Synthesis of the Dibenzofuran-Based Diphosphine Ligand BIFAP and Its Water-Soluble Derivative BIFAPS and Their Use in Ruthenium-Catalyzed Asymmetric Hydrogenation.[≠]

The novel atropisomeric ligand BIFAP and the water-soluble derivative BIFAPS, based on the 1,1′-bidibenzofuranyl backbone, are presented. Advantage is taken of the very high regioselectivity in ring functionalisation of this 1,1′-bidibenzofuranyl backbone. These ligands are used in a study on ruthenium-catalyzed hydrogenations in methanol and water. A remarkable effect of the addition of a small amount of acid was observed.