1
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Liu XR, Cui PF, García-Rodeja Y, Solà M, Jin GX. Formation and reactivity of a unique M⋯C-H interaction stabilized by carborane cages. Chem Sci 2024; 15:9274-9280. [PMID: 38903214 PMCID: PMC11186334 DOI: 10.1039/d4sc01158a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/19/2024] [Accepted: 05/16/2024] [Indexed: 06/22/2024] Open
Abstract
Broadening carborane applications has consistently been the goal of chemists in this field. Herein, compared to alkyl or aryl groups, a carborane cage demonstrates an advantage in stabilizing a unique bonding interaction: M⋯C-H interaction. Experimental results and theoretical calculations have revealed the characteristic of this two-center, two-electron bonding interaction, in which the carbon atom in the arene ring provides two electrons to the metal center. The reduced aromaticity of the benzene moiety, long distance between the metal and carbon atom in arene, and the upfield shift of the signal of M⋯C-H in the nuclear magnetic resonance spectrum distinguished this interaction from metal⋯C π interaction and metal-C(H) σ bonds. Control experiments demonstrate the unique electronic effects of carborane in stabilizing the M⋯C-H bonding interaction in organometallic chemistry. Furthermore, the M⋯C-H interaction can convert into C-H bond metallization under acidic conditions or via treatment with t-butyl isocyanide. These findings deepen our understanding regarding the interactions between metal centers and carbon atoms and provide new opportunities for the use of carboranes.
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Affiliation(s)
- Xin-Ran Liu
- State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University 2005 Songhu Road Shanghai 200433 P. R. China
| | - Peng-Fei Cui
- State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University 2005 Songhu Road Shanghai 200433 P. R. China
| | - Yago García-Rodeja
- Institut de Química Computacional i Catàlisi, Departament de Química, Universitat de Girona C/Maria Aurèlia Capmany, 69 17003 Girona Spain
| | - Miquel Solà
- Institut de Química Computacional i Catàlisi, Departament de Química, Universitat de Girona C/Maria Aurèlia Capmany, 69 17003 Girona Spain
| | - Guo-Xin Jin
- State Key Laboratory of Molecular Engineering of Polymers, Shanghai Key Laboratory of Molecular Catalysis and Innovative Materials, Department of Chemistry, Fudan University 2005 Songhu Road Shanghai 200433 P. R. China
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2
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Ki Au Y, Ma Q, Zhang J, Xie Z. Ir-Catalyzed B(3)-Amination of o-Carboranes with Amines via Acceptorless Dehydrogenative BH/NH Cross-Coupling. Chem Asian J 2023; 18:e202300611. [PMID: 37694997 DOI: 10.1002/asia.202300611] [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: 07/14/2023] [Revised: 09/09/2023] [Accepted: 09/11/2023] [Indexed: 09/12/2023]
Abstract
An efficient and convenient strategy for Ir-catalyzed selective B(3)-amination of o-carboranes with amines via acceptorless BH/NH dehydrocoupling was developed, affording a series of B(3)-aminated-o-carboranes in moderate to high isolated yields with H2 gas as a sole by-product. Such an oxidant-free system endues the protocol sustainability, atom-economy and environmental friendliness. A reaction mechanism via an Ir(I)-Ir(III)-Ir(I) catalytic cycle involving oxidative addition, dehydrogenation and reductive elimination was proposed.
