Asymmetric Bromokinetic Resolution Catalyzed By Chiral Phosphoric Acid

Chiral phosphoric acid catalyst is a kind of organic catalysis,does not Convtain metal,will not cause pollution to the environment,and is beneficial to environmental protection.Chiral phosphoric acid belongs to Bronsted acid.The chiral phosphoric acid catalyst Convtains P=O and hydroxyl.Among them,the phosphorous-oxygen double bond is the property of Lewis base and the hydroxyl is the property of Bronsted acid.Moreover,the catalysis of chiral phosphoric acid catalysts is dependent on these two site reactions.In addition,the chiral phosphoric acid catalyst can catalyze carbon-carbon double bonds,carbon-nitrogen bonds and carbon-heteroatom bonds,and can make stereoselective reactions that are difficult to Convtrol,and can have a higher stereoselective effect.The structure of chiral phosphoric acid catalyst Convtains many skeletons,which are generally divided into:BINOL,H₈-BINOL,C₈-BINOL,SPINOL,VAPOL,TADDOL,and p-cycloalkane.Generally speaking,the advantages of chiral phosphoric acid catalysts are as follows:easy to prepare,modular in nature,two enantiomers of the catalyst can be used,relatively strong and suitable acidity to capture electrophilic components,a dual function Characteristic,it has both Bronsted acidic sites and Bronsted basic sites as well as variable adjacent substituents to provide steric and electronic influences.This topic uses R-SPINOL-TRIP chiral spirocyclic phosphoric acid catalyst,the temperature is-78?,the solvent is ultra-dry toluene,and the suitability of the substrate is explored.It is found that when the phenyl group Convtains an electron-donating group,the kinetic decomposition is The effect of points is good.When it Convtains electron-withdrawing groups,the effect of kinetic resolution is relatively poor.Therefore,some electron-donating group-Convtaining substrates are used to carry out the reaction when expanding the substrate.Moreover,this topic is only suitable for the substrates of quaternary carbon quinoline derivatives,and the reaction effect on quinoline derivatives Convtaining tertiary carbon is relatively poor.In addition,in the case of multi-rings such as phenanthridine derivatives,this The effect of the reaction is not very good.In summary,this paper developed a chiral spiro catalyst R-SPINOL-TRIP to catalyze the kinetic resolution of para-bromo quinoline derivatives.The first use of bromine,asymmetric synthesis under the action of a catalyst,and under the action of a chiral phosphoric acid catalyst,a single para position with bromine,but no bromination at the ortho position.However,in the background reaction of racemization,both ortho and para-brominated products were formed,and the yields were similar.It shows that the chiral phosphoric acid catalyst can Convtrol the steric selectivity in this reaction,which is also one of the characteristics of the reaction.In addition,the subject studied the kinetic resolution of bromine at the para-position of quinoline,and obtained the product of the S Convfiguration and the raw material of the R Convfiguration,and the steric selectivity of the kinetic resolution was high.Because the para position is halogen,bromine can be Convverted into boronic ester,and reactions such as Suzuki cross-coupling can be performed.