title: Preparation of cyclophanes by room-temperature ring-closing alkyne metathesis with imidazolin-2-iminato tungsten alkylidyne complexes.
abstract: Room-temperature ring-closing alkyne metathesis of 1,2-, 1,3-, and 1,4-bis(3-pentynyloxymethyl)benzenes has been investigated in the presence of catalytic amounts of an imidazolin-2-iminato tungsten alkylidyne complex. The m- and p-diynes selectively form the respective [10]metacyclophane or [10.10]paracyclophane, respectively, whereas a mixture of monomeric and dimeric cycloalkynes is obtained in the case of the o-diyne. DFT calculations reveal that the different selectivities can be attributed to the relative thermodynamic stability of the emerging cyclophanes.
authors.affiliation: Institut für Anorganische und Analytische Chemie, Technische Universität Carolo-Wilhelmina, Hagenring 30, D-38106 Braunschweig, Germany.
authors.forename: Stephan
authors.initials: S
authors.lastname: Beer
authors.forename: Kai
authors.initials: K
authors.lastname: Brandhorst
authors.forename: Jörg
authors.initials: J
authors.lastname: Grunenberg
authors.forename: Cristian G
authors.initials: CG
authors.lastname: Hrib
authors.forename: Peter G
authors.initials: PG
authors.lastname: Jones
authors.forename: Matthias
authors.initials: M
authors.lastname: Tamm