Catalysis in Confined Self-Assembled Space

In addition, these capsules are highly size-selective and different aromatic substrates with incompatible sizes gave no reaction. The main limit of this system, which is more frequently observed for encapsulation catalysts, hes in the inability of the system to display turnover. 

Fujita and coworkers reported recently on a positively charged cage (30) as an efficient catalyst for a Diels-Alder reaction in water [30]. The stracture presents an octahedral coordination cage composed of six ds-protected 

Alder reaction of 9-hydroxymethylanthracene 31 and N-phenylmaleimide 35 in an aqueous solution of 34, leading to 9,10-adduct 36. Partially reproduced with permission from Reference [30], Copyright 2006 (AAAS). 

The examples provided here certainly show how the field of self-assembled nanocapsules is becoming a promising tool for the development of efficient and highly selective catalysts, thanks to the high versatility in terms of size, shape, and interactions of the cavities. In particular, the confinement imposed by the encapsulating structure provides an attractive tool for inducing the formation of less-favored regioisomers or alteration of the bulk physicochemical properties. 

9-hydroxymethylanthrancene 31 and N-cyclohexylmaleimide 32, within cage 30 and the subsequent Diels-Alder reaction leading to the syn isomer of 1,4-adduct 33 within the cavity of 30 (b) catalytic Diels- 

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