3416-63-5Relevant academic research and scientific papers
Reduction of Carbon Dioxide to Give Unstable Carbon Oxides. Electron Transfer from the Reduction Products of Carbon Dioxide with Benzoin Carbanion to Triphenylcarbenium Ion
Akiyama, Fuminori
, p. 873 - 875 (1994)
Reaction of the redunction products of carbon dioxide (CO2) by benzoin carbanion with triphenylcarbenium ion (1) gave 1-(diphenylmethyl)-4-(triphenylmethyl)benzene (2) which was considered to be electron transfer product from the reduction products of CO2
Unusual formation and helicity induction in a para-amino-substituted trityl chromophore: a cautionary note
Janiak, Agnieszka,?ciebura, Jacek,Bendzińska-Berus, Wioletta,Grajewski, Jakub,Rychlewska, Urszula,Gawroński, Jacek
, p. 811 - 814 (2016)
O- and N-trityl derivatives Ph3C?-X-R?of chiral alcohols (X?=?O) and amines (X?=?NH) are known to produce strong and stereochemically predictable Cotton effects in the Electronic Circular Dichroism (ECD) spectra due to the
Facile Rearrangement of the 6,11-Diphenyldibenzo[b,f][1,4]diazocine Skeleton into a Substituted 2-(2-Aminophenyl)-1,3-diphenylisoindole via Anomalous Carbolithiation or Hydrolithiation: Corroboration of Operative SET Processes
Eisch, John J.,Liu, Wei,Zhu, Lisheng,Rheingold, Arnold L.
, p. 7384 - 7394 (2015/11/25)
The starting 6,11-diphenyldibenzo[b,f][1,4]diazocine has been individually treated with R-Li reagents in THF, where R = AlH4, PhCH2, Ph2CH, Ph3C, CH3, CH3(CH2)3, C6H5 or Ph-C≡C, to learn whether an expected 1,2- or 1,4-addition would cleanly occur. Contrary to such an assumption based on nucleophilic attack, this [1,4]diazocine with PhCH2Li yielded only the enantiomers of (4b,11R)-11-benzyl-4b,11-diphenyl-4b,11-dihydro-5H-benzo[4,5]imidazo[2,1-a]isoindole; with Ph2CHLi yielded 2-[1-(4-benzhydrylphenyl)-phenyl-2H-isoindol-2-yl]analine; and with LiAlH4 2-(2-aminophenyl)-1,3-diphenylisoindole. Finally, individual reactions of the [1,4]diazocine with CH3Li, nBuLi or PhLi gave 4-5 inseparable products, instead of any simple 1,2 or 1,4 adduct. The anomalous carbolithiations and hydrolithiation observed are irreconcilable with a nucleophilic mechanism but in excellent accord with a SET radical-anion pathway.
6,12-Diphenyldibenzo[b,f][1,5]diazocine as an electron-capture agent: Efficient mechanistic probe for SET processes and reagent for the oxidative dimerization of benzylic organometallics
Eisch, John J.,Yu, Kun,Rheingold, Arnold L.
