DETERMINATION OF ENANTIOMERIC PURITY OF CHIRAL LACTONES - GENERAL-METHOD USING NUCLEAR MAGNETIC-RESONANCE

A general method is described for determining enantiomeric purities of chiral lactones, regardless of their ring size. The approach involves treatment of a lactone with methyllithium, followed by NMR examination of the diol produced in the presence of a chiral shift reagent such as Eu(tfc)3. The method is broadly applicable to a wide range of variously substituted γ, δ, and e-lactones. Its accuracy for enantiomeric excess determinations is ±3%. This has been confirmed using selected optically active lactones of established optical purities. © 1979, American Chemical Society. All rights reserved.