title: Building complex carbon skeletons with ethynyl[2.2]paracyclophanes.
abstract: Ethynyl[2.2]paracyclophanes are shown to be useful substrates for the preparation of complex, highly unsaturated carbon frameworks. Thus both the pseudo-geminal- 2 and the pseudo-ortho-diethynylcyclophane 4 can be dimerized by Glaser coupling to the respective dimers 9/10 and 11/12. Whereas the former isomer pair could not be separated so far, the latter provided the pure diastereomers after extensive column chromatography/recrystallization. Isomer 11 is chiral and could be separated on a column impregnated with cellulose tris(3,5-dimethylphenyl)carbamate. The bridge-extended cyclophane precursor 18 furnished the ring-enlarged cyclophanes 19 and 20 on Glaser-Hay coupling. Cross-coupling of 4 and the planar building block 1,2-diethynylbenzene (1) yielded the chiral hetero dimer 22 as the main product. An attempt to prepare the biphenylenophane 27 from the triacetylene 24 by CpCo(CO)2-catalyzed cycloisomerization resulted in the formation of the cyclobutadiene Co-complex 26. Besides by their usual spectroscopic and analytical data, the new cyclophanes 11, 12, 19, 20, 22, and 26 were characterized by X-ray structural analysis.
authors.affiliation: Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.
authors.forename: Ina
authors.initials: I
authors.lastname: Dix
authors.affiliation: Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.
authors.forename: Lidija
authors.initials: L
authors.lastname: Bondarenko
authors.affiliation: Institut für Anorganische und Analytische Chemie, Technische Universität Braunschweig, Postfach 3329, D-38106 Braunschweig, Germany.
authors.forename: Peter G
authors.initials: PG
authors.lastname: Jones
authors.affiliation: Organisch-Chemisches Institut der Universität Heidelberg Im Neuenheimer Feld 270, D-69120 Heidelberg, Germany.
authors.forename: Thomas
authors.initials: T
authors.lastname: Oeser
authors.affiliation: Institut für Organische Chemie, Technische Universität Braunschweig, Hagenring 30, D-38106 Braunschweig, Germany.
authors.forename: Henning
authors.initials: H
authors.lastname: Hopf
keywords: Glaser coupling; X-ray analysis; carbon-rich molecules; complex carbon scaffolds; cyclophanes; multibridged cyclophanes