Evaluation of the transannular interaction of 5-substituted [2.2]metacyclophanes carrying a diazonio group on their outer position

Abstract

A diazonio group has been introduced into the outer (13-)position of 5-substituted [2.2]metacyclophanes (MCPs) (3). The absorption maxima of the substituted [2.2]MCP diazonium salts are bathochromically shifted from those of unsubstituted reference compounds. Stability constants (log K_s) of the complexation between the [2.2]MCP diazonium salts have been measured in order to estimate their cationic character. When log K_s for [2.2]MCP diazonium salts which carry the functional groups are plotted against Brown–Okamoto’s substituent constant (σ_p⁺) for them, a linear relationship is obtained. This result establishes that the electronic effect of the functional group is transmittable between two aromatic rings in [2.2]MCPs through a transannular interaction.