- Pd-Catalysed Suzuki-Miyaura cross-coupling of aryl chlorides at low catalyst loadings in water for the synthesis of industrially important fungicides
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The Suzuki-Miyaura coupling reaction of electron-poor aryl chlorides in the synthesis of crop protection-relevant active ingredients in water is disclosed. Optimisation of the reaction conditions allowed running the reaction with 50 ppm of Pd-catalyst loading without an additional organic solvent in the cross-coupling reaction step in short reaction times. The system was optimised for the initial cross-coupling step of the large scale produced fungicides Boscalid, Fluxapyroxad and Bixafen up to 97% yield. It is also shown that the Suzuki-Miyaura reaction can be easily scaled up to 50 g using a simple product separation and purification using environmentally benign solvents in the work-up. To show the usability of this method, it was additionally applied in the three-step synthesis of the desired active ingredients.
- Goetz, Roland,Hashmi, A. Stephen K.,Orecchia, Patrizio,Petkova, Desislava Slavcheva,Rominger, Frank,Schaub, Thomas
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supporting information
p. 8169 - 8180
(2021/11/01)
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- NaI/PPh3-Mediated Photochemical Reduction and Amination of Nitroarenes
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A mild transition-metal- and photosensitizer-free photoredox system based on the combination of NaI and PPh3 was found to enable highly selective reduction of nitroarenes. This protocol tolerates a broad range of reducible functional groups such as halogen (Cl, Br, and even I), aldehyde, ketone, carboxyl, and cyano. Moreover, the photoredox catalysis with NaI and stoichiometric PPh3 provides also an alternative entry to Cadogan-type reductive amination when o-nitrobiarenes were used.
- Qu, Zhonghua,Chen, Xing,Zhong, Shuai,Deng, Guo-Jun,Huang, Huawen
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supporting information
p. 5349 - 5353
(2021/07/21)
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- Visible-light-driven Cadogan reaction
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Visible-light-driven photochemical Cadogan-type cyclization has been discovered. The organic D-A type photosensitizer 4CzIPN found to be an efficient mediator to transfer energy from photons to the transient intermediate that breaks the barriers of deoxygenation in Cadogan reaction and enables a mild metal-free access to carbazoles and related heterocycles. DFT calculation results indicate mildly endergonic formation of the intermediate complex of nitrobiarenes and PPh3, which corresponds with experimental findings regarding reaction temperature. The robust synthetic capacity of the photoredox Cadogan reaction systems has been demonstrated by the viable productivity of a broad range of carbazoles and related N-heterocycles with good tolerance of various functionalities.
- Qu, Zhonghua,Wang, Pu,Chen, Xing,Deng, Guo-Jun,Huang, Huawen
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supporting information
p. 2582 - 2586
(2021/03/09)
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- Transition-metal-free synthesis of phenanthridinones from biaryl-2-oxamic acid under radical conditions
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Na2S2O8-promoted decarboxylative cyclization of biaryl-2-oxamic acid for phenanthridinones has been developed. This work illustrates the first example of intramolecular decarboxylative amidation of unactivated arene under transition-metal-free conditions. Additionally, this approach provides an efficient and economical method to access biologically interesting phenanthridinones, an important structure motif in many natural products. (Chemical Equation Presented).
- Yuan, Ming,Chen, Li,Wang, Junwei,Chen, Shenjie,Wang, Kongchao,Xue, Yongbo,Yao, Guangmin,Luo, Zengwei,Zhang, Yonghui
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supporting information
p. 346 - 349
(2015/02/19)
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- N-Sulfonyl-aminobiaryls as Antitubulin Agents and Inhibitors of Signal Transducers and Activators of Transcription 3 (STAT3) Signaling
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A series of N-sulfonyl-aminobiaryl derivatives have been examined as novel antitubulin agents. Compound 21 [N-(4′-cyano-3′-fluoro-biphenyl-2-yl)-4-methoxy-benzenesulfonamide] exhibits remarkable antiproliferative activity against four cancer cell lines (pancreatic AsPC-1, lung A549, liver Hep3B, and prostate PC-3) with a mean GI50 value of 57.5 nM. Additional assays reveal that 21 inhibits not only tubulin polymerization but also the phosphorylation of STAT3 inhibition with an IC50 value of 0.2 μM. Four additional compounds (8, 10, 19, and 35) are also able to inhibit this phosphorylation. This study describes novel N-sulfonyl-aminobiaryl (biaryl-benzenesulfonamides) as potent anticancer agents targeting both STAT3 and tubulin. (Chemical Equation Presented).
