Kupfer-katalysierte oxidative Heterocyclisierung mittels Luftsauerstoff

Complexes of Schiff Bases and Intermediates in the Copper-Catalyzed Oxidative Heterocyclization by Atmospheric Oxygen§

“…Previously, an ecologically compatible synthesis of new heterobicyclic compounds was described, which can be applied as pharmaceuticals or ligands for the development of new homogeneous catalysts. 1a,b Imidazo[1,5- a ]pyridines 2 , an imidazo[1,5- a ]imidazole 3 , and an imidazo[5,1- a ]isochinoline 4 were prepared from Schiff bases 1a ,1c 1b , and 1c − d 1a with an oxidative ring closure reaction by atmospheric oxygen and catalytic amounts of copper(II) and a base (Chart ). This method easily and rapidly yields new nitrogen-fused heterocycles which cannot be prepared in the traditional synthetic way of dehydrating amides under severe conditions. − Even sensitive functional groups such as hydroxy or amine groups at aromatic positions of the Schiff bases 1a − c do not disturb the catalysis.…”