The rearrangement of 1-p-fluorophenylallyl, 1-m-tolylallyl, and optically active 1-phenylallyl chlorides in NN-dimethylformamide

Abstract

Loss of optical activity by 1-phenylallyl chloride in NN-dimethylformamide occurs faster, and is much more senstitive to the ionic strength of the medium, than isomerisation to cinnamyl chloride. 1-p-fluorophenylallylchloride and 1-m-tolylallyl chloride both rearrange more rapidly than 1-phenylallyl chloride, indicating that resonance interaction occurs between the substituent and the developing charge at the reaction centre. It is suggested that isomerisation occurs by an intramolecular mechanism, with moderate charge separation in the transition state, and that racemisation involves an ion-pair intermediate in which positive charge remains essentially localised at the 1-carbon atom.