Chemistry of Heterocyclic Compounds, Vol. 46, No. 4, 2010 SYNTHESIS AND CRYSTAL STRUCTURE OF SOME 3,5-PYRAZOLIDINEDIONES Saoud A. M. Metwally 1 *, Maisa I. Abdel Moneim 1 , Yasser A. Elossely 1 , Radwa I. Awad 2 , Khaled Abou-Hadeed 3 Syntheses of various derivatives of 3,5-pyrazolidenedione are reported. This includes 4-arylidene (alkylidene or aralkylidene)-3,5-pyrazolidinediones, which on epoxidation gave unreported oxiranes. The syntheses of these derivatives were based on either the Knoevenagel reaction of carbonyl derivatives with 3,4-pyrazolidinedione or cyclization of arylidene (alkylidene) malonic acid hydrazide with glacial acetic acid. 4-Arylazo-3,5-pyrazolidinedione derivatives were also prepared by coupling of aryldiazonium salts with 3,5-pyrazolidinedione or cyclization of arylazomalonic acid hydrazide. Reduction of 4-benzylidene derivatives gave the corresponding benzyl derivatives. The structure of the new products was confirmed by elemental and spectral analyses and X-ray crystallography. Keywords: 3,5-pyrazolidinediones, X-ray crystallography. Historically, dyes and pharmaceuticals derived from pyrazolinones were among the first successful commercial synthetic organic chemicals in which interest has continued actively until the present day. Research in this field has culminated in the discovery of the useful anti-inflammatory properties of 4-n-butyl- 1,2-diphenyl-3,5-pyrazolidinedione (phenylbutazone) [1]. In spite of the problems encountered in the undesirable side reactions, principally agranulocytosis produced by these drugs [2-7], interest in them has never abated and one feels confident in predicting the discovery of additional useful and improved drugs in this class of compounds [8-10]. The development of new and improved dyes based on pyrazolinone structures has likewise led to modern developments of no inconsiderable magnitude. The use of tetrazine [11-14] as an approved color for foodstuffs is of significance. The synthesis of pyrazolinedione dyes for use as magenta couplers and sensitizers in color photography has been suggested [15, 16]. Metal chelate pyrazolidinone dye structures have caused a renewed interest in the use of these dyes in analytical procedures [17-19]. Recently 3,5- pyrazolidinediones have found extensive applications in veterinary medicine [20-34]. _______ * To whom correspondence should be addressed, e-mail: Saoudmetwally@hotmail.com. 1 Chemistry Department, Assiut University, Egypt. 2 Forensic Medicine Laboratories, Assiut, Egypt. 3 Institute of Organic Chemistry, University of Zurich, Switzerland. __________________________________________________________________________________________ Translated from Khimiya Geterotsiklicheskikh Soedinenii, No. 4, pp. 538-550, April 2010. Original article received January 22, 2009. After revision rewind October 31, 2009. 426 0009-3122/10/4604-0426©2010 Springer Science+Business Media, Inc.