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

摘要

P,N-sp3-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)(eta(3)-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 C-2-symmetric bisphosphine, P,N-sp2-bidentate, and P,N-sp3-bidentate ligands in tested allylic substitutions.