The Phthalimidomethyl Rearrangement

Abstract

The discovery of a new acid-catalysed monodentate N → C aromatic rearrangement, namely the phthalimidomethyl rearrangement, is reported. In this rearrangement, discovered during the reaction of N-hydroxymethylphthalimide with certain alkyl N-(4-nitrophenyl)carbamates in concentrated sulfuric acid solution, the phthalimidomethyl group migrates from its initial location on the nitrogen atom of the carbamate function to a carbon atom of the nitrophenyl group. Evidence, provided by an appropriate 'crossover' experiment, indicates that the rearrangement is intermolecular. Hindered rotation about the N(carbamoyl)-aryl bond of the N-phthalimidomethyl derivatives of both ethyl and methyl N-(2,4-dinitrophenyl)carbamate is reported.