190773-33-2Relevant academic research and scientific papers
Direct catalytic asymmetric Mannich reactions of malonates and β-keto esters
Marigo, Mauro,Kjaersgaard, Anne,Juhl, Karsten,Gathergood, Nicholas,Jorgensen, Karl Anker
, p. 2359 - 2367 (2003)
The first catalytic asymmetric direct Mannich reaction of malonates and β-keto esters has been developed. Malonates react with an activated N-tosyl-α-imino ester catalyzed by chiral tert-butyl-bisoxazoline/Cu(OTf)2 to give the Mannich adducts in high yields and with up to 96% ee. These reactions create a chiral quaternary carbon center and it is demonstrated that this new direct Mannich reactions provides for example a new synthetic procedure for the formation of optically active β-carboxylic ester α-amino acid derivatives. A series of different β-keto esters with various ester substituents has been screened as substrates for the catalytic asymmetric direct Mannich reaction and it was found that the best results in terms of yield, diastereo- and enantioselectivity were obtained when tert-butyl esters of β-keto esters were used as the substrate. The reaction of different β-keto tert-butyl esters with the N-tosyl-α-imi-no ester gave the Mannich adducts in high yields, diastereo- and enantioselectivities (up to 95% ee) in the presence of chiral tert-butyl-bisoxazoline/Cu(OTf)2 as the catalyst. To expand the synthetic utility of this direct Mannich reaction a diastereoselective decarboxylation reaction was developed for the Mannich adducts leading to a new synthetic approach to attractive optically active β-keto α-amino acid derivatives. Based on the stereochemical outcome of the reactions, various approaches of the N-tosyl-α-imino ester to the chiral bisoxazoline/CuII-substrate intermediate are discussed.
Synthesis, characterization and biological activity of Cu(II) chelates with some amino acid derivatives
Nandi, M. M.,Choudhury, J.,Tarat, S.
, p. 288 - 291 (2007/10/02)
The complexing behaviour of seventeen amino acid derivatives towards Cu(II) has been studied.Complexes of the types Cu(RH)*xH2O, Cu(RH).Cu(OH)2*xH2O and Cu(R'H)2*yH2O have been prepared and characterized by IR, ESR, electronic spectral, magnetic moment and analytical data.On the basis of differences and direction of the shifts in the IR frequencies of vas OCO and vs OCO modes and ESR spectra, bonding modes of carboxylate group have been established.Biological activitu of complexes is more than that of the free metal ion and the ligands.
