title: Topologically novel multiple rotaxanes and catenanes based on tetraurea calix[4]arenes.
abstract: Calix[4]arenes bearing at their wide rim four urea residues easily form hydrogen bonded dimeric capsules. This has been used to preorganise alkenyl functions attached to these urea groups for their controlled connection via metathesis reaction. Multimacrocyclic tetraurea derivatives are thus obtained in excellent yields via heterodimers which are formed exclusively with tetratosylurea derivatives. Heterodimerisation of such bis- and tetraloop tetraureas leads analogously to multicatenanes, or to rotaxanes by stoppering. Huge macrocycles are detached from tetraloop derivatives by cleavage of the urea function.
authors.affiliation: Fachbereich Chemie, Pharmazie und Geowissenschaften, Abteilung Lehramt Chemie, Johannes Gutenberg-Universität, Duesbergweg 10-14, D-55099 Mainz, Germany.
authors.forename: Anca
authors.initials: A
authors.lastname: Bogdan
authors.forename: Yuliya
authors.initials: Y
authors.lastname: Rudzevich
authors.forename: Myroslav O
authors.initials: MO
authors.lastname: Vysotsky
authors.forename: Volker
authors.initials: V
authors.lastname: Böhmer