- Electrochemical Decarboxylative Cyclization of α-Amino-Oxy Acids to Access Phenanthridine Derivatives
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Phenanthridines are a class of useful heterocycles in the field of drug development. In this work, a method via electrochemical decarboxylative cyclization of α-amino-oxy acids to access phenanthridine derivatives was developed. This reaction proceeded th
- Zhan, Yanling,Dai, Changhui,Zhu, Zitong,Liu, Ping,Sun, Peipei
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supporting information
(2022/02/07)
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- Gold Catalysts Can Generate Nitrone Intermediates from a Nitrosoarene/Alkene Mixture, Enabling Two Distinct Catalytic Reactions: A Nitroso-Activated Cycloheptatriene/Benzylidene Rearrangement
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Gold-catalyzed reactions of cycloheptatrienes with nitrosoarenes yield nitrone derivatives efficiently. This reaction sequence enables us to develop gold-catalyzed aerobic oxidations of cycloheptatrienes to afford benzaldehyde derivatives using CuCl and nitrosoarenes as co-catalysts (10-30 mol %). Our density functional theory calculations support a novel nitroso-activated rearrangement, tropylium → benzylidene. With the same nitrosoarenes, we developed their gold-catalyzed [2 + 2 + 1]-annulations between nitrosobenzene and two enol ethers to yield 5-alkoxyisoxazolidines using 1,4-cyclohexadienes as hydrogen donors.
- Cheng, Mu-Jeng,Kardile, Rahul Dadabhau,Kuo, Tung-Chun,Liu, Rai-Shung,More, Sayaji Arjun
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supporting information
p. 5506 - 5511
(2021/07/31)
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- Palladium-catalyzed synthesis of fluorenes by intramolecular c(sp 2)-h activation at room temperature
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The synthesis of fluorenes by intramolecular Pd-catalyzed C(sp 2)-H activation of 2-arylbenzyl chlorides was conducted at room temperature by using commercially available triphenylphosphine and pivalic acid as ligands. The desired reactions proceeded efficiently at room temperature, and various substrates were converted into the corresponding fluorene derivatives in excellent yields.
- Fujihara, Tetsuaki,Tanji, Yutaka,Tsuji, Yasushi
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supporting information
p. 805 - 808
(2020/05/19)
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- Chromium-Catalyzed, Regioselective Cross-Coupling of C-O Bonds by Using Organic Bromides as Reactants
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We report a chromium-catalyzed cross-coupling of C-O bonds with widely accessible organic bromides as reactants for the preparation of ortho -arylated or -alkylated aromatic aldehydes at room temperature. The use of metallic magnesium is essential for the reaction to occur, giving it an advantage over previous reactions involving Grignard reagents that have to be prepared separately from organic halides before the coupling.
- Tang, Jinghua,Luo, Meiming,Zeng, Xiaoming
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supporting information
p. 2577 - 2580
(2017/09/28)
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- Low-Valent, High-Spin Chromium-Catalyzed Cleavage of Aromatic Carbon-Nitrogen Bonds at Room Temperature: A Combined Experimental and Theoretical Study
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The cleavage of aromatic carbon-nitrogen bonds catalyzed by transition metals is of high synthetic interest because such bonds are common in organic chemistry. However, few metal catalysts can be used to selectively break C(aryl)-N bonds in electronically neutral molecules. We report here the first low-valent, high-spin chromium-catalyzed cleavage of C(aryl)-N bonds in electronically neutral aniline derivatives at room temperature. By using simple and inexpensive chromium(II) chloride as precatalyst, accompanied by an imino auxiliary, the selective arylative and alkylative C-C coupling of C(aryl)-N bonds can be achieved. Crossover experiments indicate that a low-valent chromium species, formed in situ by reduction of CrCl2 with Grignard reagent, is responsible for the catalytic cleavage of C(aryl)-N bonds. DFT calculations show that facile insertion of the C(aryl)-N bond by chromium(0) can take place in a high-spin quintet (S = 2) ground state, whereas the lower-spin singlet (S = 0) and triplet (S = 1) states are inaccessible in energy. It was found that both donation of the sole paired d electrons in the d6 shell of high-spin chromium(0) to the antibonding orbital of the C(aryl)-N bond and the nitrogen ligating interaction to the metal center with its lone pair play important roles in the cleavage of the C(aryl)-N bond by the zerovalent chromium species.
- Cong, Xuefeng,Fan, Fei,Ma, Pengchen,Luo, Meiming,Chen, Hui,Zeng, Xiaoming
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p. 15182 - 15190
(2017/10/31)
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- An active catalytic system for Suzuki-Miyaura cross-coupling reactions using low levels of palladium loading
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An easily available Pd(OAc)2/(2-(anthracen-9-yl)-1H-inden-3-yl) dicyclohexylphosphine/toluene/iPrOH/water catalytic system was developed, which shows high catalytic activity in the Suzuki-Miyaura cross-coupling reactions of a diverse array of aryl and heteroaryl chlorides with Pd loadings down to 0.01 mol%.
