[N:1]1[CH:6]=[CH:5][N:4]=[CH:3][C:2]=1[NH2:7].C([Mg]Cl)(C)C.[CH3:13][C@@:14]1([C:26](OC)=[O:27])[CH2:18][CH2:17][CH2:16][N:15]1C(OC(C)(C)C)=O>C1COCC1>[CH3:13][C@@:14]1([C:26]([NH:7][C:2]2[CH:3]=[N:4][CH:5]=[CH:6][N:1]=2)=[O:27])[CH2:18][CH2:17][CH2:16][NH:15]1To a stirred solution of pyrazin-2-amine (1.56 g, 16.44 mmol) in THF (30 ml) was added isopropyl magnesium chloride (7.8 ml, 15.62 mmol) (2.0 M THF solution) dropwise at 0° C. under nitrogen. The resulting suspension was stirred at RT for 30 min. A solution of (S)-1-tert-butyl 2-methyl 2-methylpyrrolidine-1,2-dicarboxylate (1.0 g, 4.11 mmol) solid was added to the reaction mixture. The reaction mixture was stirred at RT for 6 h, quenched with MeOH, and concentrated. The residue was dissolved in EtOAc (120 ml) and washed with 1N HCl to remove the excess pyrazin-2-amine, water, and brine, dried over Na2SO4. The crude product was dissolved in methanol and 4N HCl in dioxane (4 mL) was added. The reaction mixture was stirred at room temperature overnight and the crude product was used in the next step without further purification.
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