Other Reactions Catalyzed by Coordinated Template Catalysts

4 Other Reactions Catalyzed by Coordinated Template Catalysts 

Intramolecular catalyses of cleavage reactions at carboxylic acid derivatives are well known, and outside the scope of this book. However, cleavage reactions can also be catalyzed by species that bind to the substrate and carry out a selective reaction that depends on the geometry of the mixed complex. Since this is in the spirit of the rest of what has been described, it will be briefly included here. Such reactions imitate enzymatic cleavage processes, so they are biomimetic in the same sense that selective functionalizations within mixed complexes are biomimetic [1]. The work using cyclodextrin binding has been extensively reviewed recently [30]. 

Esters can also be cleaved by reaction with the hydroxyl group of cyclodextrin within a complex [85-91]. Some very high rates have been observed, and calculations account for the geometric preferences in such reactions. 

6 Biomimetic Reactions Directed by Templates and Removable Tethers 

Phosphate esters can be cleaved by template catalysts, especially those with cyclodextrin binding groups and linked catalytic groups. Catalysis of the hydrolysis of a bound cyclic phosphate by ribonuclease mimics has been extensively studied [92-98], as has catalysis by enzyme mimics carrying bound metal ions [99-102]. 

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