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Journal articles on the topic 'Coupling reactions via aryne intermediates'

Author: Grafiati

Published: 19 April 2025

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1

Kobayashi, Tsuneyuki, Takamitsu Hosoya, and Suguru Yoshida. "Facile Synthetic Methods for Diverse N-Arylphenylalanine Derivatives via Transformations of Aryne Intermediates and Cross-Coupling Reactions." Bulletin of the Chemical Society of Japan 94, no. 7 (July 15, 2021): 1823–32. http://dx.doi.org/10.1246/bcsj.20210149.

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2

Surina, Anastasia, Karolína Salvadori, Matěj Poupě, Jan Čejka, Ludmila Šimková, and Pavel Lhoták. "Upper Rim-Bridged Calix[4]arenes via Cyclization of meta Alkynyl Intermediates with Diphenyl Diselenide." Molecules 29, no. 6 (March 11, 2024): 1237. http://dx.doi.org/10.3390/molecules29061237.

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A Sonogashira coupling of meta-iodocalix[4]arene with various terminal acetylenes confirmed that the meta position of calixarene is well addressable, and that both thermal and microwave protocols led to good yields of alkynylcalixarenes. Alkynes thus obtained were subjected to the ferric chloride and diphenyl diselenide-promoted electrophilic closure. It turns out that the calix[4]arenes give completely different bridging products than those described for the non-macrocyclic starting compounds. This can be demonstrated not only by the isolation of products with a six-membered ring (6-exo-dig), but mainly by the smooth formation of the 5-endo-dig cyclization, which has never been observed in the aliphatic series. An attempt at electrocyclization led to a high yield of the 1,2-diketone (oxidation of the starting alkyne), again in contrast to the reaction described for the acyclic derivatives. The structures of the unexpected products were unequivocally established by X-ray analysis and clearly demonstrate how the preorganized macrocyclic skeleton favors a completely different regioselectivity of cyclization reactions compared to common aliphatic compounds.

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3

Chandrasoma, Nalin, Sivadarshini Pathmanathan, and Keith R. Buszek. "A practical, multi-gram synthesis of (±)-herbindole A, (±)-herbindole B, and (±)-herbindole C from a common intermediate via 6,7-indole aryne cycloaddition and Pd(0)-catalyzed cross-coupling reactions." Tetrahedron Letters 56, no. 23 (June 2015): 3507–10. http://dx.doi.org/10.1016/j.tetlet.2015.02.064.

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4

Liu, Baohua, Chunyan Mao, Qiong Hu, Liangliang Yao, and Yimin Hu. "Direct methylation and carbonylation of in situ generated arynes via HDDA-Wittig coupling." Organic Chemistry Frontiers 6, no. 15 (2019): 2788–91. http://dx.doi.org/10.1039/c9qo00621d.

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A high-efficiency HDDA-Wittig coupling strategy for synthesis of fully functionalized benzenes is reported. Direct methylation and carbonylation of aryne intermediates reacted with phosphorus ylides to form the carbonylated 2,3-dihydro-1H-indenes.

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5

Dong, Yuyang, Michael I. Lipschutz, and T. Don Tilley. "Regioselective, Transition Metal-Free C–O Coupling Reactions Involving Aryne Intermediates." Organic Letters 18, no. 7 (March 24, 2016): 1530–33. http://dx.doi.org/10.1021/acs.orglett.6b00183.

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6

Nhari, Laila M., Elham N. Bifari, Aisha R. Al-Marhabi, Huda A. Al-Ghamdi, Sameera N. Al-Ghamdi, Fatimah A. M. Al-Zahrani, Khalid O. Al-Footy, and Reda M. El-Shishtawy. "Synthesis of Novel Key Chromophoric Intermediates via C-C Coupling Reactions." Catalysts 12, no. 10 (October 21, 2022): 1292. http://dx.doi.org/10.3390/catal12101292.

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The fundamentals of Pd-catalyzed Csp2−Csp2 Miyaura borylation, Suzuki cross-coupling, and Stille cross-coupling reactions for a variety of borylated precursors based on phenothiazine (PTZ), phenoxazine (POZ), carbazole (Cz), and quinoxaline (QX) units have been explored. Three palladium-based catalysts were chosen for this study: Pd(PPh3)4, Pd(PPh3)2Cl2, and Pd(dppf)Cl2, applying different reaction conditions. Around 16 desired chromophores were successfully designed and synthesized using C-C cross-coupling reactions in moderate to excellent yields, including PTZ, POZ, and Cz units coupled with QX, indolinium iodide, thienyl, phenyl, or triphenylamine moieties. Additionally, PTZ, POZ, and Cz have been employed in synthesizing various pinacol boronate ester derivatives in good to moderate yields. Interestingly, Pd(dppf)Cl2 was found to be the best catalyst for borylation, and C-C cross-coupling reactions occurred in as little as 30 min, with an excellent yield exceeding 98%. Pd(PPh3)4 and Pd(PPh3)2Cl2 catalyzed the reaction to obtain the desired products in moderate to good yields after a long time (20–24 h). On the other hand, the Suzuki-Miyaura cross-coupling between N-(2-methyl)hexyl carbazole pinacol boronate ester derivative 10c and three halogenated quinoxaline derivatives—4-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)benzaldehyde (27), 4-(5-(3-(5-bromothiophen-2-yl)quinoxalin-2-yl)thiophen-2-yl)benzaldehyde (30), and 4-(3-chloroquinoxalin-2-yl)benzaldehyde (25) catalyzed by Pd(PPh3)4—afforded three carbazole-quinoxaline chromophores (28, 30, and 31, respectively) in 2–3 h, with good to excellent yields reaching 86%. The electron-deficient QX couplers proved to be coupled efficiently using the Stille coupling reaction, which involves the coupling between electron-rich orgaostannane and electron-deficient halide. The synthesized precursors and desired chromophores were characterized by FTIR, 1H-NMR, 13C-NMR, and HRMS.

