A modular approach for ligand design for asymmetric allylic alkylations via enantioselective palladium-catalyzed ionizations

A new class of ligands for asymmetric transition metal catalysis based on 2-(diphenylphosphino)benzoic acid was used in a mechanistically-defined palladium-catalyzed reaction in which enantiodifferentiation was the result of selective ionization of substrates derived from cis-2-cycloalkene-1,4-diols. By making rational, stepwise changes in the ligand structure, the structural requirements for good asymmetric induction were probed. The absolute stereochemistry of the products was found to be related to the chirality of the ligand in a predictable fashion