- Lai, Mei-Jung,Lee, Hsueh-Yun,Chuang, Hsun-Yueh,Chang, Li-Hsun,Tsai, An-Chi,Chen, Mei-Chuan,Huang, Han-Lin,Wu, Yi-Wen,Teng, Che-Ming,Pan, Shiow-Lin,Liu, Yi-Min,Mehndiratta, Samir,Liou, Jing-Ping
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p. 6549 - 6558
(2015/09/07)
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- Rapid synthesis of fused N-heterocycles by transition-metal-free electrophilic amination of arene C-H bonds
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We disclose an efficient and operationally simple protocol for the preparation of fused N-heterocycles starting from readily available 2-nitrobiaryls and PhMgBr under mild conditions. More than two dozen N-heterocycles, including two bioactive natural products, have been synthesized using this method. A stepwise electrophilic aromatic cyclization mechanism was proposed by DFT calculations. Controlled fusion: A transition-metal-free, low-temperature, and regioselective intramolecular amination of aromatic C(sp2)-H bonds provides fused N-heterocycles. This reaction is operationally simple and scalable (1-10 mmol) and the scope of substrates is wide (see scheme). Density functional calculations indicate that a stepwise electrophilic aromatic cyclization mechanism may be operative.
- Gao, Hongyin,Xu, Qing-Long,Yousufuddin, Muhammed,Ess, Daniel H.,Kuerti, Laszlo
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supporting information
p. 2701 - 2705
(2014/03/21)
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- Palladium-catalyzed direct arylation of nitro-substituted aromatics with aryl halides
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(Chemical Equation Presented) Direct arylation reactions of nitrobenzenes and aryl halides occur in good yield and high ortho regioselectivity. These reactions can be performed on gram scale with as few as 3 equiv of the nitro arene relative to the aryl halide. The synthetic utility of this method is demonstrated via rapid synthesis of a Boscalid intermediate.
- Caron, Laurence,Campeau, Louis-Charles,Fagnou, Keith
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supporting information; experimental part
p. 4533 - 4536
(2009/05/07)
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- Method For Decarboxylating C-C Cross-Linking Of Carboxylic Acids With Carbon Electrophiles
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The invention relates to a method for decarboxylating C—C bond formation by reacting carboxylic salts with carbon electrophiles in the presence of transition metal compounds as catalysts. The method represents a decarboxylating C—C bond formation of carboxylic acid salts with carbon electrophiles, wherein the catalyst contains two transition metals and/or transition metal compounds, from which one is present, preferably, in the oxidation step, which are different from each other by one unit, and catalyzes a radical decarboxylation which is absorbed during the second oxidation steps, which are different from each other by two units and catalyzes the two electron processes of a C—C bond formation reaction.
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Page/Page column 8-9
(2008/12/07)
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- Suzuki-Miyaura cross-coupling of 2-nitroarenediazonium tetrafluoroborates: Synthesis of unsymmetrical 2-nitrobiphenyls and highly functionalized carbazoles
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The Suzuki-Miyaura cross-coupling of 2-nitrodiazonium tetrafluoroborate salts with substituted boronic acids is an effective and efficient means of preparing highly functionalized 2-nitrobiphenyls in modest to excellent yield under extremely mild reaction conditions. Cross-coupling of 2-nitrodiazonium tetrafluoroborate salts with ortho-methoxy- and benzyloxyphenylboronic acids was also demonstrated leading to the ortho-ortho-2-nitrobiphenyls. Reductive cyclization of the 2-nitrobiphenyl products allows for the overall three-step synthesis of uniquely substituted carbazoles from readily available 2-nitroanilines. The methodology was further highlighted by the short total synthesis of the carbazole alkaloids clausine V, N, C, and glycoborine.
