Asymmetric synthesis and the coordination chemistry of a P-chiral diphosphine monoxide

• Published in: Inorganica Chimica Acta Vol. 352; pp. 213 - 219
• Main Authors: Teo, Tang-Wee, Selvaratnam, S, Vittal, Jagadese J, Leung, Pak-Hing
• Format: Journal Article
• Language: English
• Published: Elsevier B.V 06.08.2003
• Subjects: Asymmetric synthesis; Diels–Alder reaction; Diphosphine monoxide; Gold complexes; Palladium complexes; Diphosphine monoxide; Asymmetric synthesis; Diels–Alder reaction; Palladium complexes; Gold complexes
• ISSN: 0020-1693; 1873-3255
• DOI: 10.1016/S0020-1693(03)00154-3

The organopalladium complex containing ortho-metalated ( R)-(1-(dimethylamino)ethyl)-naphthalene as the chiral auxiliary has been used successfully to promote the asymmetric [4+2] exo-cycloaddition reaction between 1-phenyl-3,4-dimethylphosphole and vinyldiphenylphosphine oxide. The resulting P-chiral phosphanorbornene was obtained as a P–O bidenate chelate on the palladium template. The phosphanorbornene (−)-(L) could be liberated from the palladium template as a highly air-sensitive oil by the treatment of the template complex with aqueous potassium cyanide. Upon recoordination to the Au(I) ion, the diphosphine monoxide coordinated to Au(I) as a monodentate ligand via its tertiary phosphorus donor atom to form the linear complex (+)-[(L– P)AuCl]. The chloro ligand and the pendant PO group in the gold complex showed significant hydrophilicity as they both formed hydrogen bondings to a water molecule. However, the neutral gold complex is not soluble in water. The asymmetric [4+2] exo-cycloaddition reaction between 1-phenyl-3,4-dimethylphosphole and vinyldiphenylphosphine oxide was achieved in the presence of the organopalladium complex containing ortho-metalated ( R)-(1-(dimethylamino)ethyl)-naphthalene. The resulting P-chiral (−)-phosphanorbornene was obtained as a stable P–O bidenate chelate on the palladium template and could be liberated as a highly air-sensitive oil by the treatment of aqueous potassium cyanide. The cycloadduct coordinated as a monodentate phosphine to Au(I) with the pendant PO group showing significant hydrophilicity.