The intramolecular aromatic electrophilic substitution of aminocyclopropanes prepared by the Kulinkovich-de Meijere reaction

This article describes new examples of intramolecular Kulinkovich-de Meijere reactions applied to carboxylic amides bearing an olefin moiety and an aromatic ring at a suitable position. Upon heating, the aminocyclopropanes thus obtained undergo intramolecular aromatic electrophilic substitution to afford polycyclic systems. Among the various starting materials prepared, best results are obtained from indole and phenol derivatives. In each case, a benzylic quaternary centre is introduced at the newly-formed ring junction. On one example, the efficiency of the cyclisation has been dramatically improved using a catalytic amount of para-toluenesulfonic acid.