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7

Burt, Liam K., Richard L. Cordiner, Anthony F. Hill, Richard A. Manzano, and Jörg Wagler. "The significance of phosphoniocarbynes in halocarbyne cross-coupling reactions." Chemical Communications 56, no. 42 (2020): 5673–76. http://dx.doi.org/10.1039/d0cc02070b.

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Competent intermediates as well as productive and non-productive tangents have been identified in the catalytic cycle for palladium(0)–copper(i) mediated synthesis of propargylidynes via cross coupling reactions of bromocarbyne complexes with alkynes.

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8

Tang, Jianting, Leiyang Lv, Xi-Jie Dai, Chen-Chen Li, Lu Li, and Chao-Jun Li. "Nickel-catalyzed cross-coupling of aldehydes with aryl halides via hydrazone intermediates." Chemical Communications 54, no. 14 (2018): 1750–53. http://dx.doi.org/10.1039/c7cc09290c.

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A novel nickel-catalyzed cross-coupling reaction between aldehydes and aryl halides via hydrazone intermediates has been developed. It merges the Wolff–Kishner reduction and classical cross-coupling reactions, thus opening up new routes in designing chemical synthesis.

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9

Friese, Florian W., and Armido Studer. "New avenues for C–B bond formation via radical intermediates." Chemical Science 10, no. 37 (2019): 8503–18. http://dx.doi.org/10.1039/c9sc03765a.

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Efficient radical routes to important alkyl and aryl boronic esters have been developed over the past few years. Such reactions are complementary to existing transition-metal catalysed cross coupling processes.

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10

Zhao, Yin-Na, Yong-Chun Luo, Zhu-Yin Wang, and Peng-Fei Xu. "A new approach to access difluoroalkylated diarylmethanes via visible-light photocatalytic cross-coupling reactions." Chemical Communications 54, no. 32 (2018): 3993–96. http://dx.doi.org/10.1039/c8cc01486h.

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11

Hilton, Michael C., Xuan Zhang, Benjamin T. Boyle, Juan V. Alegre-Requena, Robert S. Paton, and Andrew McNally. "Heterobiaryl synthesis by contractive C–C coupling via P(V) intermediates." Science 362, no. 6416 (November 15, 2018): 799–804. http://dx.doi.org/10.1126/science.aas8961.

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Heterobiaryls composed of pyridine and diazine rings are key components of pharmaceuticals and are often central to pharmacological function. We present an alternative approach to metal-catalyzed cross-coupling to make heterobiaryls using contractive phosphorus C–C couplings, also termed phosphorus ligand coupling reactions. The process starts by regioselective phosphorus substitution of the C–H bonds para to nitrogen in two successive heterocycles; ligand coupling is then triggered via acidic alcohol solutions to form the heterobiaryl bond. Mechanistic studies imply that ligand coupling is an asynchronous process involving migration of one heterocycle to the ipso position of the other around a central pentacoordinate P(V) atom. The strategy can be applied to complex drug-like molecules containing multiple reactive sites and polar functional groups, and also enables convergent coupling of drug fragments and late-stage heteroarylation of pharmaceuticals.

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12

Zhu, Chenghao, and Junliang Zhang. "Nickel-catalyzed alkyl–alkyl cross-coupling reactions of non-activated secondary alkyl bromides with aldehydes as alkyl carbanion equivalents." Chemical Communications 55, no. 19 (2019): 2793–96. http://dx.doi.org/10.1039/c9cc00307j.

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13

An, Ran, Mengbi Guo, Yingbo Zang, Hang Xu, Zhuang Hou, and Chun Guo. "Recent Advances in Synthesis of Benzazoles via Imines." Current Organic Chemistry 24, no. 17 (November 12, 2020): 1897–942. http://dx.doi.org/10.2174/1385272824999200818180845.

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Imines, versatile intermediates for organic synthesis, can be exploited for the preparation of diverse classes of biologically active benzazoles. Because of the special characteristics of the C=N bond, imines can be simultaneously used in the synthesis of 1,3-benzazoles and 1,2-benzazoles. With the development of imine synthesis, a variety of novel cascade reactions for benzazole synthesis have been reported in the last decade. Therefore, there is a strong need to elucidate the recent progress in the formation of various classes of benzazoles, including benzimidazoles, benzoxazoles, benzothiazoles, indazoles, and benzisoxazoles, via imines obtained by condensation reactions or oxidative/ redox coupling reactions

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14

Weske, Sebastian, Richard A. Hardin, Thomas Auth, Richard A. J. O’Hair, Konrad Koszinowski, and Craig A. Ogle. "Argentate(i) and (iii) complexes as intermediates in silver-mediated cross-coupling reactions." Chemical Communications 54, no. 40 (2018): 5086–89. http://dx.doi.org/10.1039/c8cc01707g.

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Silver-mediated cross-coupling reactions proceed via anionic ate complexes, which have been characterized by a combination of NMR spectroscopy, ESI mass spectrometry, and quantum-chemical calculations.

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15

Takaki, Ken, Makoto Hino, Akira Ohno, Kimihiro Komeyama, Hiroto Yoshida, and Hiroshi Fukuoka. "NHC-catalyzed cleavage of vicinal diketones and triketones followed by insertion of enones and ynones." Beilstein Journal of Organic Chemistry 13 (August 30, 2017): 1816–22. http://dx.doi.org/10.3762/bjoc.13.176.

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Thiazolium carbene-catalyzed reactions of 1,2-diketones and 1,2,3-triketones with enones and ynones have been investigated. The diketones gave α,β-double acylation products via unique Breslow intermediates isolable as acid salts, whereas the triketones formed stable adducts with the NHC instead of the coupling products.

