Cucurbit[7]uril as a catalytic nanoreactor for one-pot synthesis in water of isoxazolidines

The main objective of supramolecular chemistry is to mimic the macrosystems present in nature. A goal that fits perfectly with the green chemistry guidelines. The aim of our work is to mimic nature using the hydrophobic cavity of the cucurbit[7]uril (CB[7]) to perform different dehydration and cycloaddition reactions in water. The hydrophobic cavity of CB[7] made it possible to synthesize nitrones and isoxazolidines in one-pot fashion using water as a reaction solvent. Substituted isoxazolidines were obtained from the cycloaddition of nitrones with various styrenes and cinnamates, under microwave irradiation, with a catalytic quantity of CB[7], obtaining a moderate increase in the formation of the trans adduct with respect to the reaction carried out in toluene. The mechanism of the reaction and the inclusion of reagents and products in the CB[7] cavity have been studied and rationalized by NMR spectroscopy, ESI-MS experiments, and molecular modeling calculations.