Open AccessAsymmetric Synthesis of 4,4‐(Difluoro)glutamic Acid via Chiral Ni(II)‐Complexes of Dehydroalanine Schiff Bases. Effect of the Chiral Ligands Structure on the Stereochemical Outcome
Author(s) -
Tokairin Yoshinori,
Shigeno Yuhei,
Han Jianlin,
Röschenthaler GerdVolker,
Konno Hiroyuki,
Moriwaki Hiroki,
Soloshonok Vadim A.
Publication year - 2020
Publication title -
chemistryopen
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.644
H-Index - 29
ISSN - 2191-1363
DOI - 10.1002/open.201900343
Subject(s) - dehydroalanine , chemistry , diastereomer , schiff base , chirality (physics) , stereochemistry , combinatorial chemistry , derivative (finance) , medicinal chemistry , amino acid , biochemistry , chiral symmetry breaking , physics , quantum mechanics , nambu–jona lasinio model , quark , financial economics , economics
Abstract Four differently substituted chiral Ni(II)‐complexes of dehydroalanine Schiff base were prepared and reacted with BrCF 2 COOEt/Cu under the standard reaction conditions. The observed diastereoselectivity was found to depend on the degree and pattern of chlorine substitution for hydrogen in the structure of the dehydroalanine complexes. The unsubstituted complex gave the ratio of diastereomers ( S )(2 S )/( S )(2 R ) of 66/34. On the other hand, introduction of chlorine atoms in the strategic positions on the chiral ligands allowed to achieve a practically attractive diastereoselectivity of (∼98.5/1.5). Diastereomerically pure major product was disassembled to prepare 9‐fluorenylmethyloxycarbonyl (Fmoc) derivative of ( S )‐4,4‐difluoroglutamic acid.