- The Trityl Cation Embedded into a [7]Helicene-Like Backbone: Preparation and Application as a Lewis Acid Catalyst
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The synthesis of a helically chiral carbenium ion is reported. The new motif is essentially a trityl cation embedded into a [7]helicene-like framework. The key step in its preparation establishes the π-extended fluorenone system in one step by an unprecedented palladium-catalyzed carbonylative annulation of a 4,4′-biphenanthryl-3,3′-diyl precursor. The racemic form of the new carbon Lewis acid was found to catalyze a representative set of reactions typically promoted by the trityl cation.
- Gross, Benjamin M.,Oestreich, Martin
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p. 2512 - 2516
(2021/03/22)
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- TRANSITION METAL COMPOUND FOR OLEFIN POLYMERIZATION CATALYST, OLEFIN POLYMERIZATION CATALYST COMPRISING SAME AND POLYOLEFIN POLYMERIZED USING SAME
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Provided is a transition metal compound, represented by chemical formula 1, for an olefin polymerization catalyst. The details of chemical formula 1 are the same as those defined in the specification.
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Paragraph 0052-0053
(2021/06/11)
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- Design and synthesis of new stable fluorenyl-based radicals
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Organic neutral radicals have long fascinated chemists with a fundamental understanding of structure-reactivity relationships in organic reactions and with applications as new functional materials. However, the elusive nature of these radicals makes the synthesis, isolation, and characterization very challenging. In this work, the synthesis of three long-lived, fluorenyl-based radicals are reported. The geometry and electronic structures of these radicals were systematically investigated with a combination of various experimental methods, besides density functional theory (DFT) calculations, which include X-ray crystallographic analysis, electron spin resonance (ESR), electron nuclear double resonance (ENDOR), cyclic voltammetry, and UV-vis-NIR measurements. Their half-life periods (τ1/2) in air-saturated solution under ambient conditions were also determined. Surprisingly, all three radicals showed remarkable stabilities: τ1/2 = 7, 3.5, and 43 days.
- Tian, Yi,Uchida, Kazuyuki,Kurata, Hiroyuki,Hirao, Yasukazu,Nishiuchi, Tomohiko,Kubo, Takashi
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p. 12784 - 12793
(2015/02/19)
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- Reversible Friedel-Crafts acyl rearrangements of planar polycyclic aromatic ketones: Dibenzofluorenones
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Dibenzofluorenones undergo reversible Friedel-Crafts acyl rearrangements in PPA at elevated temperatures. The Friedel-Crafts acyl rearrangements of 13H-dibenzo[a,i]fluoren-13-one (DBaiF) yield both 13H-dibenzo[a,h]fluoren-13-one (DBahF) and 12H-dibenzo[b,h]fluoren-12-one (DBbhF). DBahF and DBbhF undergo reversible mutual isomerizations, and their ratio depends on the reaction conditions. The O-protonate DBahFH+ plays a pivotal role in the proposed mechanism of the reversible Friedel-Crafts acyl rearrangements. DBahFH+ may undergo proton migration to give two isomeric σ-complexes: σ-13aH-DBahF+ and σ-12aH-DBahF +, leading, via the respective naphthyl naphthoylium ions βCOβN-βN+ and αCOβN-βN+ to O-protonates DBbhFH+ and DBaiFH+, respectively. The regioselectivity of the rearrangement is expressed by the preferred intramolecular beta-electrophilic attack in βCOβN-βN+ and by the preferred alpha-electrophilic attack in αCOβN-βN +, which indicates a thermodynamic control. The proposed mechanism is supported by the results of the DFT calculations of the dibenzofluorenones, their O-protonates, their σ-complexes and their corresponding naphthyl naphthoylium ions at B3LYP/6-311++G(d,p). DBahF and DBaiF are the kinetically controlled products of the Friedel-Crafts acyl rearrangement, while DBbhF is the thermodynamically controlled product. The aromaticity/antiaromaticity notions in dibenzofluorenones and their O-protonates, estimated by calculated HOMA and NICS indices, are discussed. The Royal Society of Chemistry 2013.
- Mala'Bi, Tahani,Pogodin, Sergey,Cohen, Shmuel,Agranat, Israel
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p. 21797 - 21810
(2013/11/06)
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- DIBENZO[C,G]FLUORENE COMPOUND AND ORGANIC LIGHT-EMITTING DEVICE USING SAME
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An organic light-emitting device is provided which efficiently emits light with high brightness and has durability. The organic light-emitting device includes a dibenzo[c,g]fluorene compound having two dibenzo[c,g]fluorene skeletons, and has an organic compound layer containing the dibenzo[c,g]fluorene compound.
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Page/Page column 11; 40; 41-42
(2010/06/11)
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- DIBENZO[c,g]FLUORENE COMPOUND AND AN ORGANIC LIGHT-EMITTING DEVICE USING THE SAME
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An organic light-emitting device which has high emission efficiency and high durability even at low drive voltage is provided. An organic light-emitting device including an anode, a cathode, and an organic compound layer which is interposed between the anode and the cathode, wherein the organic compound layer include at least one dibenzo[c,g]fluorene compound represented by the following General Formula (1).
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Page/Page column 56-57
(2009/12/23)
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