Molecular structure of 3-(methoxycarbonyl) amino-beta-carboline, a selective antagonist of the sedative effects of diazepam

The X-ray crystal structure of 3-(methoxycarbonyl) amino-beta-carboline, a selective antagonist of the sedative effects of diazepam having a high affinity for the benzodiazepine receptor, has been determined. The results were compared with structural information obtained from this compound, both in the solid state and in dilute solution, by use of Fourier transform infrared spectroscopy. Its X-ray structure was also compared with those of two other active beta-carbolines, methyl beta-carboline-3-carboxylate and N-ethyl-3-carbamoyl-beta-carboline. The crystal packing characteristics of 3-(methoxycarbonyl) amino-beta-carboline differ from those of these two beta-carbolines in both the pattern of intermolecular hydrogen bonding and the quality of their pi-pi stacking interactions. The relevance this may have to the selective activity of 3-(methoxycarbonyl) amino-beta-carboline is discussed.