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C_2-Symmetric Chiral Diamine Ligands For Enantiomeric Recognition Of Amino Acid Esters And Mandelic Acid By Proton Nmr Titration Method, Hayri̇ye Aral, Tarik Aral, Mehmet Çolak, Berri̇n Zi̇yadanoğullari, Recep Zi̇yadanoğullari
C_2-Symmetric Chiral Diamine Ligands For Enantiomeric Recognition Of Amino Acid Esters And Mandelic Acid By Proton Nmr Titration Method, Hayri̇ye Aral, Tarik Aral, Mehmet Çolak, Berri̇n Zi̇yadanoğullari, Recep Zi̇yadanoğullari
Turkish Journal of Chemistry
Two novel C_2-symmetric chiral diamines containing \alpha -phenylethyl and \alpha -(1-naphthyl)ethyl chiral subunits were prepared with quantitative yields. Enantiomeric recognition properties of these simple structured diamine ligands towards D- and L-amino acid esters and D- and L-mandelic acid were examined by the ^1H NMR titration method. These ligands exhibited strong complexation (with K_f up to 2481 M^{-1}) and good enantioselectivity (up to K_L/K_D = 4.08) towards the mandelic acid enantiomers. The results show that simple structured and easily accessible acyclic C_2-symmetrical compounds can also be used for enantiomeric recognition of racemic amino acids and mandelic acid in addition to complex …
Asymmetric Synthesis Of \Alpha-(Heteroaryl)Alkylamines And \Alpha -Amino Acids Via Nucleophilic 1,2-Addition Of Lithiated Heterocycles To Aldehyde Samp-Hydrazones, Dieter Enders, Giuseppe Del Signore, Gerhard Raabe
Asymmetric Synthesis Of \Alpha-(Heteroaryl)Alkylamines And \Alpha -Amino Acids Via Nucleophilic 1,2-Addition Of Lithiated Heterocycles To Aldehyde Samp-Hydrazones, Dieter Enders, Giuseppe Del Signore, Gerhard Raabe
Turkish Journal of Chemistry
The asymmetric synthesis of \alpha-(heteroaryl)alkylamines was accomplished by employing a diastereoselective nucleophilic 1,2-addition of lithiated aromatic heterocycles to aldehyde SAMP-hydrazones, followed by BH_3 . THF or SmI_2 promoted removal of the chiral auxiliary. The CBz or benzoyl-protected amines were obtained in good yields (40\%--78\%) and excellent enantiomeric excesses (ee = 88\%--99\%). The methodology can be applied to the synthesis of highly enantioenriched \alpha-amino acids (ee = 90\%--99\%).