Aryl diazonium salts and benzene derivatives bearing two electron-donor substituents: chemical and mechanistic behaviours.

The reaction between benzene derivatives 1-4 and p -substituted benzenediazonium tetrafluoroborates 5a-c provided novel azo-coupling products in high yields under mild conditions. The monitoring of the reaction progress using 1 H-NMR provided mechanistic information on both the relative reactivity of the reagents and the possibility to detect novel reaction intermediates.