A NUCLEAR-MAGNETIC-RESONANCE STUDY OF THE DIASTEREOISOMER COMPLEXES FORMED BETWEEN A TERGURIDE DERIVATIVE AND NAPROXEN

H-1 NMR (600 MHz) measurements of chemical shift changes were made in acidified (DCI) CD3OD/D2O 1:9 v/v equimolar solutions of (S)- and (R,S )-6-methoxy-alpha-methyl-2-naphthaleneacetic acid (naproxen) in the pr esence of 1-(3-aminopropyl)(5R, 8S, 10R)-terguride (AMP-TER). The most significant bonding interactions concurring to the formation of diast ereoisomer complexes are seen as chemical shifts in proximity to the p ositively charged nitrogen N(6)-CH3 and of H(12), H(13), H(14) protons of the ergoline skeleton, both the adducts having an electrostatic te rm and different pi-pi stabilizing interactions. Chemical shift data e xclude any contribution of the aminopropyl chain to the chiral recogni tion mechanism. These findings provide an experimental basis for the e nantiodiscriminative process accounting for the observed chromatograph ic resolutions of arylcarboxylic acids on chiral stationary phases der ived from AMP-TER, (C) 1994 Wiley-Liss, Inc.