Exploiting the gem-Disubstitution Effect in FcPHOX and HetPHOX P,N Ligands: Synthesis and Applications in Pd-Catalyzed Intermolecular Heck Reactions

The synthesis of a range of novel gem-disubstituted and electronically varied thiophene–oxazoline (HetPHOX) ligands and ferrocene–oxazoline (FcPHOX) ligands and their application in the Pd-catalyzed intermolecular asymmetric Heck reaction (IAH) is described. These investigations show that gem-disubstitution of i-Pr-PHOX-type ligands can lead to effective and cost-efficient alternatives to the corresponding t-Bu-PHOX systems. The Pd complexes of these ligands were very effective in the IAH, providing phenylated products in up to 100% conversion with up to 97% ee.