Heteroatom Chemistry Volume 19, Number 4, 2008 Silica-Supported ICl as a Novel Heterogeneous System for the Rapid Oxidation of Urazoles to Triazolinediones Bahador Karami, 1 Shadpour Mallakpour, 2 and Mahnaz Farahi 1 1 Department of Chemistry, Yasouj University, P.O. Box 353, Yasouj 75918-74831, Iran 2 Organic Polymer Chemistry Research Laboratory, Department of Chemistry, Isfahan University of Technology, Isfahan 84156-83111, Iran Received 13 November 2007; revised 14 January 2008 ABSTRACT: ICl–SiO 2 as a new reactive system was prepared by the treatment of iodine monochlo- ride with an activated silica gel in chloroform. ICl– SiO 2 in a heterogeneous system efficiently oxidized urazoles to the corresponding triazolinediones un- der mild conditions in high yields at room temper- ature. C  2008 Wiley Periodicals, Inc. Heteroatom Chem 19:389–393, 2008; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/hc.20444 INTRODUCTION In recent years, iodine monochloride (1) has been widely used for various organic transformations, such as iodination of activated aromatic substrates [1], synthesis of 6-iodo quinazoline-4(3 H)-one derivatives [2], iodination of nucleic acids in organic solvents [3], generation of electrophilic iodine from the reaction of ICl (1) with CF 3 COOAg, CH 3 COONa, or (CH 3 COO) 2 Pb [4], stereoselective iododeborona- tions and chlorodeboronations of hindered alkenyl boronate esters using either ICl–NaOMe or ICl- pyridine [5], addition to branched E-alkenes [6], syn- thesis of α-iodo β-ketosulfones from corresponding β-ketosulfones [7], and application of it as a volumet- Correspondence to: Bahador Karami; e-mail; karami@mail. yu.ac.ir. c  2008 Wiley Periodicals, Inc. ric reagent [8]. Furthermore, ICl (1), in the absence of a catalyst, has also been used as an iodinating agent. Iodine monochloride (1) has two crystalline forms α and β, and in both structures there are non- planar chains of ICl (1) molecules in a zig-zag forma- tion [9]. This compound (1) has high vapor pressure, and similarly to I 2 evaporates easily. Although it has been used frequently, it is sometimes hazardous in the use of pure iodine monochloride (1). Recently, silica-supported reagents have re- ceived considerable attention because of higher ac- tivity due to the larger surface area, high mechanical and thermal stabilities, easy handling, low toxicity, noncorrosiveity, easy separation, and work-up [10]. On the other hand, heterogeneous processes have been well studied recently for its prospective appli- cations in organic synthesis. The high efficiency of these processes is traditionally thought to be due to the above-mentioned advantages. In continuation of our studies on heterogeneous systems and solid acids [11], we report here a novel heterogeneous reagent (2) using iodine monochloride (1) supported on silica gel, as an efficient and mild reagent for io- dination and oxidation of urazoles (3) and bisura- zoles (4) to the corresponding triazolinediones (5 and 6). We decided to use ICl (1) supported on the surface of activated silica gel to obviate practical dif- ficulties and to have better handling of the reactions (Scheme 1). 4-Substituted-1,2,4-triazoline-3,5-diones have been used in a variety of reactions such as ene 389