Preparation and Application of Amino Phosphine Ligands Bearing Spiro[indane-1,2′-pyrrolidine] Backbone

P,Nsp3-bidentate chiral ligands bearing spiro­[indane-1,2′-pyrrolidine]
backbone were prepared in gram scale for the first time. Pd complexes
of these air-stable amino phosphine ligands could catalyze asymmetric
allylic substitutions of malonate-, alcohol-, and amine-type nucleophiles
in up to 97% ee and 99% yield. A crystal structure of [Pd­(II)­(η3-1,3-diphenylallyl)­(ligand)]­PF6 indicated possible
transition states of the catalytic reactions. These ligands are characteristic
of a very rigid backbone, which is simple but highly effective. They
rival C2-symmetric bisphosphine, P,Nsp2-bidentate, and P,Nsp3-bidentate
ligands in tested allylic substitutions.