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16

Charron, Carlie L., Jade M. Cottam Jones, and Craig A. Hutton. "Are Aminomethyl Thioesters Viable Intermediates in Native Chemical Ligation Type Amide Bond Forming Reactions?" Australian Journal of Chemistry 71, no. 9 (2018): 697. http://dx.doi.org/10.1071/ch18198.

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The condensation of N-mercaptomethyl amines and thioesters is a potential route to amides, via aminomethyl thioester intermediates, in a native chemical ligation type process followed by self-cleavage of the ‘mercaptomethyl’ auxiliary. This paper describes investigations towards the preparation of aminomethyl thioesters, and subsequent conversion into amides, from a three-component coupling of formaldehyde, a thioacid, and an amine. Our studies suggest that while such intermediates may be formed en route to amides, no advantages are offered over the direct reaction of the amine and thioacid precursors.

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17

Du, Yu, Yuhuang Wang, Xin Li, Yaling Shao, Guohui Li, Richard D. Webster, and Yonggui Robin Chi. "N-Heterocyclic Carbene Organocatalytic Reductive β,β-Coupling Reactions of Nitroalkenes via Radical Intermediates." Organic Letters 16, no. 21 (October 24, 2014): 5678–81. http://dx.doi.org/10.1021/ol5027415.

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18

Heggen, Berit, and Walter Thiel. "Theoretical investigation on the mechanism of iron catalyzed cross coupling reactions via ferrate intermediates." Journal of Organometallic Chemistry 804 (February 2016): 42–47. http://dx.doi.org/10.1016/j.jorganchem.2015.12.026.

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19

Hao, Xiaoyu, Yan Li, Hongyan Ji, Tingting Wang, Haolong Fan, Quanzhen Zhang, Huixia Yang, Liwei Liu, Teng Zhang, and Yeliang Wang. "Direct Visualization of Organometallic Intermediates on Cu(111) with Bond-Resolving Non-Contact Atomic Force Microscopy." Surfaces 7, no. 3 (August 1, 2024): 529–36. http://dx.doi.org/10.3390/surfaces7030035.

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In this study, we investigated the surface-confined coupling reactions of 1,8-dibromobiphenylene (BPBr2) on Cu(111) to elucidate the details of the organometallic intermediates via Ullmann reactions. We used scanning tunneling microscopy (STM) to characterize the resulting organometallic intermediates. Moreover, submolecular resolution of the non-contact atomic force microscopy (nc-AFM) qPlus technique enables the bond-resolving within the organometallic dimer product. Our findings reveal the debromination of BPBr2 on Cu(111), leading to the formation of an organometallic dimer intermediate at room temperature. Through nc-AFM measurements, we confirm and visualize the formation of the C-Cu-C bond. These insights enhance our understanding of Ullmann reaction and hold potential implications for the design of novel two-dimensional electronic devices.

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20

Torrado, María, Christian F. Masaguer, and Enrique Raviña. "Synthesis of substituted tetralones as intermediates of CNS agents via palladium-catalyzed cross-coupling reactions." Tetrahedron Letters 48, no. 2 (January 2007): 323–26. http://dx.doi.org/10.1016/j.tetlet.2006.10.154.

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21

Deng, Danfeng, Dayun Huang, Xiangyu Sun, and Biwen Gao. "Recent Advances in the Tandem Difunctionalization of Alkynes: Mechanism-Based Classification." Synthesis 53, no. 19 (April 19, 2021): 3522–34. http://dx.doi.org/10.1055/a-1486-2158.

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AbstractRecent advances on the tandem difunctionalization of alkynes in the last decade (2010–2020) are summarized into five categories based on the type of mechanism: (1) radical addition and coupling for the synthesis of polysubstituted ketones and alkenes, (2) electrophilic addition of alkynes, (3) reactions mediated by haloalkynes or copper acetylides, (4) the preparation of cyclic compounds via radical processes, palladium-catalyzed reactions or conjugate additions, and (5) cyclic compounds as intermediates in ring openings. Herein, radical, electrophilic and nucleophilic reactions are discussed in detail. We hope this review will help to promote future research in this area. 1 Introduction2 Radical Addition and Coupling3 Electrophilic Addition4 Reactions Mediated by Haloalkynes or Copper Acetylides5 Cyclization6 Cyclization and Ring Opening7 Conclusions

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22

Wang, Menglan, Yudong Li, Qing-An Wu, Shuping Luo, and Yuehui Li. "Iron-Promoted Construction of Indoles via Intramolecular Oxidative C–N Coupling of 2-Alkenylanilines Using Persulfate." Synthesis 51, no. 16 (April 30, 2019): 3085–90. http://dx.doi.org/10.1055/s-0037-1611521.

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Indole scaffold synthesis relies primarily on oxidative C–H amination of N-protected alkenylanilines for C–N intramolecular cyclization reactions. Herein, for the first time, without N-protection, various readily prepared 2-alkenylanilines were transformed into the desired indole products in good yields by using K2S2O8 as oxidant in the presence of catalytic amounts of FeF2. The K2S2O8/FeF2 system offers a direct and benign synthetic route to 3-arylindoles and it is applicable to a wide range of substituted indoles including drug intermediates.

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23

Sakamoto, Naonari, Keita Sekizawa, Soichi Shirai, Takamasa Nonaka, Takeo Arai, Shunsuke Sato, and Takeshi Morikawa. "(Digital Presentation) Investigate the Reaction Mechanism in the C3H7OH Electrochemical Reduction Reaction from CO₂ Using Dinuclear Cuprous Molecular Catalyst." ECS Meeting Abstracts MA2024-02, no. 62 (November 22, 2024): 4256. https://doi.org/10.1149/ma2024-02624256mtgabs.

