67064-62-4Relevant academic research and scientific papers
A regionally selective hydrogenation method for chromium-catalyzed thick cyclic aromatic hydrocarbons and olefins based on magnesium-activated ligands
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Paragraph 0020, (2022/01/10)
The present invention relates to the field of hydrogenation, specifically to a chromium-activated complex cyclic aromatic hydrocarbons and olefins promoted by magnesium-activated ligands regionally selective hydrogenation method, which is based on the in situ reduction strategy of magnesium, with biimides as ligands, CrCl2 as catalyst precursors, to construct an efficient low-costchromium hydrogenation system, under mild conditions, to achieve unilateral cyclic hydrogenation of thick ring aromatic hydrocarbons and high-selective hydrogenation of olefins. The system of the present invention is suitable for a variety of substrates of fused cyclic aromatic hydrocarbons, such as tetraphenyl, benzoanthracene, pentabenzo and alfalfa and the like. This provides a simple and efficient strategy and pathway for the synthesis of partially saturated thick cyclic aromatic hydrocarbon compounds.
Chromium- and Cobalt-Catalyzed, Regiocontrolled Hydrogenation of Polycyclic Aromatic Hydrocarbons: A Combined Experimental and Theoretical Study
Han, Bo,Ma, Pengchen,Cong, Xuefeng,Chen, Hui,Zeng, Xiaoming
supporting information, p. 9018 - 9026 (2019/06/13)
Polycyclic aromatic hydrocarbons are difficult substrates for hydrogenation because of the thermodynamic stability caused by aromaticity. We report here the first chromium- and cobalt-catalyzed, regiocontrolled hydrogenation of polycyclic aromatic hydrocarbons at ambient temperature. These reactions were promoted by low-cost chromium or cobalt salts combined with diimino/carbene ligand and methylmagnesium bromide and are characterized by high regioselectivity and expanded substrate scope that includes tetracene, tetraphene, pentacene, and perylene, which have rarely been reduced. The approach provides a cost-effective catalytic protocol for hydrogenation, is scalable, and can be utilized in the synthesis of tetrabromo- and carboxyl-substituted motifs through functionalization of the hydrogenation product. The systematic theoretical mechanistic modelings suggest that low-valent Cr and Co monohydride species, most likely from zerovalent transition metals, are capable of mediating these hydrogenations of fused PAHs.
Method for selectively catalyzing and hydrogenating polycyclic aromatic hydrocarbon by virtue of chromium salt/methyl magnesium bromide
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Paragraph 0028; 0029; 0030; 0031; 0032; 0138; 0139-0142, (2017/10/13)
The invention discloses a method for selectively catalyzing and hydrogenating polycyclic aromatic hydrocarbon by virtue of chromium salt/methyl magnesium bromide. The method comprises the step of carrying out normal temperature stirring reaction on polycyclic aromatic hydrocarbon in an H2 atmosphere by taking chromium salt and methyl magnesium bromide as catalysts, a diimine compound as a ligand and tetrahydrofuran as a solvent, so as to obtain a hydrogenation product. Based on the regulation and control of the diimine ligand and the synergetic catalysis of chromium salt and methyl magnesium bromide, the high-selectivity hydrocarbon of polycyclic aromatic hydrocarbon is realized at the room temperature; and the method has the advantages of low cost, mild reaction conditions, high selectivity and the like, high-temperature harsh conditions are avoided, and precious metal catalysts with relatively high costs are not used. The method is applicable to the hydrogenation of different 2-site, 9-site and 10-site substituted anthracene derivatives and other polycyclic aromatic hydrocarbon substrates.
Nickel-catalyzed cocyclotrimerization of arynes with diynes; a novel method for synthesis of naphthalene derivatives
Hsieh, Jen-Chieh,Cheng, Chien-Hong
, p. 2459 - 2461 (2007/10/03)
The NiBr2(dppe)-Zn system effectively catalyzes the [2 + 2 + 2] cocyclotrimerization of arynes with diynes, leading to substituted naphthalene derivatives in moderate to good yields. This cocyclotrimerization reaction shows excellent tolerance of functional groups and leads to products of 5- to 7-membered fused-ring sizes. The Royal Society of Chemistry 2005.
Photochemical cycloaromatization reactions of ortho-dialkynylarenes: A new class of DNA photocleaving agents
Funk,Young,Williams,Flanagan,Cecil
, p. 3291 - 3292 (2007/10/03)
We are intrigued by the possibility of consolidating the functional elements of the enediyne anticancer antibiotics, thereby simplifying the task of synthesizing potential chemotherapeutic agents which operate by DNA cleavage pathways. Thus, it was envisaged that certain polycyclic ortho-dialkynylarenes would intercalate into DNA and, moreover, the planar π systems might be further exploited by facilitating photochemical, as opposed to thermal, cycloaromatization/cleavage reactions. We report herein on the viability of this photochemical transformation and the resultant new class of DNA photocleaving agents, whose binding and photoactive domains are consolidated, and which generate two reactive sites for subsequent ribose hydrogen atom abstraction(s).
A Photoannulation Route to Naphthalenes from Cyclic Ketones
Olsen, Robert J.,Minniear, John C.,Overton, W. Mack,Sherrick, John M.
, p. 989 - 991 (2007/10/02)
A three-step annulation of cyclic ketones has been developed.Aldol condensation with an aromatic aldehyde followed by Wittig olefination produces a 1,3-diene, which undergoes oxidative photocyclization to produce a naphthalene derivative.Ketone ring sizes of C5 to C8 were annulated successfully.The sequence was also applied successfully to three methyl-substituted derivatives and one polycyclic case.
