Synthesis of new chiral diphosphine-borane complex and its application to the catalytic asymmetric hydrogenation

The high enantiomeric pure phenylglycol was synthesized from styrene by Sha rpless asymmetric dihydroxylation. The diol was converted to chiral diphosp hine-borane complex by esterification and nucleophilic substitution respect ively. The complex was superior to free phosphine ligands which are sensiti ve to atmosphere. It' s easy to prepare, purify and reserve. The complex wa s decomplexated in the presence of HBF4 . OMe2 to yield quantitatively the free diphosphine which reacted directly with [Rh(COD)Cl](2) forming in situ catalyst. The asymmetric hydrogenation of methyl z-alpha -acetamidocinnama te has been accomplished in the presence of catalyst in 100% chemical conve rsion and 88% e. e..