Issue 23, 2012
From the journal:

Organic & Biomolecular Chemistry

Synthesis of diversely 1,3,5-trisubstituted pyrazolesvia 5-exo-dig cyclization†

Dmitry A. Borkin,a   Mirela Puscau,b   Alena Carlson,a   Agnes Solan,b   Kraig A. Wheeler,c   Béla Török*a  and  Roman Dembinski*b  

* Corresponding authors

a Department of Chemistry, University of Massachusetts Boston, 100 Morrissey Blvd., Boston, MA 02125, USA
E-mail: bela.torok@umb.edu

b Department of Chemistry, Oakland University, 2200 N. Squirrel Rd., Rochester, Michigan 48309-4477, USA
E-mail: dembinsk@oakland.edu

c Department of Chemistry, Eastern Illinois University, 600 Lincoln Avenue, Charleston, Illinois 61920-3099, USA

Abstract

5-Exo-dig cyclocondensation of alk-3-yn-1-ones with hydrazines, in the presence of montmorillonite K-10, provides an effective method with a high atom economy for the synthesis of diversely 1,3,5-trisubstituted pyrazoles. The microwave-accelerated reaction proceeds in the absence of solvent and leads to 5-benzyl substituted pyrazoles with good yields (72–91%). The regiochemistry of the process was confirmed by the X-ray crystallographic structure determination of 1-(2-fluorophenyl)-5-(4-methylbenzyl)-3-phenyl-1H-pyrazole.

Graphical abstract: Synthesis of diversely 1,3,5-trisubstituted pyrazoles via 5-exo-dig cyclization

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Article information

DOI
https://doi.org/10.1039/C2OB25580D
Article type
Communication
Submitted
18 Mar 2012
Accepted
01 May 2012
First published
10 May 2012

Org. Biomol. Chem., 2012,10, 4505-4508

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Synthesis of diversely 1,3,5-trisubstituted pyrazoles via 5-exo-dig cyclization

D. A. Borkin, M. Puscau, A. Carlson, A. Solan, K. A. Wheeler, B. Török and R. Dembinski, Org. Biomol. Chem., 2012, 10, 4505 DOI: 10.1039/C2OB25580D

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