F. Robin et al., BIPNOR - A NEW, EFFICIENT BISPHOSPHINE HAVING 2 CHIRAL, NONRACEMIZABLE, BRIDGEHEAD PHOSPHORUS CENTERS FOR USE IN ASYMMETRIC CATALYSIS, Chemistry, 3(8), 1997, pp. 1365-1369
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.