Journal of the Chemical Society. Perkin transactions II p. 1131 - 1136 (1980)
Update date:2022-08-17
Topics:
Morris, Jeffrey J.
Page, Michael I.
The lactonisation of N-(2-aminoethyl)-6-endo-hydroxybicyclo<2.2.1>heptane-2-endo-carboxamide shows a sigmoid pH-rate profile which is interpreted, kinetically, in terms of the hydroxide-ion-catalysed hydrolysis of the amide with the terminal amino-group unprotonated and protonated.Reaction of the latter species occurs with a rate enhancement of ca. 109 compared with an amide lacking the hydroxy- and protonated amino-groups.This is attributed to intramolecular nucleophilic and general acid-catalysis.The relative effectiveness of these two processes are compared and it is concluded that intramolecular general acid-catalysis makes a relatively minor contribution to the rate enhancement even though the breakdown of the tetrahedral intermediate is thought to be a concerted process.Some comments are made about the mechanisms proposed for the chymotrypsin-catalysed hydrolysis of amides and concerted breakdown of the tetrahedral intermediate is suggested as a possible mechanism.
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