- Yan, Meng-Qi,Yuan, Jia,Lan, Fang,Zeng, Si-Hao,Gao, Meng-Yue,Liu, Sheng-Hua,Chen, Jian,Yu, Guang-Ao
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supporting information
p. 3924 - 3929
(2017/07/10)
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- Gold-Catalyzed Oxidation Terminal Alkyne: An Approach to Synthesize Substituted Dihydronaphthalen-2(1H)-ones and Phenanthrenols
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A facile gold-catalyzed oxidation terminal alkynes to synthesize substituted dihydronaphthalen-2(1H)-ones 3 and phenanthrenols 5 was realized. Various useful structures and drug precursors were generated in up to 99% yield under mild condition and low catalyst loading.
- Ling, Hui-Bo,Chen, Zi-Sheng,Yang, Fang,Xu, Bin,Gao, Jin-Ming,Ji, Kegong
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p. 7070 - 7076
(2017/07/15)
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- Silver-Catalyzed Tandem C=C Bond Hydroazidation/Radical Addition/Cyclization of Biphenyl Acetylene: One-Pot Synthesis of 6-Methyl Sulfonylated Phenanthridines
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A silver-catalyzed tandem carbon-carbon triple bond hydroazidation, radical addition, and cyclization of biphenyl acetylene is described under mild conditions, leading to the formation of 6-methyl sulfonylated phenanthridines in good yields. In this novel cascade reaction, most of the atoms are incorporated into the product without cleavage of the C=C bond. Mechanistic studies suggest the reaction should proceed through an iminyl radical reactive intermediate.
- Tang, Jiawei,Sivaguru, Paramasivam,Ning, Yongquan,Zanoni, Giuseppe,Bi, Xihe
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supporting information
p. 4026 - 4029
(2017/08/14)
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- (Biphenyl-2-alkyne) derivatives as common precursors for the synthesis of 9-iodo-10-organochalcogen-phenanthrenes and 9-organochalcogen-phenanthrenes
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In this paper, we report our results on the cyclization of (biphenyl-2-alkyne) derivatives to give two different types of phenanthrene derivatives, 9-iodo-10-organochalcogen-phenanthrenes and 9-organochalcogen-phenanthrenes. The strategy for the synthesis was based on the use of electrophilic cyclization for the preparation of 9-iodo-10-organochalcogen-phenanthrenes and iron(iii) chloride/diorganyl diselenide-mediated intramolecular cyclization to prepare 9-organochalcogen-phenanthrenes. The effects of solvent, temperature, reaction time and stoichiometry on the efficiency of cyclization reactions were investigated. The standard reaction conditions were compatible with many functional groups in the substrates, such as methyl, chlorine, fluorine and methoxyl. This protocol was efficient for diorganyl diselenides and disulfides but ineffective for diorganyl ditellurides. The resulting phenanthrenes were further functionalized through Sonogashira reactions followed by the electrophilic cyclization reaction to give the selenophene-fused aromatic compounds.
- Grimaldi, Tamiris B.,Lutz, Guilherme,Back, Davi F.,Zeni, Gilson
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p. 10415 - 10426
(2016/11/18)
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- 2-Aryl-indenylphosphine ligands: Design, synthesis and application in Pd-catalyzed Suzuki-Miyaura coupling reactions
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A focused library of phosphine ligands was constructed for structural optimization. The catalyst can be used to perform the Suzuki-Miyaura cross-coupling reaction of aryl and heteroaryl chlorides.
- Lian, Ze-Yu,Yuan, Jia,Yan, Meng-Qi,Liu, Yan,Luo, Xue,Wu, Qing-Guo,Liu, Sheng-Hua,Chen, Jian,Zhu, Xiao-Lei,Yu, Guang-Ao
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supporting information
p. 10090 - 10094
(2016/11/06)
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- Regio- and Chemoselective Kumada-Tamao-Corriu Reaction of Aryl Alkyl Ethers Catalyzed by Chromium under Mild Conditions
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Acting as an environmentally benign synthetic tool, the cross-coupling reactions with aryl ethers via C-O bond activation have attracted broad interest. However, the functionalizations of C-O bonds are mainly limited to nickel catalysis, and selectivity has long been a prominent challenge when several C-O bonds are present in the one molecule. We report here the first chromium-catalyzed selective cross-coupling reactions of aryl ethers with Grignard reagents by the cleavage of C-O(alkyl) bonds. Diverse transformations were achieved using simple, inexpensive chromium(II) precatalyst combining imino auxiliary at room temperature. It offers a new avenue for buildup functionalized aromatic aldehydes with high efficiency and selectivity.
