[3 + 2] Cycloaddition with photogenerated azomethine ylides in β-cyclodextrin.

Stability constants for the inclusion complexes of cyclohexylphthalimide and adamantylphthalimide with β-cyclodextrin (β-CD) were determined by H NMR titration, = 190 ± 50 M, and = 2600 ± 600 M, respectively. Photochemical reactivity of the inclusion complexes and was investigated, and we found out that β-CD does not affect the decarboxylation efficiency, while it affects the subsequent photochemical H-abstraction, resulting in different product distribution upon irradiation in the presence of β-CD. The formation of ternary complexes with acrylonitrile (AN) and or was also essayed by H NMR. Although the formation of such complexes was suggested, stability constants could not be determined. Irradiation of in the presence of AN in aqueous solution where cycloadduct was formed highly suggests that decarboxylation and [3 + 2] cycloaddition take place in the ternary complex, whereas such a reactivity from bulky adamantane is less likely. This proof of principle that decarboxylation and cycloaddition can be performed in the β-CD cavity has a significant importance for the design of new supramolecular systems for the control of photoreactivity.