Synthesis and Molecular Modeling Studies of SYNPHOS®, a New, Efficient Diphosphane Ligand For Ruthenium‐Catalyzed Asymmetric Hydrogenation
A new, optically active, atropisomeric diphosphane ligand, (2,3,2′,3′-tetrahydro-5,5′-bi(1,4-benzodioxin)-6,6′-diyl)bis-(diphenylphosphane) (SYNPHOS®), has been synthesized, characterized, and used in ruthenium-catalyzed asymmetric hydrogenations. This new ligand has been compared with other atropisomeric diphosphanes (BINAP and MeO-BIPHEP) with respect to their dihedral angles calculated by molecular modeling and the enantioselectivity of their ruthenium-mediated hydrogenation reactions. (© Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim, Germany, 2003)