Design of P-Chirogenic Aminophosphine-Phosphinite (AMPP*) Ligands at both Phosphorus Centers: Origin of Enantioselectivities in Pd-Catalyzed Allylic Reactions

Antonin Jaillet (1) , Christophe Darcel (2) , Jérôme Bayardon (1) , Adrien Schlachter (3) , Christine Salomon (1) , Yoann Rousselin (1) , Pierre D Harvey (3) , Sylvain Jugé (1)

1 ICMUB - Institut de Chimie Moléculaire de l'Université de Bourgogne [Dijon]
2 ISCR - Institut des Sciences Chimiques de Rennes
3 UdeS - Université de Sherbrooke

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.

Domains: Chemical Sciences; Chemical Sciences; Organic chemistry

Antonin Jaillet, Christophe Darcel, Jérôme Bayardon, Adrien Schlachter, Christine Salomon, et al.. Design of P-Chirogenic Aminophosphine-Phosphinite (AMPP*) Ligands at both Phosphorus Centers: Origin of Enantioselectivities in Pd-Catalyzed Allylic Reactions. Journal of Organic Chemistry, 2020, 85 (22), pp.14391-14410. ⟨10.1021/acs.joc.0c00536⟩. ⟨hal-02635117⟩