Hydrogen/deuterium (H/D) exchange at the α-H of β-carbonyl esters has been used as a useful probe to demonstrate the kinetic aspects of cucurbituril-catalyzed processes. The rate constants for H/D exchange of ethyl acetoacetate (1), methyl acetoacetate (2) and dimethyl malonate (3) have been determined in the absence and presence of cucurbit uril by 1H NMR spectroscopy. H/D exchange at the α-H of β-carbonyl esters is inhibited by cucurbituril in D2O, where the inhibitory factor order methyl acetoacetate > ethyl acetoacetate > dimethyl malonate, is in good agreement with the order of their binding constants. In the previous research, the models are oftentimes restricted to positively charged substrate. We now extend this research to neutral substrates, hence demonstrating further the versatile applications of cucurbiturils in the field of supramolecular catalysis.
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