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The urgent global challenge of climate change and the depletion of energy resources have spotlighted the technology of converting carbon dioxide (CO2) into valuable carbon-based products. The CO2 reduction reaction (CO2RR) via metal complex molecules is expected to improve and enhance the electronic/chemical environment of the catalytic active sites through control with freely modulable organic ligands. The selectivity for the formation of formic acid and carbon monoxide from CO2 in organic solvents has been successfully controlled in some molecular catalysts by small structural differences in the ligands. For catalytic reactions in organic solvents, NMR and other common analytical methods can be used to follow structural changes and reaction intermediates during the reaction of unimolecular molecular catalysts. The study of detailed reaction processes has led to ligand design guidelines that contribute to higher reaction rates and improved selectivity. However, analytical methods still need to be developed for heterogeneous molecular catalysts used in water on electrodes. Catalysts capable of producing C2 products, such as ethylene and ethanol, require methods to detect intermediates in multi-electron reduction processes involving C-C coupling reactions. Current C2 producing molecular catalysts are known to decompose during reactions, turning into metals and not fully utilizing their precisely controlled active sites. Therefore, developing structurally stable molecular catalysts during reactions is critical to understanding these mechanisms. In this study, we have demonstrated a Br-bridged copper dinuclear molecular catalyst with high robustness for CO2/CO reduction reactions, producing C3+ products including C3H7OH beyond C2 products. Operando XAFS and various spectroscopic analyses show that the dinuclear molecular catalyst maintains a stable Cu(I) state during the reduction reaction, preventing decomposition. Operando spectroscopic analysis using localized surface plasmon resonance identifies key C2 and C3 coupling intermediates essential for C3 production. Reaction intermediates obtained by 13CO2-labeled operando analysis were also corroborated. DFT calculations propose a mechanism where the reaction proceeds at room temperature to form C3 coupling species. The transition state structures resulting from this mechanistic analysis suggest that the progression of C-C coupling in the Cu dinuclear molecular metal complex is facilitated by the formation of a CO2/CO-reduced intermediate species that bridges the two Cu active sites. The bridging intermediate can adjust the Cu-Cu distance during the reaction, attracting reducing species to one Cu side and accepting substrate to the other Cu side. C3H7OH is formed through C-C coupling at the bridging site in flexible Cu binuclear structures. The discovery of a robust molecular catalyst for C3+ production provides a molecular design guideline for developing next-generation catalysts for multicarbon CO2 reduction products.

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24

Ghosh, Sujit, Kinkar Biswas, and Basudeb Basu. "Recent Advances in Microwave Promoted C-P Cross-coupling Reactions." Current Microwave Chemistry 7, no. 2 (August 6, 2020): 112–22. http://dx.doi.org/10.2174/2213335607666200401144724.

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: Organophosphorous compounds are of potential importance in diverse fields. They are often used as intermediates for making functionalized phosphine ligands as well as find vast applications in the areas of industrial, agricultural and biological chemistry. The microwave-assisted synthesis of C-P bonds has become increasingly popular because of its various advantages over conventional heating in the perspectives of green chemistry. : This review article has primarily focused on the synthesis of various organophosphorous molecules via microwave promoted C-P cross-coupling reactions under metal-catalyzed or metal–free conditions over the last two decades. The synthesis of phosphine ligands on 4,4′-bisquinolone structural framework, disubstituted phosphinic acid esters, vinyl phosphines, aryl- and vinylphosphonates, sugar and nucleoside phosphonates, aminobisphosphonates, triphenyl phosphines, water-soluble tertiary phosphine oxides and many other potentially useful organophosphorous compounds have been illustrated critically. The Hirao reaction, Michaelis-Arbuzov reaction and Sandmeyer type of reactions are generally involved in creating C-P bonds. The role of various metal catalysts, solvents, bases, additives and temperature in different literatures are carefully discussed.

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25

Torres, Gerardo M., Yi Liu, and Bruce A. Arndtsen. "A dual light-driven palladium catalyst: Breaking the barriers in carbonylation reactions." Science 368, no. 6488 (April 16, 2020): 318–23. http://dx.doi.org/10.1126/science.aba5901.

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Transition metal–catalyzed coupling reactions have become one of the most important tools in modern synthesis. However, an inherent limitation to these reactions is the need to balance operations, because the factors that favor bond cleavage via oxidative addition ultimately inhibit bond formation via reductive elimination. Here, we describe an alternative strategy that exploits simple visible-light excitation of palladium to drive both oxidative addition and reductive elimination with low barriers. Palladium-catalyzed carbonylations can thereby proceed under ambient conditions, with challenging aryl or alkyl halides and difficult nucleophiles, and generate valuable carbonyl derivatives such as acid chlorides, esters, amides, or ketones in a now-versatile fashion. Mechanistic studies suggest that concurrent excitation of palladium(0) and palladium(II) intermediates is responsible for this activity.

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26

Du, Yu, Yuhuang Wang, Xin Li, Yaling Shao, Guohui Li, Richard D. Webster, and Yonggui Robin Chi. "ChemInform Abstract: N-Heterocyclic Carbene Organocatalytic Reductive β,β-Coupling Reactions of Nitroalkenes via Radical Intermediates." ChemInform 46, no. 16 (April 2015): no. http://dx.doi.org/10.1002/chin.201516099.

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27

Zhang, Guang-Wei, Long Wang, Ling-Hai Xie, Xiao-Ya Hou, Zheng-Dong Liu, and Wei Huang. "Diarylfluorene-Based Shape-Persistent Organic Nanomolecular Frameworks via Iterative Friedel-Crafts Protocol toward Multicomponent Organic Semiconductors." Journal of Nanomaterials 2013 (2013): 1–8. http://dx.doi.org/10.1155/2013/368202.

