The search for efficient intramolecular proton transfer from carbon: the kinetically silent intramolecular general base‐catalysed elimination reaction of O‐phenyl 8‐dimethylamino‐1‐naphthaldoximes

Abstract

AbstractThe ready elimination of phenol/phenoxide from the O‐phenyl oxime 10E derived from 8‐dimethylamino‐1‐naphthaldehyde, necessarily involving proton transfer from carbon, is catalysed by the neighbouring NMe2 group at pH > 9. However, reaction is faster, rather than slower, at lower pH. It is shown that the step involving proton transfer is not cleanly rate determining at any pH: the preferred route involves syn/anti isomerization to form the more reactive Z‐isomer. The rate constant for the anti elimination cannot be extracted from the available data, so no reliable estimate of effective molarity (EM) is possible. Copyright © 2004 John Wiley & Sons, Ltd.