Lone-electron pair donor quality of the imino function: Increased front strain and electronic substituent effects on sterically accelerated nitrogen inversion in imino-cyclopentanes

Abstract

2,6-Dimethyl-N-(2,2,5,5-tetramethylcyclopentylidene)aniline (4h) is obtained by permethylation; it forms salts (5) by N-protonation. Its CN double bond is strongly shielded against nucleophilic attack and cannot be hydrolyzed. Nitration and bromination occur smoothly in the aromatic p-position (12, 13), showing the directing power of the lone electron pair of the imino function. This π-donor quality is assessed by probing weaker electrophiles and by qualitative competition experiments.