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We describe bottom-up fluorenol approach to create soluble covalent organic nanomolecular architectures (ONAs) as potential multicomponent organic semiconductors (MOSs). BPyFBFFA as a typical model of ONAs and MOSs exhibits a persistent chair-shaped geometric structure that consists of hole-transporting triphenylamine (TPA), high-efficiency terfluorene, and high-mobility pyrenes. BPyFBFFA was synthesized via the intermediates PyFA and BPyFA with iterative Friedel-Crafts reactions and Suzuki cross-coupling reactions. BPyFBFFA behaves as an efficient blue light-emitter without the low-energy green emission band. Complex diarylfluorenes (CDAFs) are promising candidates for nanoscale covalent organic frameworks and MOSs. Friedel-Crafts protocols offer versatile toolboxes for molecular architects to frame chemistry and materials, nanoscience, and molecular nanotechnology as well as molecular manufactures.

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28

Ni, Hangcheng, Hui Mao, Ying Huang, Yi Lu, and Zhenxiang Liu. "Mild Iron-Catalyzed Oxidative Cross-Coupling of Quinoxalinones with Indoles." Molecules 29, no. 11 (June 4, 2024): 2649. http://dx.doi.org/10.3390/molecules29112649.

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Utilizing iron chloride as a Lewis acid catalyst, we developed a straightforward and mild oxidative cross-coupling reaction between quinoxalinones and indoles, yielding a series of versatile 3-(indol-3-yl)quinoxalin-2-one derivatives. This approach allows for the incorporation of a wide array of functional groups into the final products, demonstrating its synthetic versatility. Notably, the method was successfully scaled up to gram-scale reactions while maintaining high yields. Our mechanistic investigation indicates that iron chloride serves as a catalyst to facilitate the formation of key intermediates which subsequently undergo oxidation to afford the desired products. The merits of this protocol include its cost effectiveness, operational simplicity, and the ease of product isolation via filtration.

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29

Tan, Liquan, Cui Chen, and Weibing Liu. "α-Acetoxyarone synthesis via iodine-catalyzed and tert-butyl hydroperoxide-mediateded self-intermolecular oxidative coupling of aryl ketones." Beilstein Journal of Organic Chemistry 13 (June 6, 2017): 1079–84. http://dx.doi.org/10.3762/bjoc.13.107.

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We present a metal-free method for α-acetoxyarone synthesis by self-intermolecular oxidative coupling of aryl ketones using I2−tert-butyl hydroperoxide (TBHP). Under the optimum conditions, various aryl ketones gave the corresponding products in moderate to excellent yields. A series of control experiments were performed; the results suggest the involvement of radical pathways. Multiple radical intermediates were generated in situ and the overall process involved several different reactions, which proceeded self-sequentially in a single reactor. A labeling experiment using 18O-labeled H2O confirmed that the oxygen in the product was derived from TBHP, not from H2O in the TBHP solvent.

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30

Ramana, Govu, Gutam Madhu, Yerrabelli Jayaprakash Rao, and Chitneni Prasad Rao. "Design, Synthesis of 5-(2-Methylbenzofuran)-2-aryl-2H-tetrazole Derivatives via Cross-Coupling of N-H Free Tetrazoles with Boronic Acids." Asian Journal of Chemistry 35, no. 8 (2023): 2001–6. http://dx.doi.org/10.14233/ajchem.2023.28074.

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Chemical intermediates derived from 1,3-dipolar cycloaddition reactions, such as 5-substituted 1H-tetrazole, are commonly utilized to synthesize 1,5-disubstituted tetrazoles. In this work, a highly effective and useful strategy for the synthesis of 5-(2-methylbenzofuran-3-yl)-2-phenyl-2H-tetrazoles using environmentally safe 1 atm. O2 as oxidizer is reported. Moreover, the N-H unbound tetrazoles and low hazardous boronic acids are directly coupled with the catalytic amount (5 mol%) of Cu2O to form C-N bond without any formation of the additives. The proposed method is simple for the Cu-catalyzed reactions, which require only mild conditions and green, atom-efficient chemistry for the regioselective synthesis of 2,5-disubstituted 2H-tetrazoles.

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31

Ejjoummany, Abdelaziz, Jonathan Elie, Ahmed El Hakmaoui, Mohamed Akssira, Sylvain Routier, and Frédéric Buron. "Access and Modulation of Substituted Pyrrolo[3,4-c]pyrazole-4,6-(2H,5H)-diones." Molecules 28, no. 15 (August 1, 2023): 5811. http://dx.doi.org/10.3390/molecules28155811.

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The first access to polyfunctionnalized pyrrolo[3,4-c]pyrazole-4,6-(2H,5H)-dione derivatives is reported. The series were generated from diethyl acetylenedicarboxylate and arylhydrazines, which afforded the key intermediates bearing two functional positions. The annellation to generate the maleimide moiety of the bicycle was studied. Moreover, an efficient palladium-catalyzed C-C and C-N bond formation via Suzuki–Miyaura or Buchwald–Hartwig coupling reactions in C-6 position was investigated from 6-chloropyrrolo[3,4-c]pyrazole-4,6-(2H,5H)–diones. This method provides novel access to various 1,6 di-substituted pyrrolo[3,4-c] pyrazole-4,6-(2H,5H)–diones.

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32

Morimoto, Koji, Tomofumi Nakae, Nobutaka Yamaoka, Toshifumi Dohi, and Yasuyuki Kita. "Metal-Free Oxidative Coupling Reactions via σ-Iodonium Intermediates: The Efficient Synthesis of Bithiophenes Using Hypervalent Iodine Reagents." European Journal of Organic Chemistry 2011, no. 31 (September 14, 2011): 6326–34. http://dx.doi.org/10.1002/ejoc.201100969.

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33

Weinreb, Steven M. "Nitrosoalkenes: Underappreciated Reactive Intermediates for Formation of Carbon–Carbon Bonds." Synlett 30, no. 16 (July 22, 2019): 1855–66. http://dx.doi.org/10.1055/s-0037-1611899.

