BIPNOR - A NEW, EFFICIENT BISPHOSPHINE HAVING 2 CHIRAL, NONRACEMIZABLE, BRIDGEHEAD PHOSPHORUS CENTERS FOR USE IN ASYMMETRIC CATALYSIS

Optically active phosphorus ligands are widely used in homogeneous asy mmetric catalysis. However, among the numerous available structures of this type, the subclass of optically active bisphosphines with at lea st one chiral phosphorus atom is rather underdeveloped. A bisphosphine with two chiral, nonracemizable bridgehead phosphorus centers, -tetra methyl-6,6'-bis-1-phosphanorborna-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 palladiu m complex to give the two optically active forms of BIPNOR. We then in vestigate 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. BIPNOR is shown t o give good results in these catalytic reactions.