Online article for Non-subscribers

Pay per view

Heterocycles has a pay-per-view service for Non-subscribers.
You will be able to directly purchase the full text article through PayPal.
Your purchased Paper can be downloaded after the payment is completed.
An e-mail will be sent the URL to download the paper.
If you have any questions, please contact: purchase@heterocycles.com

Price: ¥ 4,400 (Yen only)
Period: This Article can be accessed for 7 days.

Review | Regular issue | Vol 63, No. 1, 2004, pp.145-173
Published online, 14th November, 2003
DOI: 10.3987/REV-03-569
Structural Revision in Pyrazole Chemistry

Devinder Kumar* and Shiv P. Singh*

*Department of Applied Chemistry, Guru Jambheshwar University, Hisar-125001, Haryana, India

Abstract

Reaction of several heteroarylhydrazines with β-diketones has been incorrectly reported to generate triazepines or diazepines. It has now been firmly established that these reactions lead to the formation of pyrazoles. Further, many workers have reported the formation of pyrazoles in the reaction of heteroarylhydrazines with trifluoromethyl 1,3-diketones, whereas the actual products were found to be 5-hydroxy-5-trifluoromethyl-4,5-dihydro-1H-pyrazoles. It was also established that with a trifluoromethyl β-diketone and hydrazines, the location of the CF3 group at position 3 or 5 of pyrazoles depends on the nature of the hydrazine. Erroneous reports concerning the structure of the products obtained by the reaction of dehydroacetic acid with hydrazines have also been revised.