Preparation and structures of some new 1H-pyrazole
Received: 22 March 2012 / Accepted: 30 July 2012 / Published online: 19 August 2012
Ó Springer Science+Business Media B.V. 2012
Abstract Some new 3,5-diaryl-1H-pyrazoles were prepared from aryl methyl
ketones via Claisen condensation with aromatic esters and followed by cyclization
with hydrazine monohydrate. Their structures were conﬁrmed by IR,
spectroscopy, mass spectrometry and elemental analysis. The X-ray structure for
3(5)-(4-tert-butylphenyl)-5(3)-(4-methoxyphenyl)-1H-pyrazole (2b) was presented.
The results show that compound 2b exists as tautomers I and II, and its molecules
are connected by the N–HÁÁÁN intermolecular hydrogen bonds to form cyclic dimers
consisting of the tautomers I and II.
Keywords 1H-Pyrazole Á Preparation Á Crystal structure Á Hydrogen bonds
Pyrazoles are of great interest to the biochemical community due to their wide range
of biological activities, such as analgesic, antimicrobial, anti-inﬂammatory and
antihypertensive properties [1–3]. Recently, we have synthesized some aromatic
1,3-diketones used as ultraviolet absorbents . As 1,3-diketones are well-known
intermediates in the broadest and most efﬁcient route to 1H-pyrazoles [5–7], we
undertook studies on 1H-pyrazole derivatives as an extension of our previous work.
Currently, we have studied the structures and anti-microbial activity of some
substituted pyrazoles [8, 9]. In this paper, some new 1H-pyrazoles were prepared
and characterized by FTIR,
H NMR spectroscopy, mass spectrometry and
elemental analysis. The compound 3(5)-(4-tert-butylphenyl)-5(3)-(4-methoxy-
phenyl)-1H-pyrazole (2b) was used to carry out the X-ray structure determination.
D.-J. Wang (&) Á Y.-F. Kang Á C.-Y. Zheng Á X.-H. Wei
Hubei Key Laboratory of Pollutant and Reuse Technology, College of Chemistry
and Environmental Engineering, Hubei Normal University, Huangshi 435002, China
Res Chem Intermed (2013) 39:2311–2320