Synthesis Of Chiral Tridentate Schiff-base Ligands And Their Application In Catalytic Asymmetric Henry Reaction

Catalytic asymmetric is a hot field in modern synthetic organicchemistry. Henry reaction is one of the classical C-C bond formingreactions. The resulting β-nitroalcohol products can be convenientlytransformed into many valuable intermediates, such as β-amino alcoholand nitroalkenes, which are important to the synthesis of pharmaceuticalsand nature compounds. However great progress have been made incatalytic asymmetric Henry reaction, some of these catalytic systemssuffer from certain limitations. Therefore, the design and development ofnovel chiral ligands is still in demand.Chiral tridentate Schiff-base is one of the promising ligands inasymmetric catalysis, which have been widely applied in manyasymmetric reactions. However, only a few studies used tridentate Schiffbase ligands in catalytic asymmetric Henry reaction. In this paper, a seriesof chiral tridentate Schiff-base ligands have been prepared and applied incatalytic asymmetric Henry reaction. This thesis mainly included thefollowing three parts:1. Recent development of asymmetric Henry reaction was reviewed. Different kinds of catalytic systems were classified in this paper.2. Synthesis of chiral tridentate schiff-base ligandsTreat the L-Phenylalanine methyl ester hydrochloride andL-Phenylglycine methyl ester hydrochloride with NaBH4or Grignardreagent give five kinds of chiral β-amino alcohols. Six kinds ofsubstituted salicylaldehyde were prepared from β-naphthol orsalicylaldehyde. Chiral β-amino alcohols and substituted salicylaldehydewere condensed in ethanol to give sixteen kinds of chiral tridentateschiff-base ligands. The structures of these ligands have beencharacterized by MS, IR,1H NMR and13C NMR.3. Asymmetric Henry reaction catalyzed by copper Complexes ofchiral tridentate schiff-basesThe chiral tridentate schiff-bases were applied in catalyticasymmetric Henry reaction of aldehyde with nitromethane. Differentreaction conditions were tested in this process. Under the optimalconditions, a variety of arylaldehydes were smoothly converted intocorresponding adducts with high yields (up to97%) and excellentenantioselectivities (up to96%ee).