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Ghosh A, Pawar AB. Harnessing sulfilimine as an oxidizing directing group in Cp*Co(III)-catalyzed [4+2] annulation with alkynes and 1,3-diynes. Chem Commun (Camb) 2025; 61:8240-8243. [PMID: 40337886 DOI: 10.1039/d5cc01230a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/09/2025]
Abstract
We have developed the first Cp*Co(III)-catalyzed [4+2] annulation utilizing sulfilimine as an oxidizing directing group in a redox-neutral fashion. The N-S bond of the sulfilimine serves as an internal oxidant, thereby eliminating the need for any internal oxidant. The reaction worked with various alkynes and also exhibited an excellent regioselectivity with 1,3-diynes furnishing the 3-alkynylated isoquinolones.
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Affiliation(s)
- Arijit Ghosh
- School of Chemical Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, 175005, India.
| | - Amit B Pawar
- School of Chemical Sciences, Indian Institute of Technology Mandi, Mandi, Himachal Pradesh, 175005, India.
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Zhao G, Xue K, Dong H, Lou S, Zhang X, Cao Z, Yi B, Tong R. Bromide as Noninnocent Ligand to Iron Tames Fenton Chemistry for Chemoselective Nondegrading Oxidation. Angew Chem Int Ed Engl 2025:e202505907. [PMID: 40308005 DOI: 10.1002/anie.202505907] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/13/2025] [Revised: 04/14/2025] [Accepted: 04/29/2025] [Indexed: 05/02/2025]
Abstract
It has long been the chemistry dogma that the nitrogen-based ligand of iron complexes determines the redox reactivity; tetra- and/or pentadentate nitrogen-based ligand (N-ligand: PDP, porphyrin, N4Py) enables chemo-selective oxidation through high-valent iron species (FeIV/V═O), while bi- and/or tridentate N-ligand leads to the generation of highly reactive oxygen species (ROS) (i.e., hydroxyl radical) via a Fenton chemistry pathway. The effect of inorganic anionic ligands (i.e., halides, pseudohalides, triflate, nitrate, sulfate, etc) of these iron complexes has rarely been examined and overlooked as an "innocent" anion. Herein, we report our discovery that bromide (Br-) is not an innocent ligand to the iron-BPMA complexes [BMPA: bis(2-pyridylmethyl)amine] but a decisive factor for taming the Fenton chemistry (ROS) into a mild [HOBr] oxidant, which allows for chemo- and regioselective oxidation of furans, indoles, and sulfides without noticeable degradation. In contrast to the conventional Fenton chemistry pathway by many tridentate N-ligand iron complexes, our [Fe(BMPA)Br3] mimics haloperoxidases to generate HOBr by oxidation of bromide ion with hydrogen peroxide. The discovery of the bromide effect on iron complexes bridges the gap between Fenton chemistry and haloperoxidase-catalyzed halogenation and might stimulate interest in reinvestigating the "innocent" ligand of iron complexes for discovery of new reactivity and new applications. Additionally, the new catalytic system represents a mild and green oxidation method that might be useful in academia and industry.
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Affiliation(s)
- Guodong Zhao
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
- Engineering Research Center for Pharmaceutics of Chinese Materia Medica and New Drug Development, Ministry of Education, Beijing, China
| | - Kang Xue
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Huiling Dong
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Shaoyan Lou
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Xiaohui Zhang
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Zhuo Cao
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Bingqing Yi
- School of Chinese Materia Medica, Beijing University of Chinese Medicine, Beijing, 102488, China
| | - Rongbiao Tong
- Department of Chemistry, The Hong Kong University of Science and Technology, Clearwater Bay, Kowloon, Hong Kong, China
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Xu F, Zhang SY, Li YP, Huo JQ, Zeng FW. Transition metal-catalyzed cascade C-H activation/cyclization with alkynes: an update on sulfur-containing directing groups. Chem Commun (Camb) 2025; 61:1729-1747. [PMID: 39714315 DOI: 10.1039/d4cc05807k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/24/2024]
Abstract
In light of the extensive applications of sulfur-containing heterocyclic compounds in drug discovery, agrochemicals, and advanced materials, the construction of complex sulfur-containing molecular scaffolds has flourished in recent years. There is a profound interest in synthetic methods for forming carbon-sulfur bonds. Regarding this, transition metal (TM)-catalyzed C-H bond activation has emerged as a valuable means for the rapid formation of C-S bonds, although it is comparatively less explored than C-N or C-C bonds. The research significance of sulfur-directed C-H activation chemistry lies in maintaining a balance between activating and poisoning the catalyst as well as in the diversity and novelty of its properties. This review centers on sulfur-directed TM-catalyzed cascade C-H activation/cyclization with alkyne and encompasses the literature mainly from 2012 to 2024. The widely acknowledged reactivity and versatility of rhodium, ruthenium, and cobalt catalysts have given rise to various captivating cascade processes. For most reactions illustrated in this review, reactivity and selectivity are attained through the flexible synergistic combination of different metal catalysts and additives. Further advancements will be accompanied with the discovery of innovative sulfur-directing groups, chiral catalysis, and ground-breaking experimental techniques. This article will also inspire researchers to gain a deeper understanding of the mechanism, thus undoubtedly leading to innovations and more discoveries in the future.
