Ruthenium-Catalyzed Cyclizations: More than Just Olefin Metathesis!

Abstract

From unexpected side products to new catalytic cyclizations: Numerous ruthenium-catalyzed cyclization reactions that probably proceed via five-membered ruthenium metallacycles and do not involve olefin metathesis have been described recently. The border between metathesis and nonmetathesis cyclization pathways is not always clearly defined. This phenomenon can lead to the discovery of new ruthenium-catalyzed reactions (see scheme; X=CR 2 NR).