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Séminaires & Conférences Chimie École Doctorale 459 Jeudi 02 Octobre 2008, 13h45 Salle de Cours SC-16.01 – Université Montpellier II Department of Chemistry Kakatiya University, Warangal-506 009 Development of new methodologies involving ZrCl4 as a Lewis acid catalyst and Synthesis of (+)-epi-Cytoxazone Dr. SMITHA GOUNI IBMM, UMR 5247 -CNRS, UM 1 & UM 2, Faculty of Pharmacy, Montpellier A friendly Lewis-acid catalyst must posses the following properties: easy availability, low cost, low toxicity and high stability towards water and oxygen. The ability to work in solvent and solvent-free conditions, as well as the possibility to recover and reuse the catalyst without loss of efficiency is also noteworthy features. Zirconium belongs to group IV transition metals and it is more abundant in the earth’s crust, which makes less costly and easily available. Fortunately, Zr (IV) compounds generally have low toxicity (LD50 [ZrCl4, oral rat] = 1688 mg Kg-1) and are not considered particularly poisonous. Additionally, Zr4+ with a high charge-to-size ratio (22.22 e2m10)6 enables reactions with high to excellent yields due to strong coordination of Zr4+. The ease of handling and high catalytic activity makes the Zr (IV) compounds are potential green catalysts in synthetic organic chemistry, as evidenced by their increasing commercial use for this purpose. Our experience in using ZrCl4 as a Lewis-acid catalyst in various organic transformations involves carbon-carbon bond formation, protection-deprotection chemistry etc. will be discussed (Fig 1). Apart from this total synthesis of (+)-epi-Cytoxazone, a cytokine modulator, will also be presented (Fig 2). Cl Organic Synthesis • C-C bond formations • Reductions • ProtectionProtection-deprotections O HN O Cl Zr Cl Figure 1 Cl Easily available Low toxic Mild Lewis acid Organometallics • Reagents • Complexes OH MeO (+)-epi-Cytoxazone Figure 2