Phosphorus Heterocycles: From Laboratory Curiosities to Ligands in Highly Efficient Catalysts

Phosphabenzenes and phosphaferrocenes were among the first compounds with P−C multiple bonds. For nearly 30 years the chemistry of these molecules was essentially a domain left to basic researchers. Recently, however, it was reported that transition metal complexes with phosphabenzene and phosphaferrocene ligands exhibit remarkable potential as catalysts. Catalysts based on rhodium ( I ) and various phosphabenzenes appear to be superior to classical systems in the hydroformylation of terminal and internal alkenes. In addition planar‐chiral phosphaferrocene species display an excellent performance as directing ligands in a series of enantioselective asymmetric syntheses.