Bulky Reagents for Direct Modifications

Capping functionalization relies on the rigidity of the cyclodextrin and the geometry of the cap, another logical mean to access multifunctional cyclodextrin is to rely on the steric hindrance of the reagent that will be able to react only a certain number of times at certain positions. 

Bulky reagents have been mainly developed for direct modification of the primary rim ofa-cyclodextrins. Being the smallest one, the effect of steric repulsion is more efficient. The reactions used are reversible, or at least the step installing the bulky group on the hydroxyl, to allow self-correction and to produce the most stable intermediate. 

It can be noted that more than four supertrityl groups could not be introduced, even when using more equivalents of reagent and in harder conditions. 

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