Cyclopropanation with Ruthenium Catalysts

Abstract

In this decade, a variety of ruthenium complexes have been intensively investigated that exhibit catalytic activity for cyclopropanation of olefins and diazoester derivatives producing cyclopropanecarboxylates with high stereoselectivity (trans>cis or cis>trans) and enantioselectivity (over 90% ee). In order to attain their high performance, chiral or achiral nitrogen-based compounds have been synthesized and applied as ligands to control the activity of the metal center and to construct appropriate setereochemical environments. Some of the related carbene complexes of ruthenium, thought to be intermediates for the corresponding cyclopropanation reactions, have been isolated and characterized.