- Kuethe, Jeffrey T.,Childers, Karla G.
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supporting information; experimental part
p. 1577 - 1586
(2009/07/01)
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- Palladium/copper-catalyzed decarboxylative cross-coupling of aryl chlorides with potassium carboxylates
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(Chemical Equation Presented) Even non-activated aryl chlorides undergo decarboxylative cross-coupling reactions in the presence of a catalyst system generated in situ from CuI, 1,10-phenanthroline, PdI2, and di(tert-butyl)biphenylphosphane. The new catalyst is useful for both the synthesis of biaryl compounds from aromatic carboxylates and the synthesis of aryl ketones from salts of α-ketocarboxylic acids (see scheme; FG=functional group; R=aryl, alkyl).
- Goossen, Lukas J.,Zimmermann, Bettina,Knauber, Thomas
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experimental part
p. 7103 - 7106
(2009/04/12)
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- Biaryl synthesis via Pd-catalyzed decarboxylative coupling of aromatic carboxylates with aryl halides
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A new strategy for the regiospecific construction of unsymmetrical biaryls is presented, in which easily available salts of carboxylic acids are decarboxylated in situ to give arylmetal species that serve as the nucleophilic component in a catalytic cross-coupling reaction with aryl halides. The catalyst system consists of a copper phenanthroline complex that mediates the extrusion of CO2 from aromatic carboxylates to generate arylcopper species, and a palladium complex that catalyzes the cross-coupling of these intermediates with aryl halides. This bimetallic system allows the direct coupling of various aryl, heteroaryl, or vinyl carboxylic acids with aryl or heteroaryl iodides, bromides, or chlorides at 160°C in the presence of a mild base such as potassium carbonate. The present scope and potential economic impact of the reaction are demonstrated by the synthesis of 42 biaryls, some of which are of substantial industrial relevance. Remaining challenges and future perspectives of the new transformation are discussed.
- Goossen, Lukas J.,Rodriguez, Nuria,Melzer, Bettina,Linder, Christophe,Deng, Guojun,Levy, Laura M.
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p. 4824 - 4833
(2008/01/27)
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- Microwave-enhanced cadogan cyclization: An easy access to the 2-substituted carbazoles and other fused heterocyclic systems
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A microwave-enhanced Suzuki-Miyaura cross-coupling reaction in combination with a microwave-assisted Cadogan reductive cyclization is presented as an easy access to a variety of 2-substituted carbazoles and other fused heterocyclic systems. Microwave irradiation was found very useful in minimizing the proto-deboronation issues in the cross-coupling reaction, and enhances the rate of reductive cyclization in a dramatic manner.
- Appukkuttan, Prasad,Van Der Eycken, Erik,Dehaen, Wim
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p. 127 - 133
(2007/10/03)
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- SYNTHESIS OF 4-ALKOXY-4'-CYANOBIPHENYLS
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A preparative method was developed for the synthesis of liquid crystals of the 4-alkoxy-4'-cyanobiphenyl group.It involves the nitration of 4-cyanobiphenyl to 4-nitro-4'-cyanobiphenyl, reduction of the latter, diazotization of the obtained 4-amino-4'-cyanobiphenyl, and alkylation of the 4-hydroxy-4'-cyanobiphenyl formed during decomposition of the diazonium salt.
- Ruolene, Yu. I.,Adomenas, P. V.,Adomenene, O. K.,Denis, G. I.
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p. 1192 - 1195
(2007/10/02)
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