Synthesis and structural characterisation of two novel diastereoisomeric naproxen appended beta-cyclodextrin derivatives

The condensation reaction of 6-deoxy-6-amino(2-aminoethyl)-cyclomaltoheptaose (beta-CyDen) and racemic [(R,S)-2(6-methoxy-2-naphthyl) propanoic acid] (R,S-naproxen) affords two new diastereoisomeric naproxen-appended beta-cyclodextrin derivatives. The structural analysis of these two beta-CyD derivatives, undertaken by combined use of circular dichroism (CD) and 1D or 2D NMR techniques, shows that the naphthalene ring of the naproxen is included in the CyD cavity in both derivatives. The CD spectra are consistent with an axial complexation model, moreover, the self-inclusion mode is further corroborated by H-1 NMR ROESY spectra which also suggest the orientation of the naphthyl moiety in the cavity of both the diastereoisomers.