EVALUATION OF THE TRANSANNULAR INTERACTION OF 5-SUBSTITUTED [2.2]METACYCLOPHANES CARRYING A DIAZONIO GROUP ON THEIR OUTER POSITION

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 hav e been measured in order to estimate their cationic character, When lo g K-s for [2.2]MCP diazonium salts which carry the functional groups a re plotted against Brown-Okamoto's substituent constant (sigma(p)(+)) for them, a linear relationship is obtained, This result establishes t hat the electronic effect of the functional group is transmittable bet ween two aromatic rings in [2.2]MCPs through a transannular interactio n.