82704-15-2Relevant academic research and scientific papers
General Method of Diastereo- and Enantioselective Synthesis of β-Hydroxy-α-amino Acids by Condensation of Aldehydes and Ketones with Glycine
Belokon, Yuri N.,Bulychev, Alexander G.,Vitt, Sergei V.,Struchkov, Yuri T.,Batsanov, Andrei S.,et al.
, p. 4252 - 4259 (2007/10/02)
The condensation of formaldehyde with a Ni(II) complex of glicyne Schiff base with (S)-2-acetophenone (1) or (S)-2-benzophenone (2) in CH3OH at 25 deg C in the presence of Et3N yields (S)-Ser with an enantiomeric excess (ee) of 80-90percent.The same reaction gives rise to (R)-Ser with an ee greater than 80percent in the presence of more than 0.2 N CH3ONa, α-(hydroxymethyl) serine being formed in negligible quantities.The reaction of benzaldehyde, 3,4-(methilenedioxy)benzaldehyde, and acetaldehyde with these Gly complexes in 0.2 N CH3ONa at 25 deg C yields β-hydroxy-α-amino acids: (R)-β-phenylserine, (R)-3,4-(methylenedioxy)-β-phenylserine, and (R)-threonine, respectively, with a threo/allo ratio ranging from 10:1 up to over 50:1 and ee more than 80percent.Condensation with acetone yields (R)-β-hydroxyvaline with an enantiomeric purity of 70percent.The enantiomerically pure β-hydroxy-α-amino acids can be obtained from pure diastereomers, isolated by chromatography on silica or Toyopearl HW-60.The initial reagents 1 and 2 were recovered with 60-98percent yield.The stereochemical mechanism of the reaction is discussed.
Asymmetric Synthesis of Threonine and Partial Resolution and Retroracemization of α-Amino Acids via Copper(II) Complexes of Their Schiff Bases with (S)-2-N-(N'-Benzylprolyl)aminobenzaldehyde and (S)-2-N-(N'-Benzylprolyl)aminoacetophenone. Crystal and Molecular Structure of a ...
Belokon', Yu. N.,Zel'tzer, I. E.,Bakhmutov, V. I.,Saporovskaya, M. B.,Ryzhov, M. G.,et al.
, p. 2010 - 2017 (2007/10/02)
The work described here is concerned with the search for universal chiral reagent for the asymmetric synthesis, resolution, and retroracemization of amino acids.Reaction of N-benzyl-(S)-proline with o-aminobenzaldehyde or o-aminoacetophenone has given (S)-2-N-(N'-benzylprolyl)aminobenzaldehyde ((S)-BPAB) or (S)-2-N-(N'-benzylprolyl)aminoacetophenone ((S)-BPAAPh).These chiral reagents have interacted with α-amino acids (aa) and Cu(II) ions to form complexes CuII and CuII in which Schiff bases (S)-BPAB-aa or (S)-BPAAPh-aa act as tetradentate ligands and coordinate the copper ion by the nitrogen atoms of the pyrrolidine fragment, the deprotonated amide group, and the amino acid fragment and by the oxygen atom of the carboxylate.Such a structure was supported by data on elemental analysis, the molecular weight measurements, and electron, IR, and CD spectra.It was finally confirmed by an X-ray diffraction analysis of CuII.One equivalent of (S)-BPAB has reacted with 2 equiv of (R,S)-aa and 2 equiv of Cu(II), having given preferential formation of copper complexes of Schiff bases with (S)-aa.After their extraction with chloroform the amino acid enriched with the R enantiomer remained in the aqueous solution.In this manner partial resolution of racemic amino acids (Ala, Nva, Phe, Val, Thr) has been carried out with enantiomeric purity 4-50percent. (S)-BPAB or (S)-BPAAPh treatment of a racemic amino acid in the presence of Cu(II) ions (reagents ratio 1:1:1) and CH3O- ions permits enantiomeric enrichment via conversion of the R into S enantiomer (retroracemization).Thus (S)-Ala, (S)-Nva, (S)-Leu, (S)-Val, (S)Phe, and (S)-PhGly of enantiomeric purity 36, 12, 22, 54, 42, and 35percent, respectively, were obtained from racemic samples.CH3O--catalyzed reaction of CuII or CuII with acetaldehyde has given rise to a mixture of diastereomeric complexes, which upon removal of Cu(II) by H2S gave (R)-threonine of 60percent or 97-100percent enantiomeric purity and the threo/allo ratio 6:1 or 19:1, respectively, and permitted recovery of an unchanged initial chiral reagent (S)-BPAB or (S)-BPAAPh.
(S)-o-N-(N-Benzylprolyl)aminobenzaldehyde and (S)-o-N-(N-Benzylprolyl)aminoacetophenone as Reagents for Asymmetric Synthesis of Threonine
Belokon, Yuuri N.,Zeltzer, Irina E.,Ryzhov, Michail G.,Saporovskaya, Marina B.,Bakhmutov, Vladimir I.,Belikov, Vasili M.
, p. 180 - 181 (2007/10/02)
Chiral aldehydes and ketones, derivatives of proline and piperidine-2-carboxylic acid have been synthesized and their Schiff bases with glycine form copper complexes which were hydroxyethylated with acetaldehyde; decomposition of the complexes obtained gave threonine with an optical purity of up to 97-100percent and with threo/allo ratios of up to 19 : 1, and the chiral reagents can be recovered and reused with no loss of optical purity of the threonine.
