title: Concomitant polymorphism in the stereoselective synthesis of a β-benzyl-β-hydroxyaspartate analogue.
abstract: Two concomitant polymorphs, (I) and (II), of a β-benzyl-β-hydroxyaspartate analogue [systematic name: dibenzyl 2-benzyl-2-hydroxy-3-(4-methylphenylsulfonamido)succinate], C(32)H(31)NO(7)S, crystallize from a mixture of ethyl acetate and cyclohexane at ambient temperature. The structure of (I) has triclinic (P-1) symmetry and that of (II) monoclinic (P2(1)/c) symmetry. Both crystal structures are made up of a stacking of homochiral racemic dimers (2S,3S and 2R,3R) which are internally connected by a similar R(2)(2)(9) hydrogen-bonding pattern consisting of intermolecular N-H...O and O-H...O hydrogen bonds. The centroid of the racemic dimer lies on an inversion centre. The main structural difference between the two polymorphs is the conformational orientation of two of the four aromatic rings present in the molecule. Polymorph (II) is found to be twinned by reticular merohedry with twin index 3 and twin fractions 0.854 (1) and 0.146 (1).
authors.affiliation: Laboratoire de Synthèse Organique Appliquée, Université d'Oran Es-Sénia, Département de Chimie, Oran, Algeria.
authors.forename: Sofiane
authors.initials: S
authors.lastname: Mekki
authors.forename: Valérie
authors.initials: V
authors.lastname: Rolland
authors.forename: Salima
authors.initials: S
authors.lastname: Bellahouel
authors.forename: Arie
authors.initials: A
authors.lastname: van der Lee
authors.forename: Marc
authors.initials: M
authors.lastname: Rolland
mesh_terms: D001224:Aspartic Acid / Q000031:analogs & derivatives* / Q000737:chemistry; D003460:Crystallization; D018360:Crystallography, X-Ray; D006860:Hydrogen Bonding; D008968:Molecular Conformation; D015394:Molecular Structure
chemical_list: C561506:beta-benzyl-beta-hydroxyaspartate; D001224:Aspartic Acid