Nickel-or Cobalt-catalyzed Asymmetric Hydrogenation

In past decades,transiton metal asymmetric hydrogenation has emerged as one of the most powerful strategies for the construction of chiral molecules,and considerable progress have been made both in academia and in industy.However,the traditional asymmetric hydrogenation are heavily dependent on ruthenium,rhodium,iridium or palladium,which suffer from the inherent drawbacks of precious matal catalyst,such as expensive,toxic and so.In contrast,the catalysts based on the cheap,earth-abundant first transition matal have the advantages in cost and sustainability.Thus,it is highly desirable for the development of cheap matal catalyzed asymmetric hydrogenation.In this paper,we devoted to the development of Ni-catalyzed asymmetric hydrogenation reactions and the design of new chiral ligands for the first row transition matal catalyzed asymmetric hydrogenation.The main contents as follows:1)In order to address the problematic issue that the control of the chemo-and enantioselectivity in asymmetric hydrogenation of?,?-unsaturated imines,Ni(OAc)₂/(S,S)-Ph-BPE/TFE,a catalytic systerm,was developed.By employing this catalytic systerm,the cheap metal catalyzed asymmetric hydrogenation of?,?-unsaturated imines have been achieved,affording a series of chiral allylic amines in high yields and excellent enantioselectivities.This protocol featured with mild conditions,wide substrate scope which provide an efficient synthetic route to chiral allylic chiral amines.Moreover,the gram scale reaction worked smoothly without loss any yied and enatioselectivity,demonstrating the protential utility of the current methodology.2)A new type of PNN ligand containing a chiral oxazoline motif have been prepared form2,6-dibromo-pyridine,and it complex with Co Cl₂ have also been synthesized.After that,the catalytic performance of the complex in asymmetric hydrogenation of ketones and alkenes have been investigated.Unfortunately,no positive results were obtained.Even so,it provided same useful information for the design of ligands and was benefit for our further investigations.