Supramolecular control over Diels-Alder reactivity by encapsulation and competitive displacement

A water-soluble M4L6 coordination cage was used as a supramolecular protecting group in the Diels-Alder reaction between furan and maleimide. Encapsulation of furan in the cage prevents the Diels-Alder reaction, while subsequent addition of a competing guest will initiate the reaction.