Imidazole-based Potential Bi- and Tridentate Nitrogen Ligands: Synthesis, Characterization and Application in Asymmetric Catalysis
作者:Roman Sívek、Filip Bureš、Oldřich Pytela、Jiří Kulhánek
DOI:10.3390/molecules13092326
日期:——
Twelve new imidazole-based potential bi- and tridentate ligands were synthesized and characterized. Whereas in the first series the α-amino acid and imidazole moieties were linked by an amino bond, in the second series the tridentate ligands, containing two imidazole groups, were separated by an amide bond. The first series was obtained by the reductive amination of 2-phenylimidazole-4-carboxaldehyde with α-amino acid esters. The tridentate ligands were prepared from 2-phenylimidazole-4-carboxylic acid and chiral amines. In the Henry reaction, the amines were revealed as a more reactive species than the less nucleophilic amides, however the enantiomeric excesses were generally poor.
合成并表征了十二种新的基于咪唑的潜在双齿和三齿配体。第一系列中,α-氨基酸和咪唑部分通过氨基键连接,而在第二系列中,含有两个咪唑基团的三齿配体通过酰胺键分隔。第一系列是通过2-苯基咪唑-4-醛与α-氨基酸酯的还原胺化反应获得的。三齿配体则是由2-苯基咪唑-4-羧酸和手性胺制备而成。在亨利反应中,胺显示出比亲核性较低的酰胺更具反应性,然而,通常情况下,外消旋过量较低。