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The Asymmetric Henry Reaction And Asymmetric Aza-henry Reaction Catalyzed By Chiral β-Amino Alcohols And Their Derivatives

Posted on:2011-07-24Degree:MasterType:Thesis
Country:ChinaCandidate:H NiFull Text:PDF
GTID:2121330338977647Subject:Organic Chemistry
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Asymmetric synthesis has become a hot field in modern organic synthesis. Henry reaction and Aza-Henry reaction is important C-C bond forming reaction, and the product isβ-nitroalcohol andβ-nitroamine respectively. These resulting products are useful chemical intermediate. Theβ-nitroalcohol is able to be further transfirnations involving the newly formedβ-nitroalkanol functionality, such as amine, nitroalkene, and nitro-containing carbonyl compound. Theβ-nitroamine can be transformed to theα-aminoacid orβ-diamine compound.The asymmetric Henry reaction and asymmetric Aza-Henry reaction have great significance and value because theβ-nitroalcohol andβ-nitroamine is the intermediate of many medicines or natural products. The amino alcohol can be an efficient ligand and catalyze the enantioselective reaction, such as asymmetric epoxidation, asymmetric Michael addition, CBS reaction, asymmetric aldol reaction, asymmetric Mannich reaction and asymmetric Henry reaction in the presence of Lewis acid. We have prepared 12 chiralβ-amino alcohol ligands from L-phenylalanine methyl ester hydrochloride in a simplified way and used them as chiral catalysts in the asymmetric Henry reaction and asymmetric Aza-Henry reaction.This thesis mainly focuses on the following three aspects:1. Synthesis of chiralβ-amino alcohol1) The L-phenylalaninol was prepared from L-phenylalanine methyl ester hydrochloride by reduction with NaBH4. Then a series of chiralβ-amino alcohol derived from L-phenylalaninol was synthesized through aldehyde condensation and reduction. The structures of these chiralβ-amino alcohols have been characterized by MS, IR, 1H NMR and 13C NMR.2) The chiral 1,1-disubstituent L-phenylalaninols were prepared with L-phenylalanine methyl ester hydrochloride by Griganard reaction. Then 5 chiralβ-amino alcohols were obtained by aldehyde condensation and reduction. 2 chiralβ- amide alcohols were synthesized from 1,1-disubstituent L-phenylalaninols with acyl chlorides.2. Application of chiralβ-amino alcohols in the catalytic asymmetric Henry reactionThe complexes of chiralβ-amino alcohols derived from L-phenylalaninol with CuCl have been used as catalysts in the asymmetric Henry reaction to test the catalytic activities and enantioselectivities. The reactions underwent the optimized condition, but to our regret, there are only moderate yields and low ees.3. Application of chiralβ-amino alcohols in the catalytic asymmetric Aza-Henry reaction Total 20 chiralβ-amino alcohols have been used as ligands for the asymmetric Aza-Henry reaction of imine and nitromethane. After the riddling of ligands, copper salts and solvents, the enantiomeric excess of Aza-Henry reaction product was up to 85.7%.
Keywords/Search Tags:chiralβ-amino alcohol, asymmetric catalysis, Henry reaction, Aza-Henry reaction
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