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Affiliation(s)
- Yik Ki Au
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin, N.T., Hong Kong, P.R. China
| | - Qiangqiang Ma
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin, N.T., Hong Kong, P.R. China
| | - Jie Zhang
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin, N.T., Hong Kong, P.R. China
| | - Zuowei Xie
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong Shatin, N.T., Hong Kong, P.R. China
- Shenzhen Grubbs Institute and Department of Chemistry, Southern University of Science and Technology, Shenzhen, 518055, P.R.China
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3
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Xie F, Mao Z, Curran DP, Liang H, Dai W. Facile Borylation of Alkenes, Alkynes, Imines, Arenes and Heteroarenes with N-Heterocyclic Carbene-Boranes and a Heterogeneous Semiconductor Photocatalyst. Angew Chem Int Ed Engl 2023; 62:e202306846. [PMID: 37555790 DOI: 10.1002/anie.202306846] [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: 05/16/2023] [Revised: 08/08/2023] [Accepted: 08/09/2023] [Indexed: 08/10/2023]
Abstract
Although the development of radical chain and photocatalytic borylation reactions using N-heterocyclic carbene (NHC)-borane as boron source is remarkable, the persistent problems, including the use of hazardous and high-energy radical initiators or the recyclability and photostability issues of soluble homogeneous photocatalysts, still leave great room for further development in a sustainable manner. Herein, we report a conceptually different approach toward highly functionalized organoborane synthesis by using recoverable ultrathin cadmium sulfide (CdS) nanosheets as a heterogeneous photocatalyst, and a general and mild borylation platform that enables regioselective borylation of a wide variety of alkenes (arylethenes, trifluoromethylalkenes, α,β-unsaturated carbonyl compounds and nitriles), alkynes, imines and electron-poor aromatic rings with NHC-borane as boryl radical precursor. Mechanistic studies and density functional theory (DFT) calculations reveal that both photogenerated electrons and holes on the CdS fully perform their own roles, thereby resulting in enhancement of photocatalytic activity and stability of CdS.
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Affiliation(s)
- Fukai Xie
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Zhan Mao
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Dennis P Curran
- Department of Chemistry, University of Pittsburgh, Pittsburgh, PA, 15208, USA
| | - Hongliang Liang
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
| | - Wen Dai
- Dalian Institute of Chemical Physics, Chinese Academy of Sciences, Dalian, 116023, China
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4
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Zhang QS, He L, Liu Q, Chen XY. Charge Transfer Complex-Enabled Synthesis of (Hetero)arylated m-Carboranes from m-Carborane Phosphonium Salts. Org Lett 2023; 25:5768-5773. [PMID: 37534925 DOI: 10.1021/acs.orglett.3c01989] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/04/2023]
Abstract
A photoinduced charge transfer complex (CTC)-enabled photoreduction of carborane phosphonium salts for the cage carbon (hetero)arylation of carboranes was developed. It offers a convenient approach for introducing a wide range of aryl and heteroaryl groups, such as pyrroles, thiophenes, indoles, thianaphthenes, benzofurans, pyridines, and benzenes, into carboranes. This strategy offers operational simplicity, mild reaction conditions, and a broad substrate scope, making it highly advantageous.
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Affiliation(s)
- Qing-Shuang Zhang
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, Xinjiang 832000, People's Republic of China
| | - Lin He
- Key Laboratory for Green Processing of Chemical Engineering of Xinjiang Bingtuan, School of Chemistry and Chemical Engineering, Shihezi University, Shihezi, Xinjiang 832000, People's Republic of China
| | - Qiang Liu
- School of Chemical Sciences, University of the Chinese Academy of Sciences, Beijing 100049, China
| | - Xiang-Yu Chen
- School of Chemical Sciences, University of the Chinese Academy of Sciences, Beijing 100049, China
- Binzhou Institute of Technology, Weiqiao-UCAS Science and Technology Park, Binzhou 256606, China
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5
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Ren H, Zhang P, Xu J, Ma W, Tu D, Lu CS, Yan H. Direct B-H Functionalization of Icosahedral Carboranes via Hydrogen Atom Transfer. J Am Chem Soc 2023; 145:7638-7647. [PMID: 36946888 DOI: 10.1021/jacs.3c01314] [Citation(s) in RCA: 7] [Impact Index Per Article: 7.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/23/2023]
Abstract
The efficient and selective functionalization of icosahedral carboranes (C2B10H12) at the boron vertexes is a long-standing challenge owing to the presence of 10 inert B-H bonds in a similar chemical environment. Herein, we report a new reaction paradigm for direct B-H functionalization of icosahedral carboranes via B-H homolysis enabled by a nitrogen-centered radical-mediated hydrogen atom transfer (HAT) strategy. Both the HAT process of the carborane B-H bond and the resulting boron-centered carboranyl radical intermediate have been confirmed experimentally. The reaction occurs at the most electron-rich boron vertex with the lowest B-H bond dissociation energy (BDE). Using this strategy, diverse carborane derivatization, including thiolation, selenation, alkynylation, alkenylation, cyanation, and halogenation, have been achieved in satisfactory yields under a photoinitiated condition in a metal-free and redox-neutral fashion. Moreover, the synthetic utility of the current protocol was also demonstrated by both the scale-up reaction and the construction of carborane-based functional molecules. Therefore, this methodology opens a radical pathway to carborane functionalization, which is distinct from the B-H heterolytic mechanism in the traditional strategies.
