Host-guest interaction-induced selective oxidation of a substrate inside an aqueous PdL cage.

Chemical transformations inside artificial hosts like cages have been a booming field of research. However, the use of such artificial hosts for carrying out the selective transformation of one molecule from a mixture of different molecules has been underexplored. Herein, we report the oxidation of the benzylic C(sp)-H of alkylarenes inside an aqueous PdL cage 1 without using any traditional oxidant. 1 was an efficient host in inducing complete oxidation of alkyl arenes such as xanthene, thioxanthene, fluorene, and acridine derivatives inside its cavity, which other reported analogous Pd cages did not show under similar conditions. It was also observed that encapsulation within the cage was a necessary criterion for oxidation to occur in water. Using this criterion and the higher binding affinity of cage 1 to fluorene over other fluorene derivatives such as 2-bromofluorene and 2,7-dibromofluorene, 1 was able to selectively oxidize fluorene from a mixture of fluorene derivatives through selective encapsulation. This work provides insight into an alternative approach for the selective oxidation of active methylene-containing organic compounds using differences in host-guest affinity in an aqueous environment.