Chiral Ligand Design: A Bidentate Ligand Incorporating an Acyclic Phosphaalkene

摘要

Since Becker's landmark discovery of the first isolable phosphaalkene just over three decades ago, there has been a growing interest in low coordinate multiply bonded phosphorus compounds. In fact, these species, although once considered exotic, are now being utilized in catalysis and materials science. As a consequence of their excellent π-acceptor properties, there has been considerable recent interest in the development of low valent phosphorus ligands for catalysis. Of particular significance are those in which the P=C donor moiety is incorporated into a cyclic structure (i.e. phosphinines phosphaferrocenes, and phospho-lides). Ligands containing acyclic P=C bonds are less well-developed, however the diphosphinidenecyclobutenes (dpcb) have been demonstrated to be highly effective in catalytic transformations. We, and others, have also reported examples of acyclic P(sp~2),N(sp~2) phosphaalkene ligands, however their application in catalysis is still at a preliminary stage of development.