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Affiliation(s)
- Hongyuan Ren
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Ping Zhang
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Jingkai Xu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Wenli Ma
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Deshuang Tu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Chang-Sheng Lu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
| | - Hong Yan
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing 210023, China
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6
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Peng TY, Zhang FL, Wang YF. Lewis Base-Boryl Radicals Enabled Borylation Reactions and Selective Activation of Carbon-Heteroatom Bonds. Acc Chem Res 2023; 56:169-186. [PMID: 36571794 DOI: 10.1021/acs.accounts.2c00752] [Citation(s) in RCA: 12] [Impact Index Per Article: 12.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/27/2022]
Abstract
ConspectusThe past decades have witnessed tremendous progress on radical reactions. However, in comparison with carbon, nitrogen, oxygen, and other main group element centered radicals, the synthetic chemistry of boron centered radicals was less studied, mainly due to the high electron-deficiency and instability of such 3-center-5-electron species. In the 1980s, Roberts and co-workers found that the coordination of a Lewis base (amines or phosphines) with the boron center could form 4-center-7-electron boryl radicals (Lewis base-boryl radicals, LBRs) that are found to be more stable. However, only limited synthetic applications were developed. In 2008, Curran and co-workers achieved a breakthrough with the discovery of N-heterocyclic carbene (NHC) boryl radicals, which could enable a range of radical reduction and polymerization reactions. Despite these exciting findings, more powerful and valuable synthetic applications of LBRs would be expected, given that the structures and reactivities of LBRs could be easily modulated, which would provide ample opportunities to discover new reactions. In this Account, a summary of our key contributions in LBR-enabled radical borylation reactions and selective activation of inert carbon-heteroatom bonds will be presented.Organoboron compounds have shown versatile applications in chemical society, and their syntheses rely principally on ionic borylation reactions. The development of mechanistically different radical borylation reactions allows synthesizing products that are inaccessible by traditional methods. For this purpose, we progressively developed a series of NHC-boryl radical mediated chemo-, regio-, and stereoselective radical borylation reactions of alkenes and alkynes, by which a wide variety of structurally diverse organoboron molecules were successfully prepared. The synthetic utility of these borylated products was also demonstrated. Furthermore, we disclosed a photoredox protocol for oxidative generation of NHC-boryl radicals, which enabled useful defluoroborylation and arylboration reactions.Selective bond activation is an ideal way to convert simple starting materials to value-added products, while the cleavage of inert chemical bonds, in particular the chemoselectivity control when multiple identical bonds are present in similar chemical environments, remains a long-standing challenge. We envisaged that finely tuning the properties of LBRs might provide a new solution to address this challenge. Recently, we disclosed a 4-dimethylaminopyridine (DMAP)-boryl radical promoted sequential C-F bond functionalization of trifluoroacetic acid derivatives, in which the α-C-F bonds were selectively snipped via a spin-center shift mechanism. This strategy enables facile conversion of abundantly available trifluoroacetic acid to highly valuable mono- and difluorinated molecules. Encouraged by this finding, we further developed a boryl radical enabled three-step sequence to construct all-carbon quaternary centers from a range of trichloromethyl groups, where the three C-Cl bonds were selectively cleaved by the rational choice of suitable boryl radical precursors in each step. Furthermore, a boryl radical promoted dehydroxylative alkylation of α-hydroxy carboxylic acid derivatives was achieved, allowing for the efficient conversion of some biomass platform molecules to high value products.
