Michael addition reactions inside a self-assembled resorcin[4]arene hexameric capsule

In the last few years there has been a significant growth of interest in performing different types of reactions in confined nanometer-scale spaces taking inspiration from the biological reactions catalysed by natural enzyme in their hydrophobic pocket.[1] In fact, the confinement of the substrates within a molecular container can lead to new reactivities and selectivities different from those normally observed in the bulk medium. Resorcin[4]arene hexameric capsules [2],[3] have been already exploited as nanoreactors thanks to their ease of preparation, their large cavity, and their ability to encapsulate different substrates and stabilize cationic intermediate.[4] Our group recently highlighted that the hydrogen-bond-donor capabilities of the bridging water molecules of the capsule are able to promote the Friedel-Crafts benzylation reaction with high efficiency and regioselectivity.[5] On this basis, we envisioned that this capability of the hexameric resorcinarene capsule could play a role in the catalysis of Michael addition of pyrrole to electron-deficient nitroolefins through the hydrogen-bonding activation of the nitroolefin and we herein report our recent results.