Philippe Dellis

SYNPHOS®, a new chiral diphosphine ligand: synthesis, molecular modeling and application in asymmetric hydrogenation

Abstract A new optically active diphosphine ligand, [(5,6),(5′,6′)-bis(ethylenedioxy)biphenyl-2,2′-diyl]bis(diphenylphosphine) (SYNPHOS®) has been synthesized and used in ruthenium-catalyzed asymmetric hydrogenation. This new ligand has been compared to other diphosphines (BINAP and MeO-BIPHEP), regarding their dihedral angles and the enantioselectivity in the ruthenium mediated hydrogenation reaction.

New efficient electrochemical synthesis of 1,5-dithioxylopyranosides in the presence of a sacrificial anode.

Electroreduction of the disulfide derivative RSSR (5, R= [bond]C(6)H(4)[bond]CO[bond]C(6)H(4)[bond]CN) on a mercury pool or a carbon gauze electrode in the presence of 2,3,4-tri-O-acetyl-5-thio-D-xylopyranosyl bromide (1), using a sacrificial zinc anode gave an alpha,beta anomeric mixture of [4-(4-cyanobenzoylphenyl)] 2,3,4-tri-O-acetyl-1,5-dithio-D-xylopyranoside (6) in 40-70% yield, according to the experimental conditions used (nature of solvent, electrolyte salt, and temperature). High selectivity favouring the alpha anomer of 6 is observed starting from the alpha anomer of 1. Mechanistic aspects are discussed.

Multigram-Scale Asymmetric Hydrogenation Reactions Using Ru-SYNPHOS® and Ru-DIFLUORPHOS® Catalysts

The detailed procedure for the synthesis of Ru-SYNPHOS® and Ru-DIFLUORPHOS® catalysts are described. These catalysts displayed high rates and are quite effective for the large-scale hydrogenation reactions of unsaturated compounds.