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Ring transformation of 3-halo-4-methoxycoumarins into pyrazoles with hydrazines

✍ Scribed by Hikari Morita; Kazuho Harada; Yoshihisa Okamoto; Kaname Takagi

Publisher
Journal of Heterocyclic Chemistry
Year
1999
Tongue
English
Weight
255 KB
Volume
36
Category
Article
ISSN
0022-152X

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✦ Synopsis

Abstract

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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ChemInform Abstract: Ring Transformation of 3-Halo-4-methoxycoumarins into Pyrazoles with Hydrazines.
✍ Hikari Morita; Kazuho Harada; Yoshihisa Okamoto; Kaname Takagi 📂 Article 📅 2010 🏛 John Wiley and Sons ⚖ 29 KB 👁 2 views

Ring Transformation of 3-Halo-4-methoxycoumarins into Pyrazoles with Hydrazines. -Treatment of (I) with hydrazine at room temperature affords the pyrazoles (II). In the reaction of (I) with excess hydrazine and phenylhydrazine unexpected pyrazolinones (III) and (V), respectively, are obtained.

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