[C:1]([C:4]1[N:9]=[C:8]([C:10]([O:12][CH3:13])=[O:11])[C:7]([O:14][CH3:15])=[C:6]([NH2:16])[CH:5]=1)(=[O:3])[CH3:2].[BH4-].[Na+].C([O-])(O)=O.[Na+]>CO>[NH2:16][C:6]1[CH:5]=[C:4]([CH:1]([OH:3])[CH3:2])[N:9]=[C:8]([C:10]([O:12][CH3:13])=[O:11])[C:7]=1[O:14][CH3:15]To a 0° C. solution of methyl 6-acetyl-4-amino-3-methoxypicolinate (0.75 g, 3.35 mmol) in MeOH (11.15 ml) was added sodium borohydride (0.127 g, 3.35 mmol) by portion. The reaction mixture was stirred at room temperature (TLC monitoring). After 2 h, the reaction mixture was poured into saturated NaHCO3 and extracted with EtOAc (2×) and CH2Cl2 (1×). The combined organic layers were dried over MgSO4, filtered, concentrated and dried in vacuo to afford methyl 4-amino-6-(1-hydroxyethyl)-3-methoxypicolinate (0.548 g, 2.422 mmol, 72.4% yield) as a brown oil, which was used without further purification in the next step. 1H NMR (400 MHz, CDCl3) δ 6.72 (s, 1H), 4.76 (q, J=6.4 Hz, 1H), 4.52 (s, 2H), 3.96 (s, 3H), 3.94 (s, 1H), 3.86 (s, 3H), 1.45 (d, J=6.5 Hz, 3H).
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