6533b873fe1ef96bd12d59d3

RESEARCH PRODUCT

Design of P-Chirogenic Aminophosphine-Phosphinite Ligands at Both Phosphorus Centers: Origin of Enantioselectivities in Pd-Catalyzed Allylic Reactions.

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International audience; We have recently patented an unprecedented stereospecific N→O phosphinyl migration process which transforms P-chirogenic aminophosphines into phosphinites. A fine design of aminophosphine phosphinite ligands (AMPP*) derived from ephedrine and bearing a P-chirogenic center either at the aminophosphine or phosphinite moiety, was performed. The synthesis of AMPP* ligands with P-chirogenic aminophosphine moiety was based on the well-established stereospecific reaction of oxazaphospholidine-borane with organolithium reagents, followed by trapping with a chlorophosphine and borane decomplexation. Concurrently, the preparation of AMPP* ligands with P-chirogenic phosphinite moiety were performed by N→O phosphinyl migration of aminophosphines borane by heating at 50 °C with DABCO, and then reaction with chlorophosphines. AMPP* ligands were studied in palladium-catalyzed asymmetric allylic alkylations, leading to enantioselectivities from 91% (R) to 95% e.e. (S). X-ray crystallographic data for relevant Pd-AMPP* complexes and computer modeling explained the origin of the enantioselectivities based on MO interactions of most stable conformers with nucleophiles.