- Cong, Xuefeng,Tang, Huarong,Zeng, Xiaoming
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supporting information
p. 14367 - 14372
(2015/12/01)
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- Pinpoint-fluorinated phenanthrene synthesis based on C-F bond activation of difluoroalkenes Dedicated to Prof. Véronique Gouverneur on the occasion of her receipt of the 2014 ACS Award for Creative Work in Fluorine Chemistry.
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Treatment with a cationic palladium(II) catalyst promoted the Friedel-Crafts-type cyclization of 1,1-difluoro-1-alkenes bearing a biphenyl skeleton to afford regioselectively fluorinated (pinpoint-fluorinated) phenanthrenes via C-F bond activation. The obtained pinpoint-fluorinated phenanthrenes were observed to be organized by π-π and C-H?F interactions to exhibit columnar and layer structures in the solid state.
- Fuchibe, Kohei,Morikawa, Toshiyuki,Ueda, Ryu,Okauchi, Tatsuo,Ichikawa, Junji
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supporting information
p. 106 - 115
(2015/11/10)
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- Formation of a carbonyl group ortho to a biaryl structure or a 6H-dibenzopyran by a palladium/norbornene-catalyzed ordered reaction sequence
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Abstract Developments are reported in the catalytic synthesis of biaryls containing an ortho-carbaldehyde or 6H-dibenzopyrans in the presence of palladium/norbornene as catalyst. The reaction of o-substituted aryl iodides and o-bromobenzyl alcohols proceeds by unsymmetrical aryl-aryl coupling to form a seven-membered oxapalladacycle intermediate, which may undergo an intramolecular redox process to form carbonyl groups or a C-O coupling to six-membered cyclic ethers. The predominant formation of dibenzopyrans as well as of biaryl structures containing the oxidized CHO group in one ring and the reduced CH2OH in the other is described along with some mechanistic insights.
- Della Ca, Nicola,Fontana, Marco,Xu, Di,Cremaschi, Mirko,Lucentini, Riccardo,Zhou, Zhi-Ming,Catellani, Marta,Motti, Elena
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p. 6389 - 6401
(2015/08/18)
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- Copper catalyzed room temperature lactonization of aromatic C-H bond: A novel and efficient approach for the synthesis of dibenzopyranones
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We have developed a novel and efficient methodology for the intramolecular aryl C-H oxidative lactonization of 2-arylbenzaldehyde using a low-cost CuCl catalyst and TBHP as the oxidant at room temperature. We applied the methodology to the synthesis of a series of dibenzopyranones.
- Singha, Raju,Dhara, Shubhendu,Ghosh, Munmun,Ray, Jayanta K.
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p. 8801 - 8805
(2015/03/03)
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- Catalytic oxidative cyclization of 2′-arylbenzaldehyde oxime ethers under photoinduced electron transfer conditions
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A series of 2′-arylbenzaldehyde oxime ethers were synthesized and shown to generate the corresponding phenanthridines upon irradiation in the presence of 9,10-dicyanoanthracene in acetonitrile. Mechanistic studies suggest that the oxidative cyclization reaction sequence is initiated by an electron transfer step followed by nucleophilic attack of the aryl ring onto the nitrogen of the oxime ether. A concave downward Hammett plot is presumably the result of a change in charge distribution in the radical cation species with strongly electron-donating substituents that yields a less electrophilic nitrogen atom and a decreased amount of cyclized product. The reaction is selective (no nitrile byproduct is formed unlike other photochemical reactions involving aldoxime ethers) as well as regiospecific when using 2′-aryl groups with metasubstituents, making this reaction a useful alternative for preparing substituted phenanthridines.
- Hofstra, Julie L.,Grassbaugh, Brittany R.,Tran, Quan M.,Armada, Nicholas R.,De Lijser, H. J. Peter
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p. 256 - 265
(2016/09/09)
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- Atom-economic threefold cross-couplings of triarylbismuth reagents with 2-halobenzaldehydes and pot-economic in situ Wittig functionalizations with phosphonium salts
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In this paper we report an efficient pot-economic methodology for the synthesis of ortho-olefinated biaryls. This has been achieved through an atom-economic threefold cross-coupling of triarylbismuth reagents with 2-halobenzaldehydes followed by pot-economic in situ Wittig olefination. The overall process is a pot-economic straightforward synthesis of ortho-olefinated biaryls from 2-halobenzaldehydes, triarylbismuth reagents and phosphonium salts. This pot-economic approach was applied to the formal synthesis of medicinally important Eupomatilone-6.
- Rao, Maddali L. N.,Dhanorkar, Ritesh J.
