The Preparation Of Chiral Hydroxy Compounds Through Chiral Phosphoric Acid Catalyzed Ring-opening Reactions

Chiral hydroxy compounds are ubiquitous in nature,and the preparation of chiral hydroxy compounds has been a hot research area for organic chemists.Asymmetric catalysis is the one of most effective ways to obtain chiral compounds.Organocatalysis has emerged as an important way in the field of asymmetric catalysis.Particularly,chiral phosphoric acid(CPA)catalysis has been found to be a valuable strategy recently.Asymmetric ring opening reactions can build functionalized linear or cyclic molecules with one or more chiral centers on adjacent or distal carbon atoms efficiently.In this paper,we describe the recent progress of asymmetric ring-opening reactions catalyzed by chiral phosphoric acid,and focus on our research on preparation of chiral alcohols via ring-opening reactions catalyzed by CPA.This dissertation includes three parts.In the first part,the progress of asymmetric ring-opening reactions catalyzed by chiral Phosphoric acid is presented.In the second part,We discribed the desymmetrization of meso-1,3-diols by chiral phosphoric acid catalyzed oxidation of meso-1,3-diol benzylidene acetals.Using chiral phosphoric acid as catalyst,dimethyldioxirane(DMDO)as oxidant,acetone as solvent,and using 3,5-di-tert-butyl-4-methoxyphenyl(DTBM)as protecting group for reaction at 0?,Chiral diols with good yield and excellent enantioselectivity are obtained.Oxidation of acetal by DMDO forms a criegee type intermediate,and enantioselectivity is achieved by the chiral phosphoric acid via asymmetric proton transfer.This method also has a good tolerance for substrates of alkyl and oxygen-containing substrates.The last part,kinetic resolution of caprolactone catalyzed by chiral phosphoric acid was studied.Chiral phosphoric acid as catalyst,toluene as solvent,and benzyl alcohol as nucleophile at 0?.The primary alcohol attacks the lactone to form the criegee type intermediate,the chiral phosphoric acid differentiates the racemate during proton transfer and then undergoes enantioselective ring opening.Affording caprolactone and the product in moderate enantioselectivity.A wide range of substrates were tolerated under the optimal conditions.