Asymmetric 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
| Autor: | Hiroyuki Konno, Yoshinori Tokairin, Yuhei Shigeno, Gerd-Volker Röschenthaler, Jianlin Han, Hiroki Moriwaki, Vadim A. Soloshonok |
|---|---|
| Rok vydání: | 2020 |
| Předmět: |
Hydrogen
asymmetric synthesis chemistry.chemical_element Ni(II)-complexes 010402 general chemistry 01 natural sciences Medicinal chemistry lcsh:Chemistry chemistry.chemical_compound Dehydroalanine fluorine Chlorine Schiff base Full Paper 010405 organic chemistry tailor-made amino acids Enantioselective synthesis Diastereomer General Chemistry Full Papers 0104 chemical sciences lcsh:QD1-999 chemistry Fluorine Schiff bases Derivative (chemistry) |
| Zdroj: | ChemistryOpen, Vol 9, Iss 1, Pp 93-96 (2020) ChemistryOpen |
| ISSN: | 2191-1363 |
| DOI: | 10.1002/open.201900343 |
| Popis: | Four differently substituted chiral Ni(II)‐complexes of dehydroalanine Schiff base were prepared and reacted with BrCF2COOEt/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)(2S)/(S)(2R) 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. The secret is in the structure! An asymmetric Cu‐promoted Michael addition reaction between chiral Schiff base Ni(II)‐complexes and BrCF2COOEt is developed providing an easy method for the synthesis of (S)‐4,4‐difluoroglutamic acid. |
| Databáze: | OpenAIRE |
| Externí odkaz: |
|