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This Account describes studies carried out by my group during the past decade on both intra- and intermolecular conjugate additions of carbon nucleophiles to nitrosoalkenes. Using the Denmark protocol for the generation of nitrosoalkenes from α-chloro-O-silyloximes, a number of bridged and fused bicyclic ring systems can be prepared via the intramolecular version of this process. Intermolecular conjugate addition reactions of nitrosoalkenes with a wide variety of ester enolates as coupling partners can also be achieved efficiently using a similar procedure. Some stereochemical aspects of these nucleophilic additions have been studied with both acyclic and cyclic nitrosoalkenes. This methodology has been applied as key steps in synthetic approaches to some complex indole and Myrioneuron alkaloids.1 Introduction2 Conjugate Additions of Nitrosoalkenes2.1 Background2.2 Intramolecular Reactions2.3 Intermolecular Reactions2.4 Stereochemical Aspects3 Applications to Natural Product Synthesis3.1 Angustilodine and Related Alkaloids3.2 Approach to Apparicine-Type Alkaloids3.3 Myrioneurinol4 Summary and Outlook

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34

Ogawa, Akiya, Taichi Tamai, Takenori Mitamura, and Akihiro Nomoto. "Highly selective introduction of heteroatom groups to isocyanides and its application to electrocyclic reactions." Pure and Applied Chemistry 85, no. 4 (December 7, 2012): 785–99. http://dx.doi.org/10.1351/pac-con-12-07-01.

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Photoinduced cyclization of o-alkenylaryl isocyanides with (PhS)2 in the presence of (PhTe)2 affords the corresponding bisthiolated indene derivatives in good yields via radical cyclization process by thio radical. The procedure can be applied to the construction of tetracyclic systems by using bis(o-aminophenyl) disulfides in place of (PhS)2. In sharp contrast, when o-alkynylaryl isocyanides are employed as the substrates, novel electrocyclic reactions take place upon photoirradiation or heating at 40~80 °C to generate quinoline 2,4-biradical species, which are trapped with organic diselenides, ditellurides, and molecular iodine to give the corresponding 2,4-diseleno-, ditelluro-, and diiodo-quinoline derivatives, respectively, in good yields. The obtained quinoline derivatives are useful synthetic intermediates; for example, cross-coupling reactions using 2,4-diiodoquinolines lead to the preparation of functionalized quinoline derivatives.

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35

Morimoto, Koji, Tomofumi Nakae, Nobutaka Yamaoka, Toshifumi Dohi, and Yasuyuki Kita. "ChemInform Abstract: Metal-Free Oxidative Coupling Reactions via σ-Iodonium Intermediates: The Efficient Synthesis of Bithiophenes Using Hypervalent Iodine Reagents." ChemInform 43, no. 11 (February 16, 2012): no. http://dx.doi.org/10.1002/chin.201211085.

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36

Nikol’skiy, Vladislav V., Mikhail E. Minyaev, Maxim A. Bastrakov, and Alexey M. Starosotnikov. "Straightforward and Efficient Protocol for the Synthesis of Pyrazolo [4,3-b]pyridines and Indazoles." International Journal of Molecular Sciences 24, no. 2 (January 16, 2023): 1758. http://dx.doi.org/10.3390/ijms24021758.

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An efficient method for the synthesis of pyrazolo [4,3-b]pyridines has been developed on the basis of readily available 2-chloro-3-nitropyridines via a sequence of SNAr and modified Japp–Klingemann reactions. The method offers a number of advantages including utilization of stable arenediazonium tosylates, operational simplicity as well as combining the azo-coupling, deacylation and pyrazole ring annulation steps in a one-pot manner. An unusual rearrangement (C-N-migration of the acetyl group) was observed and a plausible mechanism was proposed based on the isolated intermediates and NMR experiments. In addition, the developed protocol was successfully applied to the synthesis of 1-arylindazoles combining the Japp–Klingemann reaction and cyclization of the resulting hydrazone as a one-pot procedure.

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37

Luo, Zhongyang, Longyi Liu, Feiting Miao, Wanchen Zhu, Longfei Li, and Yuanlin Wang. "Electron Paramagnetic Resonance in Lignocellulosic Biomass Pyrolysis Mechanism: Advancements, Applications, and Prospects." Energies 18, no. 7 (March 23, 2025): 1598. https://doi.org/10.3390/en18071598.

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Lignocellulosic biomass can be converted into high-value-added bio-based materials through pyrolysis; however, an unclear pyrolysis mechanism hinders its further application. Electron paramagnetic resonance (EPR) spectroscopy is the most common technology for detecting radicals, which are important intermediates of bond-breaking reactions and coupling reactions during pyrolysis. Hence, this article provides a dedicated review of recent applications, limitations, and prospects of EPR for lignocellulosic biomass pyrolysis. It starts with the advancements of EPR, including EPR spectroscopy principles, radical trapping methods, and spectrum analysis. This review establishes the radical-mediated reaction pathway spanning model compounds to native lignocellulosic biomass, via detecting and identifying the key radicals in the pyrolysis process and pyrolysis products. Furthermore, the effect of biomass pretreatment on the radical behavior during pyrolysis has been emphasized. By providing a comprehensive review of radical evolutionary patterns during biomass pyrolysis using EPR, we conclude with limitations and prospects, which may offer a new perspective on the mechanism of biomass pyrolysis and the optimization of pyrolysis conditions.

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38

Almohaywi, Basmah, Tsz Tin Yu, George Iskander, Shekh Sabir, Mohan Bhadbhade, David StC Black, and Naresh Kumar. "Synthesis of Alkyne-Substituted Dihydropyrrolones as Bacterial Quorum-Sensing Inhibitors of Pseudomonas aeruginosa." Antibiotics 11, no. 2 (January 25, 2022): 151. http://dx.doi.org/10.3390/antibiotics11020151.

