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Séminaire Chimie ED459

Developing of some methodologies using ZrCl4 as a Lewis acid and synthesis of (+)-5-Epicytoxazone

Dr. Smitha Gouni (IBMM UMR5247, équipe Lipides Antipaludiques, Montpellier)

publié le , mis à jour le

Le Jeudi 02 Octobre 2008 à 13h45
Salle de cours SC-16.01 (UM2)

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 e2 m–10) 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).

Figure 1 (cliquer sur l’image pour l’agrandir)

Figure 2
Figure 2


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