title: Novel Redox-Active Cyclophanes Based on 3,3'-Biindolizines: Synthesis and Chirality.
abstract: The first compounds of a new series of redox-active cyclophanes were prepared by dehydrocyclization of bridged indolizines of type 1. The bridged dipyridino-compounds 2a and 2b obtained by reaction of 2 mol of lithiated alpha-picolines with dihalides were used as starting materials. Subsequent treatment of 2a,b with 2 mol of alpha-bromo ketones gave quaternary pyridinium halides. Ring closure in an alkaline medium (Chichibabin reaction) yielded the starting material for the synthesis of the macrocycles. Oxidative C-C coupling gave the diastereomeric cyclophanes of type 3. In all cases one pair of the enantiomers was obtained in excess. CV-investigations have shown that the main products are reversible redox systems. To clarify their conformations, compounds 3c, 3d/1, and3d/2 were subjected to X-ray analysis.
authors.affiliation: Institut für Angewandte Chemie Berlin-Adlershof, Abteilung Organische Synthese and Abteilung Analytik, Rudower Chaussee 5, D-12484 Berlin, Germany.
authors.forename: Helmut
authors.initials: H
authors.lastname: Sonnenschein
authors.forename: Thomas
authors.initials: T
authors.lastname: Kreher
authors.forename: Egon
authors.initials: E
authors.lastname: Gründemann
authors.forename: Ralph-Peter
authors.initials: RP
authors.lastname: Krüger
authors.forename: Annamarie
authors.initials: A
authors.lastname: Kunath
authors.forename: Volker
authors.initials: V
authors.lastname: Zabel