Synthesis 2004(11): 1744-1746  
DOI: 10.1055/s-2004-829149
SHORTPAPER
© Georg Thieme Verlag Stuttgart · New York

Silica-Supported 1,3-Dibromo-5,5-dimethylhydantoin (DBH) as a Useful Reagent for Microwave-Assisted Aromatization of 1,3,5-Trisubstituted Pyrazolines under Solvent-Free Conditions

Davood Azarifar*, Mohammad Ali Zolfigol, Behrooz Maleki
Chemistry Department, School of Science, Bu-Ali Sina University, Postal code 65174, Hamadan, Iran
e-Mail: azarifar27@yahoo.com;
Further Information

Publication History

Received 16 March 2004
Publication Date:
13 July 2004 (online)

Abstract

1,3,5-Trisubstituted pyrazolines are rapidly and conveniently oxidized to their corresponding pyrazoles by 1,3-dibromo-5,5-dimethylhydantoin (DBH) under microwave irradiation and solvent-free conditions. The presence of silica gel as a supporting agent is shown to be effective in reducing the reaction times and increasing the yields.