[CH3:1][O:2][C:3]([C:5]1[CH:10]=[N:9][C:8]([OH:11])=[CH:7][N:6]=1)=[O:4].C(=O)([O-])[O-].[K+].[K+].Cl[C:19]([F:24])([F:23])C([O-])=O.[Na+]>CN(C=O)C>[CH3:1][O:2][C:3]([C:5]1[CH:10]=[N:9][C:8]([O:11][CH:19]([F:24])[F:23])=[CH:7][N:6]=1)=[O:4]To 5-hydroxypyrazine-2-carboxylic acid methyl ester (2.0 g, β mmol) in a glass tube reaction vessel in DMF (26 mL) was added potassium carbonate (5.3 g, 39 mmol) and sodium 2-chloro-2,2-difluoroacetate (4.0 g, 26 mmol). The reaction vessel was capped and warmed to 100° C. The reaction was stirred for 30 minutes and cooled to room temperature. The reaction was filtered washing with EtOAc. The filtrate was concentrated in vacuo. The residue was taken up into EtOAc and washed with brine. The organic layer was dried (MgSO4), filtered, and concentrated in vacuo. The residue was purified by silica gel chromatography (0-40% EtOAc/hex) to give methyl-5-(difluoromethoxy)pyrazine-2-carboxylate (0.09 g, 0.46 mmol) (0.40 g, 20%).
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