title: [12]Annulynes.
abstract: Only one isomer of o-benzyne ([6]annulyne or 1,2-didehydrobenzene) exists, but the dehydro analogue of the "ring-opened double benzene", [12]annulyne, was generated in several isomeric forms. 1,5-Hexadiyne undergoes self-condensation in the presence of potassium tert-butoxide to yield two isomers of [12]annulyne (3,11-di-trans-[12]annulyne and 5,9-di-trans-[12]annulyne), both of which exhibit a weak paratropic ring current in their 1H NMR spectra and are oxygen sensitive. They can be reduced to their respective dianions, which are diatropic. A third isomer (3,9-di-trans-[12]annulyne) was generated via the complete dehydrohalogenation of hexabromocyclododecene and found to be much less stable but can be tamed via one- or two-electron reduction. A tight association of the cation (K+) with the p(y)-orbitals within the alkyne moiety results in an unusually low-field resonance for an adjacent external proton.
authors.affiliation: Department of Chemistry, Illinois State University, Normal, Illinois 61790-4160, USA.
authors.forename: Matthew N
authors.initials: MN
authors.lastname: Gard
authors.forename: Matthew K
authors.initials: MK
authors.lastname: Kiesewetter
authors.forename: Richard C
authors.initials: RC
authors.lastname: Reiter
authors.forename: Cheryl D
authors.initials: CD
authors.lastname: Stevenson