- Br?nsted Acid-Catalyzed Carbonyl-Olefin Metathesis: Synthesis of Phenanthrenes via Phosphomolybdic Acid as a Catalyst
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Compared with the impressive achievements of catalytic carbonyl-olefin metathesis (CCOM) mediated by Lewis acid catalysts, exploration of the CCOM through Br?nsted acid-catalyzed approaches remains quite challenging. Herein, we disclose a synthetic protocol for the construction of a valuable polycycle scaffold through the CCOM with the inexpensive, nontoxic phosphomolybdic acid as a catalyst. The current annulations could realize carbonyl-olefin, carbonyl-alcohol, and acetal-alcohol in situ CCOM reactions and feature mild reaction conditions, simple manipulation, and scalability, making this strategy a promising alternative to the Lewis acid-catalyzed COM reaction.
- Chen, Yi,Liu, Di,Wang, Rui,Xu, Li,Tan, Jingyao,Shu, Mao,Tian, Lingfeng,Jin, Yuan,Zhang, Xiaoke,Lin, Zhihua
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supporting information
p. 351 - 362
(2022/01/03)
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- Modular Design of Fluorescent Dibenzo- and Naphtho-Fluoranthenes: Structural Rearrangements and Electronic Properties
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A library of 12 dibenzo- and naphtho-fluoranthene polycyclic aromatic hydrocarbons (PAHs) with MW = 302 (C24H14) was synthesized via a Pd-catalyzed fluoranthene ring-closing reaction. By understanding the various modes by which the palladium migrates during the transformation, structural rearrangements were bypassed, obtaining pure PAHs in high yields. Spectroscopic and electrochemical characterization demonstrated the profound diversity in the electronic structures between isomers. Highlighting the significant differences in emission of visible light, this library of PAHs will enable their standardization for toxicological assessment and potential use as optoelectronic materials.
- Mohammad-Pour, Gavin S.,Ly, Richard T.,Fairchild, David C.,Burnstine-Townley, Alex,Vazquez-Molina, Demetrius A.,Trieu, Khang D.,Campiglia, Andres D.,Harper, James K.,Uribe-Romo, Fernando J.
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supporting information
p. 8036 - 8053
(2018/05/31)
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- Isomerization of 7-oxabenzonorbornadienes into naphthols catalyzed by [RuCl2(CO)3]2
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(Chemical Equation Presented) Ruthenium-catalyzed isomerization of 7-oxanorbornadienes into naphthols was investigated. Among the various ruthenium catalysts tested, [RuCl2(CO)3]2 gave the highest yields in the isomerizati
- Ballantine, Melissa,Menard, Michelle L.,Tam, William
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supporting information; experimental part
p. 7570 - 7573
(2009/12/28)
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- Selective palladium-catalyzed cocyclotrimerization of arynes with dimethyl acetylenedicarboxylate: A versatile method for the synthesis of polycyclic aromatic hydrocarbons
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Benzyne (1a) and the substituted derivatives 4,5-difluorobenzyne (1b) and 3-methoxybenzyne (2) undergo chemoselective palladium-catalyzed [2 + 2 + 2]-cocyclotrimerization with dimethyl acetylenedicarboxylate (DMAD) to afford the corresponding phenanthrenes s and/or naphthalenes. The major products are phenanthrenes if Pd(PPh3)4 is used as the catalyst, naphthalenes if Pd2(dba)3 is used. When the method is applied to polycyclic arynes 3-6, which are generated from the corresponding o-trimethylsilylaryl triflates, the same reactivity pattern is observed: the reaction can be selectively directed either toward the cocyclization of one molecule of aryne and two molecules of alkyne or to the reaction of two molecules of aryne with one molecule of alkyne, by appropriate choice of the palladium catalyst. The synthesis of polycyclic aromatic compounds 33-39 using this methodology is reported.
- Pena,Perez,Guitian,Castedo
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p. 6944 - 6950
(2007/10/03)
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- Stereochemical and Mechanistic Aspects of Sulphoxide, Epoxide, Arene Oxide, and Phenol Formation by Photochemical Oxygen Atom Transfer from Aza-aromatic N-Oxides
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Stereoselectivity and relative yields are determined for the sulphoxide formation resulting from the u.v. irradiation of a range of aza-aromatic N-oxides in the presence of cyclic thioethers.A comparison is made with the results of oxidation by oxaziridines and by mono-oxygenase enzymes present in the fungus Aspergillus niger.The photochemical oxidation results are consistent with a transition state involving an oxaziridine intermediate where partial bonding of the oxygen atom to the ring nitrogen atom is maintained during the oxygen transfer process.Photolysis of aza-aromatic N-oxides in the presence of cis- and trans-olefins yields epoxides. cis-4-Methylpent-2-ene yielded both cis and trans-epoxides in almost equal proportions indicating that the oxygen atom addition to a carbon-carbon bond in this system is non-concerted.The photochemically induced oxygenation of perdeuteriated aromatic substrates provides no evidence for direct insertion of an oxygen atom into an aromatic carbon-hydrogen bond.Addition of an oxygen atom to form an epoxide (arene oxide) intermediate in this system is evidenced by the NIH shift in a wide range of aromatic substrates, and by the detection of arene oxide intermediates (and their isomeric phenols) from naphthalene and phenanthrene.
- Akhtar, M. Naseem,Boyd, Derek R.,Neill, John D.,Jerina, Donald M.
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p. 1693 - 1699
(2007/10/02)
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