Br[C:2]1[N:7]=[C:6]([NH2:8])[CH:5]=[C:4]([NH2:9])[C:3]=1[C:10]#[N:11].[H][H].C([O-])(=O)C.[K+].CO>[Pd].O1CCCC1>[NH2:8][C:6]1[CH:5]=[C:4]([NH2:9])[C:3]([C:10]#[N:11])=[CH:2][N:7]=1A suspension of 21.3 g of 6-bromo-2,4-diamino-5-cyanopyridine (JACS, 80:2838-2840 (1958)) and 1 g of 20% palladium on charcoal in 250 mL of tetrahydrofuran was shaken in a Parr apparatus under an atmosphere hydrogen. After 2 hours, the reaction was stopped and 10 g of potassium acetate and 50 mL of methanol added. The reaction was recharged with hydrogen and shaken for 18 hours. The solvents were removed under reduced pressure and the residue crystallized from isopropyl alcohol to afford the title compound 2,4-diamino-5-cyanopyridine, mp 201°-202° C.
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