Metal-mediated asymmetric alkylation using chiral N-heterocyclic carbenes derived from chiral amines

The significant advances in achiral catalysis using N-heterocyclic carbene (NHC) metal complexes have prompted intense investigation of chiral NHC derivatives for use in asymmetric catalysis in recent years. Discovery of new chiral NHC catalysts is supported by the development of synthetic routes to chiral NHC ligands and their metal complexes. Here routes to chiral NHC ligands derived principally from chiral diamines will be outlined and metal complex structures described in the context of application to asymmetric catalysis. Emphasis will be placed on palladium and copper catalysed asymmetric alkylations that serve to illustrate the potential and some limitations of NHC-based asymmetric catalysts. (c) 2006 Elsevier B.V. All rights reserved.