Cycloaromatization of α-oxoketene dithioacetals and β-oxodithioacetals with benzyl-,1-(naphthylmethyl) and 2-(naphthylmethyl)magnesium halides: Synthesis of condensed polynuclear aromatic hydrocarbons
Srinivasa Rao,Balu, Maliakel P.,Ila, Hiriyakkanavar,Junjappa, Hiriyakkanavar
, p. 3499 - 3510 (2007/10/02)
An efficient route for the synthesis of substituted naphthalenes, phenanthrenes and other polynuclear aromatic hydrocarbons has been developed. The methodology involves 1,2- (or sequential 1,4- and 1,2-) addition of either benzyl, 1-(naphthylmethyl) or 2-(naphthylmethyl) magnesium halides to α-oxoketene dithioacetals or β-oxodithioacetals followed by borontrifluoride etherate catalyzed cycloaromatization of the resulting carbinols.
Reduction of Polycyclic Arenes by BH Boranes, III. Partial Hydrogenation: From Anthracene to Coronene
Yalpani, Mohamed,Koester, Roland
, p. 719 - 724 (2007/10/02)
Tetrapropyldiboran(6) (TPDB) katalysiert die Hydrierung polycyclischer Arene unter Wasserstoff-Druck bei bei 200 deg C.In einigen Faellen koennen sehr hohe Ausbeuten an Hydroarenen erzielt werden .Neben unterschiedlichen kleinen Mengen an Perhydroarenen bilden sich nach langer Reaktionszeit aus saemtlichen Arenen auch C-C-Spaltungsprodukte.
Photochemistry of Stilbenes. 8. Eliminative Photocyclization of o-Methoxystilbenes
Mallory, Frank B.,Rudolph, M. Jonathan,Oh, Soon M.
, p. 4619 - 4626 (2007/10/02)
The synthetic value of the eliminative photocyclization of o-methoxystilbenes to give phenanthrenes with loss of the element of methanol has been enhanced by the use of tert-butyl alcohol as the solvent and sulfuric acid as a catalyst. 2-Methoxy-5-X-stilbenes and 2-methoxy-3-X-stilbenes undergo this photoreaction to produce the corresponding 2-X-phenanthrenes and 4-X-phenanthrenes, respectively.This regioselective photochemical route to these particular types of substituted phenanthrenes represents an improvement synthetically over the well-known oxidative photocyclization method with meta-substituted stilbenes, from which approximately 1:1 mixtures of 2-substituted and 4-substituted phenanthrenes usually are obtained.An attempt to extend the scope of this eliminative photocyclization method to the synthesis of benzanthracene by the ultraviolet irradiation of 3-methoxy-2-styrylnaphthalene was not successful, but this synthetic objective was achieved in an alternative way by the eliminative photocyclization of 5,6,7,8-tetrahydro-3-methoxy-2-styrylnaphthalene followed by oxidation of the resulting 8,9,10,11-tetrahydrobenzanthracene with DDQ.
Regioselective Catalytic Hydrogenation of Polycyclic Aromatic Hydrocarbons under Mild Conditions
Fu, Peter P.,Lee, Hong M.,Harvey, Ronald G.
, p. 2797 - 2803 (2007/10/02)
Hydrogenation of polynuclear hydrocarbons over a palladium catalyst at low pressure and ambient temperature affords regiospecifically the corresponding K-region dihydroarenes, while analogous reactions over a platinum catalyst take place regioselectively on terminal rings to provide the related tetrahydroarenes.Hydrogenation over palladium of phenanthrene, benzanthracene, 7,12-dimethylbenzanthracene, benzpyrene, 3-methylcholanthrene, dibenzanthracene, and chrysene gave 9,10-dihydrophenanthrene, 5,6-dihydrobenzanthracene, 5,6-dihydro-7,12-dimethylbenzanthracene, 4,5-dihydrobenzopyrene, 11,12-dihydro-3-methylcholanthrene, 5,6-dihydrodibenzanthracene, and 5,6-dihydrochrysene, respectively (Table I).Hydrogenation over platinum of benzanthracene, 7-methylbenzanthracene, 12-methylbenzanthracene, 7,12-dimethylbenzanthracene, benzopyrene, chrysene, dibenzanthracene, 5,6-dihydrobenzanthracene, 5,6-dihydro-7,12-dimethylbenzanthracene, and 4,5-dihydrobenzopyrene furnished the corresponding terminal ring tetrahydroarenes (Table II).Partial hydrogenation beyond the dihydro stage in the presence of palladium was exhibited only by hydrocarbons with more than one K region.In these cases, the second stage of hydrogen addition was generally slower than the first, so that the extent of reaction was readily controllable.Hydrogenation was blocked by alkyl substitution in an otherwise susceptible ring, and regioselectivity was diminished or abolished by increased hydrogen pressure, prolonged reaction, or acidity.The mechanism of reaction over palladium is proposed to involve concerted hydrogen addition to the K region, the region of minimum bond delocalization energy, preceded by localized ? and/or ? complexes.Evidence is presented that hydrogenations over platinum do not involve initial addition to the K region followed by isomerization into the terminal ring.Instead, these reactions are suggested to involve addition of 2 mol of hydrogen via an intermediate ? complex to the terminal ring which affords the most thermodynamically favored tetrahydroarene product, i.e., that which requires the minimum amount of energy for its formation.
