C(O[C:4]([C:6]1[N:7]=[C:8]2[CH:17]=[N:16][N:15]([CH2:18][CH3:19])[C:9]2=[N:10][C:11]=1[O:12][CH2:13][CH3:14])=[O:5])C.[CH2:20]([NH2:24])[CH2:21][CH2:22][CH3:23]>>[CH2:20]([NH:24][C:4]([C:6]1[N:7]=[C:8]2[CH:17]=[N:16][N:15]([CH2:18][CH3:19])[C:9]2=[N:10][C:11]=1[O:12][CH2:13][CH3:14])=[O:5])[CH2:21][CH2:22][CH3:23]18 g. of 6-ethoxy-1-ethyl- 1H-pyrazolo[3,4-b]pyrazine-5-carboxylic acid ethyl ester (0.068 mol.), prepared according to Example 1c, are heated with 180 ml. of butylamine in an autoclave at 70° for 5 hours. After vacuum removal of excess butylamine, the residual N-butyl- 6-ethoxy-1-ethyl-1H-pyrazolo-[3,4-b]pyrazine-5-carboxamide is recrystallized from acetonitrile, m.p. 115°-117°. The mother liquor contains N-butyl-6-butyl-amino-1-ethyl-1H-pyrazolo[3,4-b]pyrazine-5-carboxamide (m.p. 128°-129°) which is identical with the compound of Example 4.
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