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.[OH-].[K+]>CS(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-chloro-pyrazine-2-carboxylic acid (1.50 g, 9.46 mmol) in dry dimethylsulfoxide (5 ml) was treated at 25° C. with cyclopropyl-methanol (1.02 g, 14.1 mmol) and powdered potassium hydroxide (2.12 g, 37.4 mmol). The mixture was heated in a microwave oven at 80° C. for 90 minutes. For the workup, the reaction mixture was quenched with an aqueous solution of citric acid (10%), then extracted with ethyl acetate (5×30 ml), followed by the extraction with a 4:1-mixture of dichloromethane and methanol. The combined organic layers were washed with brine (200 ml), dried and evaporated at reduced pressure. After lyophilization the 5-cyclopropylmethoxy-pyrazine-2-carboxylic acid (34% yield) was obtained as a white solid. MS (ISP): m/z=195.0 [M+H]+.
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