Cl[C:2]1[CH:7]=[N:6][CH:5]=[C:4]([Cl:8])[N:3]=1.[NH2:9][CH:10]1[CH2:15][CH2:14][N:13]([C:16]([O:18][C:19]([CH3:22])([CH3:21])[CH3:20])=[O:17])[CH2:12][CH2:11]1.C(=O)([O-])[O-].[Cs+].[Cs+]>CN(C=O)C>[Cl:8][C:4]1[N:3]=[C:2]([NH:9][CH:10]2[CH2:11][CH2:12][N:13]([C:16]([O:18][C:19]([CH3:22])([CH3:21])[CH3:20])=[O:17])[CH2:14][CH2:15]2)[CH:7]=[N:6][CH:5]=1To a stirred solution of 2,6-dichloropyrazine (5.0 g, 34 mmol) and 4-amino-1-boc-piperidine (6.7 g, 34 mmol) in DMF (67 mL) was added cesium carbonate (22 g, 67 mmol). The reaction mixture was stirred at 100° C. After 4 h, the reaction was quenched with saturated aqueous sodium bicarbonate (100 mL) and extracted with EtOAc (3×100 mL). The combined organic layers were dried over magnesium sulfate, filtered and concentrated. The crude residue was purified by silica gel chromatography (EtOAc/Hexanes gradient) to afford tert-butyl 4-[(6-chloropyrazin-2-yl)amino]piperidine-1-carboxylate as a yellow solid. LRMS (ESI) calculated for C14H21ClN4O2 [M+Na]+, 335.1; found 335.1.
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