256-81-5Relevant articles and documents
Blum,Biger
, p. 1825 (1970)
Laser Flash Photolysis Studies of Dibenzosuberenyl Cations and Radical Cations
Johnston, L. J.,Lobaugh, J.,Wintgens, V.
, p. 7370 - 7374 (1989)
A variety of dibenzosuberenyl systems have been investigated by laser flash photolysis.Excitation of the parent alcohol, 5-dibenzosuberenol, in trifluoroethanol yields the corresponding carbocation via heterolysis of the C-OH bond.The carbocation shows a long-lived (>100 μs) absorption at 525 nm with a second band at 390 nm, is readily quenched by nucleophiles (kq(azide) = 1.1 * 1E9 M-1 s-1), and fluoresces with a lifetime of 35 ns.In other solvents, the transient phenomena are dominated by the formation of the radical cation via a two-photon process.Both dibenzosuberene and 5-phenyl-5-dibenzosuberenol also yield radical cations in a variety of polar solvents.The radical cations show absorption spectra with maxima at 470 nm and a broad band in the 700-nm region, have lifetimes in oxygenated solutions of > 1.5 μs, and react with a variety of nucleophiles.Their identity has been confirmed on the basis of their independent generation with the electron-transfer sensitizers chloranil and 1,4-dicyanonaphthalene and by reaction with 1,2,4-trimethoxybenzene.
Pomerantz,M.,Fink,R.
, p. 2788 - 2790 (1977)
Herkstroeter,McClure
, p. 4522 (1968)
Synthesis and characterization of ion pairs between alkaline metal ions and anionic anti-aromatic and aromatic hydrocarbons with π-Conjugated central seven- And eight-membered rings
Bloch, Jan,Dey, Subal,Gianetti, Thomas L.,Grützmacher, Hansj?rg,Kradolfer, Stefan,Mougel, Victor,Ostendorf, Detlev
, (2020/10/27)
The synthesis, isolation and full characterization of ion pairs between alkaline metal ions (Li+, Na+, K+) and mono-anions and dianions obtained from 5H-dibenzo[a,d]cycloheptenyl (C15H11 = trop) is reported. According to Nuclear Magnetic Resonance (NMR) spectroscopy, single crystal X-ray analysis and Density Functional Theory (DFT) calculations, the trop- and trop2?? anions show anti-aromatic properties which are dependent on the counter cation M+ and solvent molecules serving as co-ligands. For comparison, the disodium and dipotassium salt of the dianion of dibenzo[a,e]cyclooctatetraene (C16H12 = dbcot) were prepared, which show classical aromatic character. A d8-Rh(I) complex of trop? was prepared and the structure shows a distortion of the C15H11 ligand into a conjugated 10π -benzo pentadienide unit—to which the Rh(I) center is coordinated—and an aromatic 6π electron benzo group which is non-coordinated. Electron transfer reactions between neutral and anionic trop and dbcot species show that the anti-aromatic compounds obtained from trop are significantly stronger reductants.
Flow-vacuum pyrolysis of dibenzocycloheptane derivatives on zeolites catalysts. IV
Istrati, Daniela,Parvulescu, Luminitza,Popescu, Angela,Mihaiescu, Dan,Badea, Florin
scheme or table, p. 711 - 714 (2011/10/02)
The pyrolysis of 10,11-dihydro-5H-dibenzo[a,d]cicloheptadien-5-ol (4) and of 5H-dibenzo[a,d]cycloheptatrien-5-ol (5) in flowvacuum conditions (advanced vacuum, inert atmosphere) on zeolites at 300°C is presented. The reaction products were identified by GC/MS using authentic samples and a reaction mechanisms involving cationic species as intermediates were proposed. A comparison with the pyrolysis of the same compounds performed in FVP conditions on quartz is presented.
The first efficient synthesis and optical resolution of monosubstituted cyclotribenzylenes
Schmuck, Carsten,Wienand, Wolfgang
, p. 655 - 663 (2007/10/03)
A new and high yielding synthetic route to monosubstituted cyclotribenzylenes 6 via the cyclocondensation of benzene with a suitably monosubstituted diol 20, obtained from ozonolysis of the corresponding dibenzosuberene precursor 19, was developed for the first time! The dibenzosuberene itself could be readily prepared in large quantities from inexpensive starting materials in five steps. Using this synthetic approach, a mono bromosubstituted cyclotribenzylene 12a was synthesized on large scale. Another four monosubstituted cyclotribenzylenes 21-24 were also prepared either via bromine/lithium exchange followed by subsequent quenching with external electrophiles or a copper mediated reaction with cyanide. These molecules adopt a rigid crown conformation as shown by X-ray analysis and temperature dependent NMR studies. The barrier to inversion is quite high, requiring temperatures well above 120°C before inversion takes place. Futhermore, such monosubstituted cyclotribenzylenes are planar chiral and after optical resolution, using HPLC, we were able to obtain the first planar chiral Cl-symmetric cyclotribenzylenes in form of the optically pure enantiomers of 12a, the CD spectra of which are exact mirror images over the entire spectral range.
