Ruthenium(ii)-catalyzed [5 + 1] annulation reaction: a facile and efficient approach to construct 6-ethenyl phenanthridines utilizing a primary amine as a directing group†
Abstract
A ruthenium(II)-catalyzed [5 + 1] annulation reaction between 2-arylanilines and cyclopropenones employing a free amine as a directing group has been developed. This protocol provides a facile and practical method for the preparation of a variety of biologically valuable 6-ethenyl phenanthridine scaffolds, and features the use of the cost-effective ruthenium catalyst, good functional group tolerance and no requirement of an external oxidant.