C(O[C:6]([NH:8][NH:9][C:10](=[O:19])[C:11]1[CH:16]=[C:15]([CH3:17])[N:14]=[C:13]([Cl:18])[CH:12]=1)=[O:7])(C)(C)C.Cl[C:21]1C=C(C=C(C)N=1)C(O)=O.N(C(OC(C)(C)C)=O)N.CN(C(ON1N=NC2C=CC=CC1=2)=[N+](C)C)C.[B-](F)(F)(F)F.CCN(C(C)C)C(C)C>CN(C=O)C.C(OCC)(=O)C.O>[Cl:18][C:13]1[CH:12]=[C:11]([C:10]2[O:19][C:6](=[O:7])[N:8]([CH3:21])[N:9]=2)[CH:16]=[C:15]([CH3:17])[N:14]=1Step-1: t-Butyl-2-(2-chloro-6-methylisonicotinoyl)hydrazinecarboxylate: To a stirred solution of 2-chloro-6-methylisonicotinic acid (4.0 g, 23.3 mmol) in DMF (40 mL) was added successively tert-butyl hydrazine carboxylate (3.0 g, 23.3 mmol), TBTU (6.0 g, 18.6 mmol) and DIPEA (12.2 mL, 69.9 mmol). After stirring for 12 hat RT, water (20 mL) was added to the reaction followed by ethyl acetate (50 mL). The layers were separated and the aqueous layer was extracted with ethyl acetate (3×50 mL). The combined organic layers were washed with brine (50 mL), dried (Na2SO4) and filtered. The filtrate was concentrated under vacuum to afford 3.0 g (45%) of the title compound as white solid. 1HNMR (400 MHz, CDCl3) δ 8.65 (s, D2O exchangeable, 1H), 7.48 (s, 1H), 7.42 (s, 1H), 6.77 (s, D2O exchangeable, 1H), 2.59 (s, 3H), 1.53 (s, 9H); GC-MS (m/z) 185 (M)+
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