[CH2:1]([C:3]1[C:4]([O:15][CH3:16])=[N:5][C:6]2[N:7]([CH:10]=[C:11]([CH:13]=O)[N:12]=2)[C:8]=1[CH3:9])[CH3:2].[NH2:17]OS(O)(=O)=O>O>[CH2:1]([C:3]1[C:4]([O:15][CH3:16])=[N:5][C:6]2[N:7]([CH:10]=[C:11]([C:13]#[N:17])[N:12]=2)[C:8]=1[CH3:9])[CH3:2]To a rapidly stirred suspension of 19.84 g of 6-ethyl-7-methoxy-5-methylimidazo[1,2-a]pyrimidine-2-carboxaldehyde in 300 ml of water at room temperature was added all at once a solution of 13.30 g of hydroxylamine-o-sulfonic acid in 250 ml of water. After 40 minutes when the intermediate had precipitated, 8 g of solid sodium hydroxide were added and the intermediate dissolved. After 1 hour when the product had precipitated, the mixture was filtered and the solid was washed with water, dried, then crystallized from ethyl acetate to obtain 16.18 g of 6-ethyl-7-methoxy-5-methylimidazo [1,2-a]pyrimidine-2-carbonitrile (83% yield) as a pale yellow solid melting at 166°-168° C.
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