experimental part, p. 3165 - 3171 (2012/06/30)
In the present study, 6,12-diphenyldibenzo[b,f][1,5]diazocine, which X-ray diffraction measurements have now shown to possess a tub-shaped, eight-membered central ring, has been treated with sodium or lithium metal at 25 °C in THF, in an attempt to form the planar, Hueckel-aromatic dianion by the addition of two electrons to the central diazocine. Hydrolysis of such an aromatic dianion should have led to the isomeric 5,12- or 5,6-dihydro derivative of the original diazocine. In actuality, the only product obtained quantitatively upon hydrolytic workup was the interesting quadricyclic transannular reduction product, 4b,9b-diphenyl-4b,5,9b,10-tetrahydroindolo[3,2-b]indole, whose 3D structure has now been confirmed by X-ray crystallography and 13C NMR spectroscopy. Preferential SET transannular reduction of the diazocine to yield the quadricyclic indolo[3,2-b]indole dianion, rather than the planar, Hueckel-aromatic anion, is ascribed to the transannular electronic stabilization operative in the tub-shaped diazocine radical-anion. The quantitative generation of the indolo[3,2-b]indole dianion can be employed for the oxidative dimerization of the organic groups in benzylic lithium reagents. Thus treating one equivalent of the diazocine with two equivalents of benzyllithium, benzhydryllithium, or trityllithium yields quantitatively bibenzyl, 1,1,2,2-tetraphenylethane, or (4-benzhydrylphenyl)triphenylmethane, respectively. This oxidative dimerization is potentially of practical preparative scope, since the hydrolysis byproduct, the indolo[3,2-b]indole, is conveniently reconverted into the starting diazocine reagent by oxidation with chromium trioxide in acetic acid. The formation of the indolo[3,2-b]indole as a byproduct in the carbometalation of the diazocine by various RLi and Grignard reagents offers a clue as to the SET mechanism of carbometalation. Copyright
Diphenylpyridylmethyl radicals. Part 1. Synthesis, dimerization and ENDOR spectroscopy of diphenyl(2-, 3- or 4-pyridyl)methyl radicals; bond dissociation enthalpies of their dimers
Tzerpos, Nikolaos I.,Zarkadis, Antonios K.,Kreher, Richard P.,Repas, Liesel,Lehnig, Manfred
, p. 755 - 762 (2007/10/02)
ortho-ortho hydrogen van der Waals repulsions are the origin of the propeller shape of the triphenylmethyl radical and the main reason for the low bond dissociation enthalpy (BDH) of its dimer 1 (44.8 J mol-1).In order to reduce these steric repulsions (eliminating some aromatic hydrogens), diphenyl(2-, 3- or 4-pyridyl)methyl radicals 2-4 were prepared through reductive dehalogenation of the corresponding triarylchloromethanes 2-4a with silver in benzene.They form α,p-dimers 2-4e exclusively through the pyridine ring.ENDOR spectroscopy shows that the structure of the radicals, does not deviate substantially from that of the parent radical, PH3C-radical.In contrast, the BDH values of the dimers (measured using EPR spectroscopy) show strengthening of the central C-C bond in 2e (88.7 kJ mol-1) and 3e (90.0 kJ mol-2) and a silimar value for 4e (46.4 kJ mol-1) with respect to the trityl dimer 1.This is a consequence of the ground state stabilization of the dimers 2-4e due to relief of strain (elimination of ring hydrogens), whereas in the case of 4e, this stabilization is probably compensated by the formation of a weaker C-N bond with respect to the C-C bond.The above dimers undergo easy 1,5-H-rearrangement, autocatalysed by the basic pyridyl groups themselves.
Mechanism of reduction of trityl halides by lithium dialkylamide bases
Newcomb, Martin,Varick, Thomas R.,Goh, Swee-Hock
, p. 5186 - 5193 (2007/10/02)
Trityl chloride (TCl) and bromide are reduced by hindered lithium dialkylamide bases in THF to give predominantly triphenylmethane and a small amount of trityl dimer. Rate constants for the reduction of TCl by lithium diisopropylamide and lithium tert-butylethylamide in THF at -78 ?C have been measured; the reactions are first order in monomeric base and in trityl chloride. Inter- and intramolecular kinetic isotope effect studies employing β-deuterium substituted bases and substituent effect studies coupled with other kinetic information were used to formulate a scheme for the reactions. The reactions proceed by a rapid predissociation of the trityl halide to form an ion pair containing the trityl-THF oxonium cation followed by diffusion controlled electron transfer (ET) from the monomeric form of the base to the trityl-THF oxonium ion. The radical pair thus formed reacts by fast, highly regioselective β-hydrogen atom transfer from the aminyl radical to the methine carbon of the trityl radical to give triphenylmethane. Radical escape from the cage is a minor competing process. An outer-sphere ET process is energetically acceptable, but an inner-sphere process appears to be more likely.
