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

ABSTRACT: Stability constants for the inclusion complexes of cyclohexylphthalimide 2 and adamantylphthalimide 3 with ?-cyclodextrin (?-CD) were determined by ¹H NMR titration, K = 190 ± 50 M^-1, and K = 2600 ± 600 M^-1, respectively. Photochemical reactivity of the inclusion complexes 2@?-CD and 3@?-CD was investigated, and we found out that ?-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 ?-CD. The formation of ternary complexes with acrylonitrile (AN) and 2@?-CD or 3@?-CD was also essayed by ¹H NMR. Although the formation of such complexes was suggested, stability constants could not be determined. Irradiation of 2@?-CD in the presence of AN in aqueous solution where cycloadduct 7 was formed highly suggests that decarboxylation and [3 + 2] cycloaddition take place in the ternary complex, whereas such a reactivity from bulky adamantane 3 is less likely. This proof of principle that decarboxylation and cycloaddition can be performed in the ?-CD cavity has a significant importance for the design of new supramolecular systems for the control of photoreactivity.

SUBMITTER: Sohora M 

PROVIDER: S-EPMC7296198 | biostudies-literature | 2020

REPOSITORIES: biostudies-literature