Cyclodextrin organometallic catalysis

Recently, a ternary complex of cytochrome c with a polyanionic /1-cyclodextrin has been reported (85). A self-assembled supra-molecular bidentate N,P ligand for aqueous organometallic catalysis was also described (86). Although related, such systems are out of the scope of this review and will not be discussed further here. 

Application of cyclodextrins and other host molecules in aqueous organometallic catalysis... 

Finally, extraction of the important reactive species can be executed in the opposite direction, from organic phase to water. This is called inverse phase-transfer catalysis. Catalysts for such processes are mostly cyclodextrins or modified derivatives thereof. Relatively few applications of this type of PTC have been published. Whereas the present section is concerned only with the organic phase as the location of the proper chemical reaction, important contributions of inverse PTC toward organometallic catalysis are detailed in Section 4.6.2. 

This short compilation of the recent literature results convincingly demonstrates the usefulness of water-soluble supramolecular complexing agents in biphasic aqueous organometallic catalysis. Due to their availability, cyclodextrins play a major role in this field. Thinking of the relatively low price of these chemicals (a few per kg in 1998 [2]) their use on a larger scale can also be envisaged in fine chemicals production. 

C. Torque, H. Bricout, F. Hapiot, E. Monflier, Substrate-selective aqueous organometallic catalysis. How size and chemical modification of cyclodextrin influence the substrate selectivity, Tetrahedron, 2004, 60, 6487-6493. 

M. Ferreira, H. Bricout, A. Sayede, A. Ponchel, S. Foumentin, S. Tilloy, E. Monflier, Diphasic aqueous organometallic catalysis promoted by cyclodextrins how to design the water-soluble phenylphosphane to avoid interaction with cyclodextrin, Adv. Synth. Catal., 2008, 350, 609-618. 

Fig- 5 Proposed role of chemieally modified cyclodextrins as carriers in aqueous-phase organometallic catalysis. Adapted from Ref. [43]. 

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