EN
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
cucurbit[7]uril-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[7]
uril by 1H NMR spectroscopy. H/D exchange at the α-H of β-carbonyl
esters is inhibited by cucurbit[7]uril 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.