| Chiral alcohols are very important intermediates commonly used in organic reactions.The asymmetric transfer hydrogenation of prochiral ketones is one of the most effective methods to obtain chiral alcohols.Up to now,asymmetric transfer hydrogenation is catalyzed principally by precious metal complexes.However,the high price,limited availability and toxicity have seriously confined their further application.As the third most abundant transition metal in the earth’s crust,manganese is rich in reserves,low in price,and environmentally friendly.Thus,manganese complex is often used to catalyze various types of organic reactions.Nevertheless,asymmetric transfer hydrogenation of ketones based on chiral manganese catalysts have been significantly undeveloped.Therefore,it is of great significance to develop novel and efficient chiral manganese catalysts.In this thesis,the catalytic systems generated from cheap and easily available manganese complexes and chiral aminophosphine ligands are used to catalyze the asymmetric transfer hydrogenation of ketones.We characterized the structure of novel chiral manganese catalysts and investigated their catalytic performance,providing valuable information for the development of efficient chiral manganese catalysts.This thesis mainly includes the following three parts:1.The asymmetric transfer hydrogenation of ketones catalyzed by generated in situ from different chiral aminophosphine ligands and manganese complexes.It showed that the combination of chiral macrocyclic ligand(R.R,R’,R’)-CyP2N4 with[MnBr(CO)5]exhibited high catalytic activity and enantioselectivity.40 examples of aromatic and heterocyclic ketones could be enantioselectively hydrogenated to corresponding chiral alcohol with up to 99%yield and up to 95%ee.2.Using commercial available manganese complexes[MnBr(CO)5]and chiral chain tetradentate ligands(R,R)-P2N2,(R,R)-P2(NH)2 or chiral cyclic hexadentate ligand(R,R,R,R’,R’)-CyP2N4 as starting materials,novel chiral manganese complexes were conveniently synthesized and successfully obtained single crystals.Furtherly,these crystals were characterized by X-ray single crystal diffraction and infrared spectroscopy determining the structures of these chiral manganese complexes.3.The above-mentioned novel chiral manganese complexes were applied for the asymmetric transfer hydrogenation of ketones.Among them,the chiral cyclic manganese complex(R,R,R’,R’)-CyP2N4-Mn(Ⅰ)can effectively catalyze the asymmetric transfer hydrogenation of 3 8 examples of aromatic and heterocyclic ketones under mild conditions,affording high optical purity chiral alcohol with up to 99%yield and up to 92%ee. |