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The Quorum-sensing system in Pseudomonas aeruginosa is responsible for the pathogenicity and the production of virulence factors and biofilm formation. Dihydropyrrolones were previously found to act as inhibitors of QS-dependent bacterial phenotypes. In this study, a range of dihydropyrrolone (DHP) analogues was synthesized via the lactone-lactam conversion of lactone intermediates followed by the formation of novel acetylene analogues of dihydropyrrolones from brominated dihydropyrrolones via Sonogashira coupling reactions in moderate to high yields. Upon biological testing, the most potent compounds, 39–40 and 44, showed higher bacterial quorum-sensing inhibitory (QSI) activity against P. aeruginosa reporter strain at 62.5 µM. Structure–activity relationship studies revealed that di-alkynyl substituent at the exocyclic position of DHPs possessed higher QSI activities than those of mono-alkynyl DHPs. Moreover, a hexyl-substituent at C3 of DHPs was beneficial to QSI activity while a phenyl substituent at C4 of DHPs was detrimental to QSI activity of analogues.

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39

Hu, Min, Dianfan Liu, Yuan Liu, Fan Luo, Xiaobei Chen, Yuejia Yin, Shilei Zhang, and Yanwei Hu. "The Reaction of Aryl Thiols or Thioureas with <i>o</i>‐Diiodoarenes/NaH to Access o‐Iodoaryl Thioethers." Advanced Synthesis & Catalysis, February 7, 2024. http://dx.doi.org/10.1002/adsc.202301426.

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Herein we report a method for the synthesis of thioethers by forging C(aryl)‐S bond via an aryne mechanism. The active aryne species can be generated from o‐diiodoarenes and NaH in THF at room temperature, then lead to the arylations of a wide range of aryl thiols and thioureas. Different from transition metal‐catalyzed cross‐coupling reactions, no disubstituted byproduct is formed in our protocol. The o‐iodoaryl thioether products are intermediates that could be transformed into pharmaceutically interesting molecules.

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40

Plasek, Erin E., Brylon N. Denman, and Courtney C. Roberts. "Insights into the Regioselectivity of Metal-Catalyzed Aryne Reactions." Synlett, September 18, 2023. http://dx.doi.org/10.1055/s-0042-1751487.

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AbstractThe synthetic potential of unsymmetrically substituted aryne intermediates is significantly hindered by regioselectivity issues. Current methods for inducing regioselectivity all rely on substrate control and are focused on non-metallated arynes. Before our initial disclosure, there was no systematic study regarding the regioselectivity of metal-catalyzed aryne reactions. By exploiting ligand control, we have induced regioselectivity in a palladium-catalyzed aryne annulation to form phenanthridinones (up to 9:91 r.r.). Through this study we have investigated: ligand effects, influence of steric perturbation, and the impact of the aryne precursor.1 Introduction2 Inducing Regioselectivity via Ligand Control3 A Comparison of o-Borylaryl Triflate Aryne Precursors to Kobayashi Aryne Precursors4 Conclusion

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41

Hazarika, Hemanta, and Pranjal Gogoi. "Access to diverse organosulfur compounds via aryne: A comprehensive review on Kobayashi’s aryne precursor." Organic & Biomolecular Chemistry, 2021. http://dx.doi.org/10.1039/d1ob01436f.

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Arynes are highly reactive transient intermediates having enormous applications in organic synthesis. In the last three decades aryne chemistry has shown incredible developments in carbon-carbon and carbon-heteroatom bond formation reactions....

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42

Hoshi, Yukitaka, Shinya Tabata, and Suguru Yoshida. "Synthesis of α-arylacetophenone derivatives by Grignard reactions and transformations of arynes via C–C bond cleavage." Chemical Communications, 2025. https://doi.org/10.1039/d4cc06769j.

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Divergent synthesis of α-arylacetophenones by 1,2-addition and subsequent transformations via aryne intermediates is disclosed. The choice of solvent played a critical role in the efficient synthesis of benzocyclobutenols by the...

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43

Kevorkian, Paul V., Dorian S. Sneddon, Casey B. Ritts, and Thomas R. Hoye. "Phosphorane‐Promoted C–C Coupling during Aryne Annulations." Angewandte Chemie, February 7, 2024. http://dx.doi.org/10.1002/ange.202318774.

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Abstract: Arynes are fleeting, high‐energy intermediates that undergo myriad trapping reactions by nucleophiles. Their unusual reactivity compared to other electrophiles can spur unexpected mechanistic pathways enroute to the formation of benzenoid products. Herein we explore a particularly unique case of thermally generated arynes reacting with phosphoranes to form helical dibenzothiophenes and ‐selenophenes. Multiple new helical polycyclic aromatic products are reported. DP4+ and X‐ray crystallographic analysis were used in tandem to confirm the structural topologies of selected products and to demonstrate the utility of DP4+ for distinguishing between isomeric polycyclic aromatic compounds. Lastly, we discuss a plausible mechanism consistent with DFT computations that accounts for the product formation; namely, ligand coupling (i.e., reductive elimination) within a hypervalent, pentacarbon‐ligated s‐phosphorane furnishes the dibenzothio‐ or dibenzoselenophene.

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44

Kevorkian, Paul V., Dorian S. Sneddon, Casey B. Ritts, and Thomas R. Hoye. "Phosphorane‐Promoted C–C Coupling during Aryne Annulations." Angewandte Chemie International Edition, February 7, 2024. http://dx.doi.org/10.1002/anie.202318774.

