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Previous molecular modeling studies, in our laboratory, have shown that some esters of type RCOO(CH2) nC5H5N+Cl− are potentially active against Alzheimer's disease. We have also demonstrated that acridine, which has strong anticholinesterase activity appears to be a suitable R substituent. The main obstacle to the possible pharmaceutical application of these compounds is their limited solubility in water, which is due to the poor aqueous solubility of acridine itself (0.26 mM). Inclusion complexation with cyclodextrins may overcome this problem. Solubility diagrams and NMR spectroscopy were used to study the inclusion of acridine (Acr) within β‐cyclodextrin (βCD) and heptakis(2,6‐di‐O‐methyl)cyclomaltoheptose (DMβCD). A 1:1 complex was formed for the Acr–βCD system and both 1:1 and 2:1 complexes for the Acr–DMβCD system (apparent Ka 215 ± 20 and 1150 ± 100 M −1, respectively). Data from 1H NMR studies corrected the assignment of the acridine H1, H8 and H4, H5 protons in D2O, which have been erroneously assigned in previous publications. 1H spin–lattice relaxation times T1 measured with selective, non‐selective and null inversion characterize the dynamics of the inclusion complexes. Geometric features of the host–guest inclusion complexes were inferred from intermolecular dipolar interactions obtained by 2D adiabatic off‐resonance ROESY experiments. A more detailed picture of the structure of the inclusion complexes was obtained by combining NMR structural data and molecular modeling (docking, dynamics under NMR constraints and energy calculations). Copyright © 2002 John Wiley & Sons, Ltd.

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The proline‐catalyzed intramolecular aldol reaction of the diketone (Ia) followed by dehydration leads to product (II).

A metabolite extracted from maize culture was identified as cyclonerodiol. Its 1H and 13C NMR spectra have been fully analysed, and some literature assignments have been reversed.

: Since the discovery of the multi-drug resistance (MDR) phenotype, reversant agents of various origins and structures have been extensively studied. In the present work, two series of related 2,4,6-tris(amino)-striazines with di †erent MDR potential1 were studied by 15N NMR spectroscopy. The 15N nucleus allows an easy identiÐcation of two protonation sites and an estimation of the electronic e †ects. 15N was further found to be well suited to demonstrate the occurrence at room temperature of restricted rotation around the ArÈN bonds between the amino substituents and the s-triazine ring and to measure the rotational barriers. Crystal structures were determined by x-ray analysis of the compounds at various stages of protonation. The e †ects of the protonation at the sterically less hindered nitrogen of the triazine, detected by the NMR study, were conÐrmed in the solid-state structures. In the crystals, the orientation of the NÈH and NÈC bonds of the NHallyl substituent with respect to the triazine ring does not depend on the protonation state and corresponds to one of the conformations postulated in solution.

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