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Affiliation(s)
- Fen Xu
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China.
| | - Shi-Yu Zhang
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China.
| | - Ya-Peng Li
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China.
| | - Jia-Qi Huo
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China.
| | - Fan-Wang Zeng
- Department of Material and Chemical Engineering, Zhengzhou University of Light Industry, Zhengzhou 450002, P. R. China.
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Luo Y, Zhang M, Xia Y. Isatoic anhydride as a masked directing group and internal oxidant for Rh(III)-catalyzed decarbonylative annulation through C-H activation: insights from DFT calculations. Chem Commun (Camb) 2024; 60:12770-12773. [PMID: 39400304 DOI: 10.1039/d4cc03733b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 10/15/2024]
Abstract
Density functional theory calculations uncovered a new mechanism for the rhodium-catalyzed decarbonylative annulation of isatoic anhydride with alkynes, in which the acyloxy group formed from the N-H deprotonation and C-O bond cleavage of isatoic anhydride acts as the directing group to assist the ortho C-H activation. From the generated five-membered rhodacycle intermediate, the final aminoisocoumarin product could be formed by subsequent steps of alkyne insertion, reductive elimination, decarbonylation, and protonation. The isocyanate moiety contained in the annulation intermediate was uncovered as a novel internal oxidant for the reaction, which oxidizes the Rh(I) to Rh(III) by decarbonylation.
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Affiliation(s)
- Yanshu Luo
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
| | - Maosheng Zhang
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
| | - Yuanzhi Xia
- College of Chemistry and Materials Engineering, Wenzhou University, Wenzhou 325035, China.
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Zhu H, Sun D, Zhang S, Chen J, Xu Z. Rhodium-Catalyzed Pyridylation of Alkynamides with Pyridylboronic Acids: A Route to Functionalized Enamides. Chemistry 2024; 30:e202401830. [PMID: 39037552 DOI: 10.1002/chem.202401830] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/10/2024] [Revised: 07/19/2024] [Accepted: 07/22/2024] [Indexed: 07/23/2024]
Abstract
The catalytic direct hydroarylation of alkynamides is a highly efficient approach for accessing functionalized trisubstituted arylalkenes with amide groups. Herein, we report a rhodium-catalyzed pyridylation of alkynamides with pyridylboronic acids, producing a variety of primary, secondary, and tertiary enamides with high yields (up to 94 %). This reaction demonstrates broad tolerance towards various alkyl and aryl functional groups, providing convenient access to a diverse array of alkenylpyridine derivatives. To demonstrate potential applications in late-stage hydropyridylation, we synthesized α,β-unsaturated ketones, aldehydes, and esters with high yields from the pyridylation product of Weinreb amides. This indirect expansion of the substrate scope enhances the practicality of this strategy. Additionally, the α,β-unsaturated ketone obtained can be further reduced to yield a chiral alcohol with a 99 % ee, further demonstrating the versatility and potential utility of this approach.
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Affiliation(s)
- Huilong Zhu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Dingcheng Sun
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Shengxiang Zhang
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Junning Chen
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
| | - Zhou Xu
- Jiangsu Key Laboratory of New Drug Research and Clinical Pharmacy, School of Pharmacy, Xuzhou Medical University, Xuzhou, China
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