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Abstract: Arynes are fleeting, high‐energy intermediates that undergo myriad trapping reactions by nucleophiles. Their unusual reactivity compared to other electrophiles can spur unexpected mechanistic pathways enroute to the formation of benzenoid products. Herein we explore a particularly unique case of thermally generated arynes reacting with phosphoranes to form helical dibenzothiophenes and ‐selenophenes. Multiple new helical polycyclic aromatic products are reported. DP4+ and X‐ray crystallographic analysis were used in tandem to confirm the structural topologies of selected products and to demonstrate the utility of DP4+ for distinguishing between isomeric polycyclic aromatic compounds. Lastly, we discuss a plausible mechanism consistent with DFT computations that accounts for the product formation; namely, ligand coupling (i.e., reductive elimination) within a hypervalent, pentacarbon‐ligated s‐phosphorane furnishes the dibenzothio‐ or dibenzoselenophene.

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45

Shintani, Ryo. "Synthesis of cyclic organosilicon compounds by palladium-catalyzed reactions of 2-silylaryl triflates." Chemistry Letters, July 16, 2024. http://dx.doi.org/10.1093/chemle/upae132.

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Abstract 2-Silylaryl triflates are widely employed as effective aryne precursors in organic synthesis, but their use as substrates for the synthesis of organosilicon compounds by retaining their silicon substituents is another attractive usage of these reagents. In particular, cyclic compounds having a silicon atom in the ring are promising candidates for various biologically active substances and optoelectronic functional materials. In this context, new synthetic methods of silicon-containing cyclic compounds have been actively investigated through the development of palladium-catalyzed reactions of 2-silylaryl triflates without generating aryne intermediates. As a result, selective synthesis of various silacyclic compounds has been achieved via C–H and/or C–Si bond activations as well as intramolecular exchange between these bonds and C–Pd bonds that are formed as reaction intermediates. An overview of this topic is described including the mechanistic insights.

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46

Dong, Yuyang, Michael I. Lipschutz, and T. Don Tilley. "ChemInform Abstract: Regioselective, Transition Metal-Free C-O Coupling Reactions Involving Aryne Intermediates." ChemInform 47, no. 32 (July 2016). http://dx.doi.org/10.1002/chin.201632072.

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47

Duez, Quentin, Lukáš Marek, Jiří Váňa, Jiří Hanusek, and Jana Roithová. "Autocatalysis in Eschenmoser Coupling Reactions." Chemistry – A European Journal, December 13, 2023. http://dx.doi.org/10.1002/chem.202303619.

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The Eschenmoser coupling reaction (ECR) of thioamides with electrophiles is believed to proceed via thiirane intermediates. However, little is known about converting the intermediates into ECR products. Previous mechanistic studies involved external thiophiles to remove the sulfur atom from the intermediates. In this work, an ECR proceeding without any thiophilic agent or base is studied by electrospray ionization‐mass spectrometry. ESI‐MS enables the detection of the so‐far elusive polysulfide species Sn, with n ranging from 2 to 16 sulfur atoms, proposed to be the key species leading to product formation. Integrating observations from ion mobility spectrometry, ion spectroscopy, and reaction monitoring via flow chemistry coupled with mass spectrometry provides a comprehensive understanding of the reaction mechanism and uncovers the autocatalytic nature of the ECR reaction.

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48

Tan, Jiajing, Ruirui Zhang, and Xia Peng. "Recent Advances in Construction of C(sp2)–O Bonds via Aryne Participated Multicomponent Coupling Reactions." Synthesis, January 24, 2022. http://dx.doi.org/10.1055/a-1748-7448.

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AbstractAryne chemistry is a powerful synthetic technique that forms new bonds to aromatic rings. The recent resurgence of aryne-based multicomponent coupling strategies has led to an influx of methodologies for the mild synthesis of arene derivatives. In particular, these innovative discoveries broaden and streamline approaches toward phenol ether motifs, which are a prevalent structural component across a broad range of chemistry related research fields. Herein, this review aims to provide a comprehensive overview of the recent progress in the construction of C(sp2)–O bonds via aryne-induced multicomponent reactions. Special attention has been paid to reaction design and mechanistic pathways.1 Introduction2 Insertion-Based MCRs3 Nucleophilic-Addition-Based MCRs4 Cycloaddition-Based MCRs5 Summary

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49

Kazmaier, Uli, and Matthias Pohlman. "Cross-Coupling Reactions via π-Allyl Metal Intermediates." ChemInform 36, no. 30 (July 26, 2005). http://dx.doi.org/10.1002/chin.200530251.

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50

Hu, Panjie, Lingfei Hu, Xiao-Xi Li, MengXIao Pan, Gang Lu, and Xingwei Li. "Rhodium(I)‐Catalyzed Asymmetric Hydroarylative Cyclization of 1,6‐Diynes to Access Atropisomerically Labile Chiral Dienes." Angewandte Chemie, November 16, 2023. http://dx.doi.org/10.1002/ange.202312923.

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Axially chiral open‐chained olefins are an underexplored class of atropisomers, whose enantioselective synthesis represents a daunting challenge due to their relatively low racemization barrier. We herein report rhodium(I)‐catalyzed hydroarylative cyclization of 1,6‐diynes with three distinct classes of arenes, enabling highly enantioselective synthesis of a broad range of axially chiral 1,3‐dienes that are conformationally labile (delta G activation (rac) = 26.6‐28.0 kcal/mol). The coupling reactions in each category proceeded with excellent enantioselectivity, regioselectivity, and Z/E selectivity under mild reaction conditions. Computational studies of the coupling of quinoline N‐oxide system indicate that the reaction proceeds via initial oxidative cyclization of the 1,6‐diyne to give a rhodacyclic intermediate, followed by sigma‐bond metathesis between the arene C‐H bond and the Rh‐C(vinyl) bond, with subsequent C‐C reductive elimination being enantio‐determining and turnover‐limiting. The DFT‐established mechanism is consistent with the experimental studies. Significantly, the coupled products of quinoline N‐oxides undergo facile visible light‐induced intramolecular oxygen‐atom transfer, affording chiral epoxides with complete axial‐to‐central chirality transfer.

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