title: Crystallographic studies and semi-empirical MNDO calculations on quisqualic acid and its analogues: systems containing unusual pyramidal heterocyclic ring nitrogens.
abstract: X-ray crystallographic studies on synthetic DL-quisqualic acid and the corresponding carbon analogue have revealed pyramidal and almost planar geometries respectively for the ring nitrogen atoms carrying the alkyl side chain. Semi-empirical molecular orbital calculations on methyl-substituted model systems predict ring geometries in close agreement with experimentally observed data. The calculated energy barriers between the two enantiomeric forms (invertomers) of the oxadiazolidine systems along with some physical data would suggest that such forms are rapidly interconverting.
authors.affiliation: Department of Pharmaceutical Sciences, University of Nottingham, U.K.
authors.forename: D E
authors.initials: DE
authors.lastname: Jackson
authors.forename: B W
authors.initials: BW
authors.lastname: Bycroft
authors.forename: T J
authors.initials: TJ
authors.lastname: King
mesh_terms: D003198:Computer Simulation; D006571:Heterocyclic Compounds; D008958:Models, Molecular; D008968:Molecular Conformation; D010069:Oxadiazoles; D016318:Quisqualic Acid; D013329:Structure-Activity Relationship; D014961:X-Ray Diffraction
chemical_list: D006571:Heterocyclic Compounds; D010069:Oxadiazoles; D016318:Quisqualic Acid