Preparation of New Chiral Ferrocenyl Phosphin Ligands and Their Application to Asymmetric Reacions

摘要

We previously reported the preparation of chiral 1, 2-ferrocenyl diamine 1 and asymmetric transfer hydrogenation to ketones by its ruthenium complex. Although the enantiomeric excess of products was moderate (up to 75% ee), the potential of ferrocenyl diamine ligand was demonstrated. We have prepared bisferrocenyl diamine 2-a as follows; Fe(II) catalyzed homo-coupling of the ortho lithio ferrocenyl amine 3 gave the bisferrocene 4 and the retentive substitution of dimethylamino group of 4 by azide group followed by reduction to the primary amine 2-a (Scheme 1). The ruthenium complex of 2 could undergo asymmetric transfer hydrogenation to acetophenone, however, the enantiomeric excess of the product was still unsatisfactory (55% ee).