Arene Hydrides, 8. - SET vs. Nucleophilic Attack in Reactions of α-Bromoisobutyrophenone with Carbanions. Fragmentation of the Anion of Tetrahydrobianthracene
Werry, Juergen,Stamm, Helmut,Sommer, Andreas
, p. 1553 - 1562 (2007/10/02)
SET is the main reaction pathway between α-bromoisobutyrophenone (1) and the carbanions 7a-j- of diarylmethanes or disubstituted acetonitriles: 7- 7. + e and e + 1 Br- PhCOCMe2. (3).Main secon
The Reaction of Triphenylmethyl Halides with Tributylphosphine and Tributylamine in Apolar Solvents
Huszthy, Peter,Izso, (nee Gergacz) Gyoengyi,Lempert, Karoly,Kajtar-Peredy, Maria,Gyoer, Miklos,et al.
, p. 1513 - 1520 (2007/10/02)
Triphenylmethyl bromide (1a) and chloride (1b) react with tributylphosphine and tributylamine in aromatic hydrocarbons by single electron transfer.The triphenylmethyl radicals produced (which may be detected by e.s.r. spectroscopy) abstract hydrogen from the solvent or the radical cations of the reagents to give triphenylmethane (1c), and are trapped by oxygen to give triphenylmethylperoxy radicals and subsequently benzophenone, triphenylmethanol (1d), and phenol.Tributylphosphine and tributylamine may act as hydrogen donors in the hydrogen-transfer processes involved in the formation of these oxygenation products.The halides (1a, b) and tributylphosphine furnish, in the absence of oxygen, in addition to triphenylmethane (1c) the tele substitution products (2a) and (2b), respectively.There is some evidence that the phosphonium salt (2a) is formed by an S'ET process, i.e. out-of-cage recombination of triphenylmethyl radicals and tributylphosphine radical cations or tributylphosphine.
Sterically Hindered Free Radicals, XV The First Unsymmetrical Dimer from Two Different Stable Radicals: 3-(tert-Butylphenylmethylene)-6-(triphenylmethyl)-1,4-cyclohexadiene from tert-Butyldiphenylmethyl and Triphenylmethyl
Neumann, Wilhelm P.,Stapel, Ralf
, p. 2006 - 2012 (2007/10/02)
The quinonoid title compound 6 is formed in an equilibrium to 95percent and can be isolated, when the two title radicals 1 and 3 are generated in solution.The reason for this is the sterically less strained position of the bulky tBu group at the sp2
The Ambident Reactivity of Triphenylmethyl Radicals in Hydrogen-abstraction Reactions and the Mechanism of the Base-catalysed Rearrangement of (Diphenylmethylene)cyclohexadienes (a Type of Semibenzene) into Triphenylmethane
Huszthy, Peter,Lempert, Karoly,Simig, Gyula,Tamas, Jozsef,Hegedus-Vajda, Judit,Toth, Gabor
, p. 491 - 498 (2007/10/02)
Thermolysis of tri(phenyl)(phenylazo)methane (2) in non-deuteriated 2,2-dimethoxypropane in the presence of non-deuteriated sodium methoxide furnishes, among other products, mixtures of the deuteriated analogues of triphenylmethane (1c) and of deuteriated analogues of (p-biphenylyl)diphenylmethane (3a).The former was shown to be a mixture of the hexadecadeuterio derivative (6c) and the isomeric monoprotiopentadecadeuterio derivatives (6a and b), while the latter proved to be a mixture of the pentaprotio derivative (3d) and the isomeric hexaprotio derivatives (3b and c).The formation of compound (6b) proves the ambident reactivity of triphenylmethyl radicals in hydrogen-abstraction reactions, while the observed ratio of compounds (6a and b) indicates the rearrangements of the intermediate semibenzenes (7) and (8) to be multistep conducted-tour rearrangements (Scheme 1).
