Evaluation of the equilibrium constants, chemical shifts and stoichiometries for reactions of lanthanide shift reagents containing β-diketones with carbohydrate derivatives

The interactions between lanthanide shift reagents containing β-diketone ligands and a number of methyl 2,3-anhydro-4,6-O-benzylidene-D-hexopyranosides have been investigated using NMR spectroscopy. Chemical shift data have been used to determine the stoichiometries of the reactions and to evaluate the equilibrium constants. Various models are evaluated. The data show that the carbohydrate moiety may be bound to the lanthanide shift reagent in either a monodentate or chelated fashion.