Stabilization and detection of labile reaction intermediates in supramolecular containers

Detection and observation of reactive intermediates is an essential step in investigation of reaction pathways. However, most reactive intermediates are unstable and present at low concentrations; their short lifetimes make them difficult to detect and characterize. Supramolecular containers offer opportunities for the stabilization and characterization of those labile species, through isolation from the media and protection inside the cavity of the host. In this review, we summarize the examples of labile reaction intermediates that are stabilized and characterized with the help of supramolecular containers. The container compounds include carcerands, deep cavitands and amide naphthotubes. We focus on unstable guest species – cyclobutadiene, benzocyclopropenone, o-benzyne, 1,2,4,6-cycloheptatetraene, anti-Bredt's olefin, fluorophenoxycarbene, O-acylisoamide, and hemiaminal – that act as intermediates in certain organic reactions