[CH3:1][O:2][C:3]([C:5]1[C:13]2[O:12][C:11](Cl)=[N:10][C:9]=2[CH:8]=[CH:7][CH:6]=1)=[O:4].[C:15]([O:19][C:20]([N:22]1[CH2:27][CH2:26][CH:25]([NH2:28])[CH2:24][CH2:23]1)=[O:21])([CH3:18])([CH3:17])[CH3:16].C(N(CC)CC)C>C(#N)C>[CH3:1][O:2][C:3]([C:5]1[C:13]2[O:12][C:11]([NH:28][CH:25]3[CH2:24][CH2:23][N:22]([C:20]([O:19][C:15]([CH3:18])([CH3:17])[CH3:16])=[O:21])[CH2:27][CH2:26]3)=[N:10][C:9]=2[CH:8]=[CH:7][CH:6]=1)=[O:4]To a solution of 2-chloro-benzooxazole-7-carboxylic acid methyl ester (1.50 g, 7.08 mmol, 1.0 equiv; example 252/step 3) in acetonitrile (23 mL) was added 4-amino-piperidine-1-carboxylic acid tert-butyl ester (1.42 g, 7.08 mmol, 1.0 equiv) and triethylamine (0.79 g, 7.79 mmol, 1.1 equiv). After stirring for 48 h at rt, the reaction mixture was poured on ice, the solution extracted with ethyl acetate (2×100 mL) and the combined organic phases washed with water (2×100 mL) and a conc. solution of sodium chloride (100 mL). The organic phase was dried over MgSO4, concentrated by evaporation under reduced pressure and the crude reaction product purified with column chromatography on silica eluting with hexane/ethyl acetate (1:1) providing 2.27 g (85%) of the title compound. MS (ISP): 376.4 [M+H]+.
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