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Studies on the Synthesis of New 3‐(3,5‐Diamino‐1‐substituted‐pyrazol‐4‐yl)azo‐thieno[2,3‐ b ]pyridines and 3‐(2‐Amino‐5,7‐disubstituted‐pyrazolo[1,5‐ a ]pyrimidine‐3‐yl)azothieno[2,3‐ b ]pyridines
Author(s) -
Ho YuhWen
Publication year - 1999
Publication title -
journal of the chinese chemical society
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.329
H-Index - 45
eISSN - 2192-6549
pISSN - 0009-4536
DOI - 10.1002/jccs.199900131
Subject(s) - chemistry , malononitrile , pyridine , yield (engineering) , hydrazine (antidepressant) , medicinal chemistry , pyrimidine , salt (chemistry) , azo coupling , organic chemistry , stereochemistry , catalysis , materials science , chromatography , metallurgy
Coupling the diazonium salt of 3‐amino‐2‐cyano‐4,6‐dimethylthieno[2,3‐ b ]pyridine 1 with malononitrile 2 gave 2‐cyano‐3‐(hydrazonomalononitrile)‐4,6‐dimethylthieno[2,3‐ b ]pyridine 3 which then reacted with hydrazine compounds 4a‐4h to yield corresponding 2‐cyano‐3‐(3,5‐diamino‐1‐substituted‐pyrazol‐4‐yl)azo‐4,6‐dimethylthieno[2,3‐ b ]pyridines 5a‐5h. The 2‐cyano‐3‐(2‐amino‐5,7‐disubstituted‐pyrazolo‐[1,5‐ a ]pyrimidine‐3‐yl)azo‐4,6‐dimethylthieno[2,3‐ b ]pyridines 7a‐7f were obtained in good yield by the cyclocondensation reaction of 2‐cyano‐3‐(3,5‐diamino‐pyrazol‐4‐yl)azo‐4,6‐dimethylthieno[2,3‐ b ]pyridine 5a with the appropriate 1,3‐diketones 6a‐6f under acidic condition.