Study On Iridium Catalyzed Asymmetric Hydrogenation Of Heterocyclic Compounds

Chiral heterocycles are common motifs in natural products,medicinal compounds and some biologically active compounds, consequently how to efficiently and environmentally friendly construct chiral heterocyclic compounds is attracting more and more attention.Recently, synthesis of chiral heterocyclic compounds has been intensive studied, While transition-metal-catalyzed hydrogenation is one of the most powerful, efficient and well-established methods for preparing enantiomerically enriched compounds. However more asymmetric hydrogenation of cyclic imines and enamines is carried out, and asymmetric hydrogenation of olefins far from heteroatoms is less,so organic chemists have gradually begun to treat such substrates research.This study aims to research highly flexible synthesis of chiral azacycles via Iridium-Catalyzed Hydrogenation. Through the screening of ligands, solvents, and pressure conditions, it was found that comparing with plannar and central chrial ligands,the asymmetric hydrogenation gave higher enantioselectivity with axial chiral ligands. By further screening, when the ligind is In-BiphPHOX, the reaction provides efficient access to chiral heterocycles with full conversation. In order to improve the enantioselectivity we have screened the solvent,when the solvent is o-xylene,the enantioselectivity can be as high as 98%. The conditions of the reaction were further optimized. It was found that the reaction yield and the enantioselectivity did not change when the hydrogen pressure was reduced to 2.5 bar and the time was shortened to 1 h. In large scale of substrates, most of them could achieve full conversation and excellent enantioselectivity. both the aliphatic and the aromatic-substituted compounds without influence of different electronic and steric properties.Because of the mild reaction conditions,it provides the basic conditions for industrialization...