Cl[C:2]1[N:3]=[CH:4][C:5]([C:8]([OH:10])=[O:9])=[N:6][CH:7]=1.[CH:11]1([CH2:14][OH:15])[CH2:13][CH2:12]1.CC(C)([O-])C.[K+]>CN(C)C=O>[CH:11]1([CH2:14][O:15][C:2]2[N:3]=[CH:4][C:5]([C:8]([OH:10])=[O:9])=[N:6][CH:7]=2)[CH2:13][CH2:12]1A solution of 5-chloropyrazine-2-carboxylic acid (1.00 g, 6.31 mmol), cyclopropyl carbinol (1.00 mL, 12.4 mmol) and potassium tert-butoxide (2.00 g, 17.8 mmol) in dimethylformamide (20.0 mL) is heated at 100° C. for 3 hours. The reaction is cooled to room temperature, quenched with 1 M hydrochloric acid. The mixture is extracted with ethyl acetate and isopropyl alcohol/chloroform (1/10), dried over magnesium sulfate, filtered, and concentrated under reduced pressure to give the title compound (1.10 g, 90%) as a grayish solid. This acid is used directly without further purification.
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