|
Z. Naturforsch. 2012,
67b, 765 – 773
doi:10.5560/ZNB.2012-0177
On the Synthesis and Addition Reactions of Chiral N-Heterocyclic Diphosphines
1 Institut für Anorganische Chemie, Universität Stuttgart, Pfaffenwaldring 55, 70550 Stuttgart, Germany
2 Laboratory of Inorganic Chemistry, Department of Chemistry, University of Helsinki, P. O. Box 55 (A. I. Virtasen aukio 1), 00014 University of Helsinki, Finland
Reprint requests to Prof. Dr. Dietrich Gudat. Fax: ++49 711 685 64241. E-mail:
gudat@iac.uni-stuttgart.de
Received June 29, 2012 / published online August 20, 2012
Reaction of chiral N-heterocyclic chlorophosphines with lithium diphenylphosphide or of achiral N-heterocyclic chlorophosphines with optically active lithium menthyl phosphide produces chiral N-heterocyclic diphosphines which can be utilized in subsequent diphosphination reactions with activated alkenes or alkynes. The reaction with alkynes proceeds stereospecifically to produce Z-ethylene-1,2-bisphosphines which are readily converted to nickel(II) or palladium(II) complexes. Reactions with alkenes are synthetically less useful as the addition proceeds without any chiral induction at the newly formed stereocenters to yield inseparable mixtures of diastereomeric products. The molecular structures of chiral Z-ethylene-1,2-bisphosphine complexes and of a chiral N-heterocyclic chlorophosphine have been determined by single-crystal X-ray diffraction.
Key words: Diphosphines, Chiral Ligands, N-Heterocyclic Phosphines, Diphosphination, Phosphine Complexes