Research On Desymmetrization Of Diols By Chiral Small Organic Molecule

Desymmetrization of diols by chiral small organic molecule is studied in this thesis which is composed of five parts:Part 1:Oxidative desymmetrization of 2-aryl-1,3-diols by chiral phosphoric acidDesymmetrization of 2-aryl-1,3-diols catalysed by chiral phosphoric acid via oxidative cleavage of benzylidene acetasl is reported.Chiral 2-aryl-1,3-diols could be obtained in high yield and excellent enantioselectivity.And mechanism of the reaction is studied by DFT calculation.Part 2:Desymmetrization of 2-nitro-1,3-diols by chiral phosphoric acidDesymmetrization of 2-nitro-1,3-diols by chiral phosphoric acid is reported.Chiral a-tertiary amine could be obtained with excellent yield and ee.Unnatural amino acids and natural products could be synthesized smoothly.Part 3:Desymmetrization of 2-alkyl-1,3-diols by chiral phosphoric acidA new protect group of acetal is designed via DFT calculation and used in oxidative desymmetrization of 2-alkyl-1,3-diols.Acyclic all-carbon quaternary centers could be constructed in high yields and ee.The enantioselective formal synthesis of Rhazinilam and Leucomidine B could be realized.Part 4:Desymmetrization of Carbonates by Chiral GuanidinesIn this part,desymmetrization of carbonates catalyzed by chiral guanidines is reported.The structure of guanidine is the key to enantioselectivity.And moderate enantioselectivity could be obtained when morpholine was used as nucleophile.Part 5:Reductive desymmetrization of acetalsIn this chapter,asymmetric reduction of acetals is studied,different kinds of Lewis acid are used as catalyst.The reaction has high reaction activity but the enantioselectivity is not well controlled.And the reaction is stilled in study.