Screening of a Phosphite–Phosphoramidite Ligand Library for Palladium‐Catalysed Asymmetric Allylic Substitution Reactions: The Origin of Enantioselectivity

Abstract

We have designed a new library of readily available, highly modular phosphite-phosphoramidite ligands for asymmetric allylic substitution reactions. They are easily prepared in one step from commercially available chiral 1,2-amino alcohols. The introduction of a phosphoramidite moiety into the ligand design is highly advantageous for the product outcome. This ligand library affords high reaction rates (TOFs of up to 800 mol (mol h)(-1)) and enantioselectivities (ees of up to 99%) and, at the same time, contains a broad range of disubstituted hindered and unhindered substrate types. NMR study of the Pd-pi-allyl intermediates provide a deeper understanding of the effect of the ligand parameters on the origin of enantioselectivity.