title: Organometallic dehydro[14] annulenes containing Vollhardt's cyclobutadiene: are CpCo-complexed cyclobutadienes more aromatic then benzene?
abstract: Pd-catalyzed coupling of 1,2-diethynyl-3,4-(bistrimethylsilyl)cyclobutadienecyclopentadienylcobalt to a series of 1-iodo-2-(trimethylsilylethynyl)benzenes and 1-chloro-4-trimethylsilylbut-1-ene-3-yne is followed by desilylation with potassium carbonate. Cu(OAc)(2)-promoted oxidative ring closure leads to dehydro[14]annulenes and dehydro[14]benzoannulenes fused to a cyclobutadiene(cyclopentadienylcobalt) complex. Five of these fused dehydroannulenes were structurally characterized. (1)H NMR spectroscopy of the organometallic dehydro[14]annulenes incorporating the (bistrimethylsilyl)cyclobutadiene(cyclopentadienylcobalt) unit suggested that the aromaticity of the fused cyclobutadiene complex might be stronger than that of benzene according to the ring-current criterion.
authors.affiliation: Department of Chemistry and Biochemistry, The University of South Carolina, Columbia, South Carolina 29208, USA.
authors.forename: M
authors.initials: M
authors.lastname: Laskoski
authors.forename: M D
authors.initials: MD
authors.lastname: Smith
authors.forename: J G
authors.initials: JG
authors.lastname: Morton
authors.forename: U H
authors.initials: UH
authors.lastname: Bunz