title: Chiral Hexahalogenated 4,4'-Bipyridines.
abstract: The preparation of 27 isomers of chiral hexahalogeno-4,4'-bipyridines by means of two complementary methods is described. The first one is convergent and based on the LDA-induced 4,4'-dimerization of trihalopyridines, whereas the second method is divergent and achieved through regioselective halogenation reactions of 4,4'-bipyridine-2,2'-diones. Iodine in 2,2'-positions of the 4,4'-bipyridines was introduced by a copper-catalyzed Finkelstein reaction (Buchwald procedure) performed on 2,2'-dibromo derivatives. Selected compounds of this new family of atropisomeric 4,4'-bipyridines were enantioseparated by high performance liquid chromatography on chiral stationary phases, and the absolute configurations of the separated enantiomers were assigned by using X-ray diffraction analysis. The latter revealed that various halogen bond types are responsible for crystal cohesion.
authors.affiliation: Institut de Chimie de Strasbourg, UMR 7177, Equipe LASYROC , 1 rue Blaise Pascal, BP 296 R8, 67008 Strasbourg Cedex, France.
authors.forename: V
authors.initials: V
authors.lastname: Mamane
authors.affiliation: Istituto di Chimica Biomolecolare ICB CNR - UOS di Sassari , Traversa La Crucca 3, Regione Baldinca, I-07100 Li Punti - Sassari, Italy.
authors.forename: P
authors.initials: P
authors.lastname: Peluso
authors.affiliation: Cristallographie, Résonance Magnétique et Modélisations (CRM2), UMR CNRS 7036, Université de Lorraine , BP 70239, Bd des Aiguillettes, 54506 Vandoeuvre-les-Nancy, France.
authors.forename: E
authors.initials: E
authors.lastname: Aubert
authors.affiliation: Dipartimento di Scienze Molecolari e Nanosistemi, Università Ca' Foscari di Venezia , I-30172 Mestre Venezia, Italy.
authors.forename: S
authors.initials: S
authors.lastname: Cossu
authors.affiliation: Institut de Chimie de Strasbourg, UMR 7177, Equipe LASYROC , 1 rue Blaise Pascal, BP 296 R8, 67008 Strasbourg Cedex, France.
authors.forename: P
authors.initials: P
authors.lastname: Pale