Cyclodextrins reactions mediated

NMR studies of cyclodextrin and cyclodextrin complexes 98CRV1755. Organic reactions mediated by cydodextrins 98CRV2013. 

The present review deals with a particular aspect of the chemistry of cyclodextrins the effects that they can have on organic reactions by virtue of their abilities to bind to many organic and inorganic species (Bender and Komiyama, 1978 Saenger, 1980 Szejtli, 1982). It is a considerable expansion of an earlier work (Tee, 1989) which first showed how the Kurz approach to transition state stabilization can be employed profitably in discussing reactions mediated by cyclodextrins. Most of the large amount of data that are analysed is collected in tables in the Appendix so as to avoid breaking up the discussion in the main text too frequently. 

K. Takahashi, Reactions mediated by cyclodextrins, the chapter after next in this book. 

Reactions Mediated by Cyclodextrins 99 Table 4.1 The formation constants of various guests with trans- and c s-AzCD... 

K. Takahashi, Organic reactions mediated by cyclodextrins, Chem. Rev., 1998, 98, 2013-2034. 

Takahashi, K. "Organic Reactions Mediated by Cyclodextrins." Chem. Rev., 98,2013-2033 (1998). 

Provided due attention is paid to the potential deprotonation of the substrate, and of the cyclodextrins (VanEtten et al., 1967a,b Gelb et al., 1980, 1982 Tee and Takasaki, 1985), the value of Ks should not be pH dependent. However, for many reactions, such as the widely studied ester cleavage, ku, kc, and k2 are all dependent on the pH of the medium. This makes direct comparisons between the observed constants for different CD-mediated reactions either difficult or problematical. However, in general, the ratios kc/ku and k2/ku are independent of pH and so are more useful for comparative purposes. 

Ravichandran, R. P-Cyclodextrin mediated regioselective photo-Reimer-Tiemann reaction of phenols. J. Mol. Catal. A Chemical 1998,130, L205-L207. 

Terephthalic acid. Benzene is selectively converted to tetrephthalic acid (46 mol% yield) in a Cu mediated reaction with CCI4 in the presence of NaOH and p-cyclodextrin. The C—C bond formation occurs when benzene is trapped in the cavity of P-cyclodextrin. 

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