Aldose epimerization by Ni(II): effect of ether-containing alkylenediamine ligands
摘要:
Several N-substituted ethylenediamine (en) Ni(II) derivatives containing ether linkages were prepared in order to study the effect of ligand structure on C-2 epimerization of aldohexoses. The reagent consisted of a Ni(II)-alkylenediamine derivative in methanol. The presence of ether linkages in the ligand increased the solubility of the complexes, and resulted in an increase in the rate of epimerization. Epimerization occured rapidly under mild conditions, and the same equilibrium point was reached regardless of whether the reaction was started from glucose or mannose. Among the ligands studied, N,N'-dialkylethyl-enediamine was the most active in C-2 epimerization.