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p. 63792 - 63806
(2015/02/19)
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- Bismuth-catalyzed synthesis of polycyclic aromatic hydrocarbons (PAHs) with a phenanthrene backbone via cyclization and aromatization of 2-(2-arylphenyl)vinyl ethers
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The reaction of 2-(2-arylphenyl)vinyl ethers in the presence of a catalytic amount of bismuth(III) triflate gave substituted phenanthrenes in excellent yields under mild reaction conditions. The reaction was also applied to the construction of other polycyclic aromatic hydrocarbons (PAHs), such as chrysene, helicene, and pyrene having a phenanthrene backbone, via regioselective cyclization. This method has the advantages of easy availability of the cyclization precursors, operational simplicity, and high reaction efficiency.
- Murai, Masahito,Hosokawa, Naoki,Roy, David,Takai, Kazuhiko
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p. 4134 - 4137
(2014/09/30)
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- Cross dehydrogenative coupling via base-promoted homolytic aromatic substitution (BHAS): Synthesis of fluorenones and xanthones
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Cross dehydrogenative coupling reactions occurring via base-promoted homolytic aromatic substitutions (BHASs) are reported. Fluorenones and xanthones are readily prepared via CDC starting with readily available ortho-formyl biphenyls and ortho-formyl biphenylethers, respectively. The commercially available and cheap tBuOOH is used as an oxidant. Initiation of the radical chain reaction is best achieved with small amounts of FeCp2 (0.1 or 1 mol %).
- Wertz, Sebastian,Leifert, Dirk,Studer, Armido
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supporting information
p. 928 - 931
(2013/03/28)
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- Focused pseudostatic hydrazone libraries screened by mass spectrometry binding assay: Optimizing affinities toward γ-aminobutyric acid transporter 1
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Mass spectrometric (MS) binding assays, a powerful tool to determine affinities of single drug candidates toward chosen targets, were recently demonstrated to be suitable for the screening of compound libraries generated with reactions of dynamic combinatorial chemistry when rendering libraries pseudostatic. Screening of small hydrazone libraries targeting γ-aminobutyric acid transporter 1 (GAT1), the most abundant γ-aminobutyric acid (GABA) transporter in the central nervous system, revealed two nipecotic acid derived binders with submicromolar affinities. Starting from the biphenyl carrying hit as lead structure, the objective of the present study was to discover novel high affinity GAT1 binders by screening of biphenyl focused pseudostatic hydrazone libraries formed from hydrazine 10 and 36 biphenylcarbaldehydes 11c-al. Hydrazone 12z that carried a 2′,4′-dichlorobiphenyl residue was found to be the most potent binder with low nanomolar affinity (pKi = 8.094 ± 0.098). When stable carba analogues of representative hydrazones were synthesized and evaluated, the best binder 13z was again displaying the 2′,4′- dichlorobiphenyl moiety (pKi = 6.930 ± 0.021).
- Sindelar, Miriam,Lutz, Toni A.,Petrera, Marilena,Wanner, Klaus T.
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supporting information
p. 1323 - 1340
(2013/04/10)
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- A sequential Pd/norbornene-catalyzed process generates o- biaryl carbaldehydes or ketones via a redox reaction or 6 h -dibenzopyrans by C-O ring closure
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o-Biaryl carbaldeydes and ketones are obtained through the one-pot reaction of o-aryl iodides with o-bromobenzyl alcohols under the catalytic action of Pd and norbornene, in the presence of a base. The same reaction can also give dibenzopyrans by Pd and norbornene catalysis with a different termination, leading to C-O ring closure. In both cases the process first leads to a five-membered palladacycle, which controls C-C coupling, then to a seven-membered oxapalladacycle, which gives aldehydes and ketones or dibenzopyrans.
- Motti, Elena,Ca, Nicola Della,Xu, Di,Piersimoni, Anna,Bedogni, Elena,Zhou, Zhi-Ming,Catellani, Marta
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supporting information
p. 5792 - 5795
(2013/01/15)
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- Facile Cu(OTf)2-catalyzed preparation of 9-tosylaminofluorene derivatives from o-arylated N-tosylbenzaldimines
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The 9-tosylaminofluorene derivatives were synthesized conveniently by Cu(OTf)2-catalyzed aza-Friedel-Crafts reaction of o-arylated N-tosylbenzaldimines in high yields. This is an efficient, atom-economic, and green method.
- Yu, Xufen,Lu, Xiyan
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scheme or table
p. 2076 - 2079
(2011/05/09)
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- Triaromatic compounds and pharmaceutical/cosmetic compositions comprised thereof
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Novel pharmaceutically/cosmetically-active triaromatic compounds have the structural formula (I): and are useful for the treatment of a wide variety of disease states, whether human or veterinary, for example dermatological, rheumatic, respiratory, cardiovascular, bone and ophthalmological disorders, as well as for the treatment of mammalian skin and hair conditions/disorders.
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