Bipnor: A new, efficient bisphosphine having two chiral, nonracemizable, bridgehead phosphorus centers for use in asymmetric catalysis

Article abstract of DOI:10.1002/chem.19970030824

Optically active phosphorus ligands are widely used in homogeneous asymmetric catalysis. However, among the numerous available structures of this type, the subclass of optically active bisphosphines with at least one chiral phosphorus atom is rather underdeveloped. A bisphosphine with two chiral, nonracemizable bridgehead phosphorus centers, (meso,d/l)-2,2',3,3'-tetraphenyl-4,4',5,5'-tetramethyl-6,6'-bis-1-phosphanorb orna-2,5-dienyl (BIPNOR), can be obtained by thermolysis of 1,1'-bisphospholyl with diphenylacetylene. Here, we report the resolution of the d/l isomer by means of a chiral palladium complex to give the two optically active forms of BIPNOR. We then investigate the catalytic properties of BIPNOR, incorporated in Rh(I) and Ru(II) catalysts for the hydrogenation of olefins and ketones and in a Pd(II) catalyst for asymmetric alkylation reactions. BIP-NOR is shown to give good results in these catalytic reactions.