ABSTRACT
These equilibria are fast on the NMR time-scale, and result in a single, timeaveraged spectrum. The diastereomeric complexes generally exhibit differences in the chemical shifts of the resonances of some of the protons or carbons of the sub strate that are in close proximity to the LSR. Reasons for these chemical shift dif ferences include possible geometry differences of the two diastereomeric complexes, and different binding constants due to unequal equilibrium constants (ATr , Ks), with the larger equilibrium constant leading to the larger binding con stant and concomitant larger chemical shifts. In general, the closer the chiral cen ter is to the functionality that complexes to the shift reagent, the greater the chances are for a successful resolution of diastereomeric complexes. Do realize that in practice not all the resonances in a pair of enantiomers will separate out. All that needs to be achieved, however, is adequate separation of any one signal such that accurate integration of the separated signals is possible.
