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Ring transformation of 3‐halo‐4‐methoxycoumarins into pyrazoles with hydrazines
Author(s) -
Morita Hikari,
Harada Kazuho,
Okamoto Yoshihisa,
Takagi Kaname
Publication year - 1999
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570360331
Subject(s) - chemistry , phenylhydrazine , hydrazine (antidepressant) , ring (chemistry) , halo , boiling , ethanol , medicinal chemistry , stereochemistry , organic chemistry , chromatography , physics , quantum mechanics , galaxy
3‐Chloro‐ and 3‐bromo‐4‐methoxycoumarins 1a,b were readily transformed into 4‐halo‐5‐(2‐hydroxyphenyl)‐3‐oxo‐2,3‐dihydropyrazoles 2a,b with hydrazines. In the reaction of 1a,b with excess hydrazine and phenylhydrazine in boiling ethanol, unexpected 4‐hydrazono‐3‐(2‐hydroxyphenyl)‐2‐pyrazolin‐5‐ones 3 , 5 were obtained. The structure of 3 was determined by X‐ray diffraction analysis.
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