The Research Of New Double Axially Chiral Bronsted Acid Catalyzed Asymmetric Hydrogenation Of3-H-indoles

In recent years, Hantzsch esters and related organic reducing agents have beenwidely used in asymmetric transfer hydrogenation (ATH). Most of these reactionsusing chiral secondary amines, chiral thiocarbamides and chiral phosphoric acids, theuse of these catalytic systems can beasymmetric reduction a variety of unsaturatedbonds.The reaction conditions are relatively mild, The yields and chirality controlability of this reaction is very good.This paper through the synthesis of spiro doubleaxially chiral phosphorus imide and using double axially chiral phosphorus imidecatalyst asymmetric hydrogenation of3-H indoles, and obtained the better catalyticresults.First of all, this article introduces the development and significance ofasymmetric hydrogenation. The discovery and use of Hantzsch esters, design andsynthesis of novel catalyst, promoting the development of chiral catalysis.Asymmetrichydrogenation including the reduction of carbon carbon double bonds, carbonnitrogen double bonds, carbon oxygen double bonds and other unsaturatedbonds.Asymmetric hydrogenation of imines are introduced emphatically, the obtainedproduct present in natural products or can be used as intermediates to synthesizecomplex molecules.Besides,we take the previous9double axially chiral phosphorus imide catalystsapplied to the asymmetric hydrogenation of3-H indoles, and screenedthe catalysts,catalyst loading, reaction solvent and the reaction temperature, the optimum reaction conditions were obtained. This catalytic conditions (0℃, dichloromethane as thereaction solvent,1equivalents of3-H indoles,1.25equivalents of Hantzsch ester2a,1mol%VAPOL-BINOL cross derived phosphorus imide as catalyst,13kinds of3-Hindoleswere investigated. In the asymmetric hydrogenation of3-H indoles, the highestyield of the producst reached95%, the highest enantioselectivity reachd96%. Thereaction substrates were characterized by1H NMR and13C NMR, the products werecharacterized by1H NMR,13C NMR and high performance liquid chromate-graphy.To sum up, We take the previous9double axially chiral phosphorus imidecatalyst applied to the asymmetric hydrogenation of3-H indoles, and achieved betterresults. Through the adjustment and use of the catalysts, which makes we understandthe asymmetric hydrogenation of our chiral small molecules catalyzed3-H indolesmore deeply, and provide a reference for future research.