Chiral recognition of Schiff bases by N-15 NMR spectroscopy in the presence of a dirhodium complex. Deuterium isotope effect on N-15 chemical shift of the optically active Schiff bases and their dirhodium tetracarboxylate adducts

摘要

Optically active Schiff bases, derivatives of ortho-hydroxyaldehydes and their adducts with dirhodium tetracarboxylate complexes have been studied by N-15 NMR spectroscopy. The position of the equilibrium of Schiff bases, as well as their adducts, has been established on the basis of measurements of deuterium isotope effects on N-15 chemical shifts. At the equilibrium state, the formation of the adducts with dirhodium complexes shifted the proton-transfer equilibrium towards the NH-form. Copyright (C) 2008 John Wiley & Sons, Ltd.