Ligand Design Rationale en Route to the Trost Ligands for Asymmetric Allylations

Keywords

Trost ligands - palladium - enantioselective - rational design

Significance

Over three decades ago, the Trost group outlined their rational ligand design in the development of what are now called the ‘Trost ligands’. These ligands have applications in enantioselective allylations using palladium as a catalyst. In this case the Trost group investigated the intramolecular cyclization of a symmetric, prochiral dicarbamate. All the reported ligands use 2-(diphenylphosphino)benzoic acid (DPPBA) as the phosphine source.

Comment

Initially, Trost used ionic salts by reacting chiral amine bases with DPPBA, resulting in minimal success. Improvements were observed when a covalent ester bond was used for monodentate ligands. They next prepared C ₂-symmetric bidentate ester ligands and observed a large increase in the ee value. Restricting rotation of the backbone also improved the ee value. Lastly, switching to C ₂-symmetric diamide ligands with large dihedral angles resulted in high enantioselectivities of the products.

Publication History

Article published online:
16 December 2025