[C:1]([O:5][C:6]([NH:8][CH2:9][C:10]1[N:15]=[C:14]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[CH:13]=[CH:12][CH:11]=1)=[O:7])([CH3:4])([CH3:3])[CH3:2]>CC(O)=O>[C:1]([O:5][C:6]([NH:8][CH2:9][CH:10]1[NH:15][CH:14]([C:16]([O:18][CH2:19][CH3:20])=[O:17])[CH2:13][CH2:12][CH2:11]1)=[O:7])([CH3:4])([CH3:3])[CH3:2]Ethyl 6-((tert-butoxycarbonylamino)methyl)picolinate (8.74 g, 31.2 mmol) was dissolved in AcOH and degassed with argon in a reactor (Roth), then catalytical amount PtO2 was added and degassed with argon again. The reaction was stirred at room temperature under H2 (40 bar) for 3 days. 8a was not fully converted. The reaction mixture was filtered through celite, concentrated in vacuo and purified with flash chromatography in EE. The retrieval of 8a was repeated until 100% converted with the same procedure.
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