Cluster dextrins

Figure 6.12 Proposed cluster model of smooth pea amylopectin (a) the mode of interconnection of small structural units to build up dextrin b1. Arrows trace the sub-pieces (included in boxes) of the larger dextrins (b) the fine structure of the dextrins showing how the clusters of short chains (—) are interconnected by long B-chains.261...

Breslow and co-workers have performed some of the most outstanding work in this field and their results initiated a flurry of research. They found that the rates of reaction and selectivity in the Diels-Alder reactions are improved in an aqueous system (Figure 3.6). Additionally, the presence of salts or 3-cyclo-dextrins can enhance the hydrophobic effect, which causes organic molecules to cluster together in aqueous solution, and further accelerate the Diels-Alder reaction. It should also be noted that related photochemical [2 + 2] additions can be performed using water, and in some cases these show similar rate enhancements due to hydrophobic effects. 

As shown in [21], the cluster of glycine zwitterions, like the dextrin helix, creates conditions for the presence of I2, 1 Is in solution. It implies that the discussed previously mixture (c) can be considered as a model for the drugs [17-20]. 

---