CuI Catalytic Amino Acids To Promote The Ullmann Class Carbon - Carbon Bond Cross-coupling Reaction

The transition metal-catalyzed cross-coupling reactions to form sp~2 C-C or C-hetero atom bonds have received considerable attention in the past decades.In comparison with Pd and Ni,copper is a cheaper metal with lower toxicity.Asymmetric carbon-carbon bond cross-coupling reactions,especially the construction of all-carbon quaternary stereo center, are an important part of organic synthesis and still full of challenge.In this dissertation we wish to report our recent investigations on the cross-coupling reactions of aryl halides with activated methylene compounds under the catalysis of CuI and amino acids,and the asymmetricα-arylation reaction of 2-substitutedβ-keto esters.In the chapter 2 of this dissertation,we reported the cross-coupling reaction of aryl halides with activated methylene compounds under the catalysis of CuI and amino acid. Using the coupling of 4-iodoanisole with ethyl acetoacetate as a model reaction,we explored the optimized conditions.These conditions were then tested by using several electron-rich or electron-deficient aryl iodides,β-keto esters and diethyl malonates.It was found that most of them were successfully converted to the corresponding products in good to excellent yields.Further studies indicated that aryl bromides under the similar reaction conditions gave moderate to good yields of coupling products.Electron-rich aryl iodides or bromides showed higher reactivities in comparison with electron-deficient ones.We proposed that this reaction might go through the oxidative addition/reductive elimination mechanism.In the chapter 3 of this dissertation,we studied the asymmetricα-arylation reaction of 2-substitutedβ-keto esters under the catalysis of CuI and amino acid.After screening substrates,reactants,solvents,ligands and bases,we found that when 2-iodotrifluoroacetanilides were used as the substrates,t-butyl 2-methylacetoacetates as a coupling partner,CuI as the catalyst,L-4-hydroxyproline as the ligand,NaOH as a base, DMF as the solvent and small amount of water as additive,the reactions can be carried out at -45℃to give the corresponding coupling products in good yields and good to excellent enatioselectivity.By converting a coupling product into a known oxindole compound in two steps,we concluded that the absolute configuration of our coupling products is S.We also proposed that this reaction might go through the oxidative addition/reductive elimination mechanism.