetrahydrofuran-hexane to give the title compound (23 g, yield 69%).
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