Iodine reagents ionic-liquid-supported

Figure 5.4 shows several examples of ionic-liquid-supported (also called ion-supported) hypervalent iodlne(III) reagents [93], Ion-supported (diacetoxyiodo)arenes 98-100 are prepared by the peracetic oxidation of appropriate ion-supported aryl iodides [93-95], The ion-supported tosylates 101 and 102 are made by treatment of the appropriate acetates with toluenesulfonic acid in acetonitrile [95,96] and the ion-supported iodosylbenzenes 103 and 104 are prepared by treatment of appropriate diacetates with sodium hydroxide in water [93], Ion-supported derivatives 98-104 are thermally stable solids or viscous liquids that can be used as efficient recyclable hypervalent iodine(III) reagents. Reactions of these reagents with organic substrates produce the corresponding ion-supported aryl iodides as by-products, which can be easily recovered from the reaction mixture either by extraction into an ionic liquid phase or by simple filtration. 

Handy and Okello prepared ionic liquid-supported stable and recyclable hypervalent iodine(III) reagents 19 and 20 (Figure 6) and used in the preparation of a-fxmctionalized ketones [8]. The by-product supported monovalent iodine could be easily separated from the product and recycled without compromising the product yield. In 2006, Zhang et al. reported an environmentally benign ionic liquid-supported iodine(III) reagent 21 (Figure 6) which was foxmd to be quite effective in the selective oxidation of primary alcohols [9]. 

Ionic Liquid-Supported Hypervalent Iodine Reagent... 

C. Zhu, A. Yoshimura, Y. Wei, V.N. Nemykin, V.V. Zhdankin, Facile preparation and reactivity of bifunctional ionic liquid-supported hypervalent iodine reagent a convenient recyclable reagent for catalytic oxidation. Tetrahedron Lett. 53 (2012) 1438-1444. 

Using day supported ammonium nitrate (dayan), selective deprotection of methoxyphenyl methyl (MPM) ether has been achieved recently using microwave irradiation in solvent-free conditions (Scheme 6.15) [56]. The same reagent has been used for the cleavage of tetrahydropyranyl (THP) ethers. A similar selective preparation and deavage of THP ethers has been achieved under microwave irradiation catalyzed by iodine [57] or neat reaction in an ionic liquid [28],... 

Recently, some examples of synthetic reagents anchored onto ionic liquids have been reported. These new systems present the advantage of being readily separated from the reaction mixture by simple phase separation after the desired chemical transformation and can then be regenerated and reused. For example, IL-supported hypervalent iodine compounds have been used for the oxidation of alcohols to ketones (Scheme 4.7). 

Ionic Hquids have also been used as a soluble support for catalysts, reagents, and reactants [68]. As shown in Equation 9.20, a hypervalent iodine reagent is bound to an ionic liquid and used in the tosylation reaction shown [69], The iodobenzene salt can be recovered in 95% yield and reused. 

W. Qian, E. Jin, W. Bao, Y. Zhang, Clean and highly selective oxidation of alcohols in an ionic liquid by using an ion-supported hypervalent iodine(III) reagent, Angew. Chem. Int. Ed. 44 (2005) 952-955. 

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