Solid-Supported Hypervalent Iodine Reagents

The practicability of catalyst 2 has been demonstrated in the synthesis of peptide aldehydes libraries targeting caspases 1 and 3 [12], The peptide aldehydes were prepared using a succession of solid phase, and polymer-assisted solution phase synthesis, and were obtained in excellent purity. 

Since this first breakthrough, other solid-supported IBX reagents have been prepared with the same strategy of attachment [13], most notably a high loading polymer prepared by the Lei group, showing improved oxidative activity when used with a small amount of triethylamine [14]. 

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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. 

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