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Affiliation(s)
- Tian-Yu Peng
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026 Anhui, China
| | - Feng-Lian Zhang
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026 Anhui, China
| | - Yi-Feng Wang
- Hefei National Research Center for Physical Sciences at the Microscale, Department of Chemistry, University of Science and Technology of China, 96 Jinzhai Road, Hefei, 230026 Anhui, China.,State Key Laboratory of Elemento-Organic Chemistry, Nankai University, 94 Weijin Road, Tianjin 300071, China
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7
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Lu W, Wu Y, Ma YN, Chen F, Chen X. A Method for Highly Selective Halogenation of o-Carboranes and m-Carboranes. Inorg Chem 2023; 62:885-892. [PMID: 36584667 DOI: 10.1021/acs.inorgchem.2c03694] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/31/2022]
Abstract
A facile halogenation method for highly selective synthesis of 9-X-o-carboranes, 9,12-X2-o-carboranes, 9-X-12-X'-o-carboranes, 9-X-m-carboranes, 9,10-X2-m-carboranes, and 9-X-10-X'-m-carboranes (X, X' = Cl, Br, I) has been developed on the basis of our previous work. The success of this transformation relies on the usage of trifluoromethanesulfonic acid (HOTf), the easily available strong Brønsted acid. The addition of HOTf greatly increases the electrophilicity of N-haloamides through hydrogen bonding interaction, resulting in the low loading of N-haloamides, short reaction time, and mild reaction conditions. Additionally, the solvent 1,1,1,3,3,3-hexafluoro-2-propanol (HFIP) is also essential to further increase the acidity of HOTf.
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Affiliation(s)
- Wen Lu
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Yanxuan Wu
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Yan-Na Ma
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Feijing Chen
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Xuenian Chen
- Green Catalysis Center, College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
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8
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Yue F, Ma H, Song H, Liu Y, Dong J, Wang Q. Alkylboronic acids as alkylating agents: photoredox-catalyzed alkylation reactions assisted by K 3PO 4. Chem Sci 2022; 13:13466-13474. [PMID: 36507180 PMCID: PMC9683010 DOI: 10.1039/d2sc05521j] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/05/2022] [Accepted: 10/31/2022] [Indexed: 11/09/2022] Open
Abstract
Despite the ubiquity of alkylboronic acids in organic synthesis, their utility as alkyl radical precursors in visible-light-induced photocatalytic reactions is limited by their high oxidation potentials. In this study, we demonstrated that an inorganophosphorus compound can modulate the oxidation potentials of alkylboronic acids so that they can act as alkyl radical precursors. We propose a mechanism based on the results of fluorescence quenching experiments, electrochemical experiments, 11B and 31P NMR spectroscopy, and other techniques. In addition, we describe a simple and reliable alkylation method that has good functional group tolerance and can be used for direct C-B chlorination, cyanation, vinylation, alkynylation, and allylation, as well as late-stage functionalization of derivatized drug molecules. Notably, alkylboronic acids can be selectively activated in the presence of a boronic pinacol ester.
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Affiliation(s)
- Fuyang Yue
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai UniversityTianjin 300071People's Republic of China
| | - Henan Ma
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai UniversityTianjin 300071People's Republic of China
| | - Hongjian Song
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai UniversityTianjin 300071People's Republic of China
| | - Yuxiu Liu
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai UniversityTianjin 300071People's Republic of China
| | - Jianyang Dong
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai UniversityTianjin 300071People's Republic of China
| | - Qingmin Wang
- State Key Laboratory of Elemento-Organic Chemistry, Research Institute of Elemento-Organic Chemistry, College of Chemistry, Frontiers Science Center for New Organic Matter, Nankai UniversityTianjin 300071People's Republic of China
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9
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Li S, Zhang J, Xie Z. Visible-Light-Induced Palladium-Catalyzed Cross-Coupling of Iodocarboranes with (Hetero)Arenes. Org Lett 2022; 24:7497-7501. [PMID: 36201284 DOI: 10.1021/acs.orglett.2c02648] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
This work describes a general method for the efficient production of a class of cage B-centered carboranyl radicals at the B3, B4, and B9 sites via a visible-light-promoted palladium(0)/palladium(I) pathway using readily available iodo-o-carboranes as the starting materials. The electrophilicities of these hypervalent boron-centered radicals decrease in the following order: B3 > B4 > B9. They are useful intermediates for the preparation of a family of cage B-(hetero)arylated o-carboranes at ambient temperature.
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Affiliation(s)
- Shimeng Li
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Jie Zhang
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
| | - Zuowei Xie
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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10
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Zhang LB, Xie Z. Iridium-Catalyzed Selective B(4)-H Amination of o-Carboranes with Anthranils. Org Lett 2022; 24:7077-7081. [PMID: 36148973 DOI: 10.1021/acs.orglett.2c02590] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/29/2022]
Abstract
We report here a catalytic selective cage B4-H amination of o-carboranes employing an Ir(III) complex as a catalyst and anthranils as aminating agents, leading to a large class of B4-aminated o-carboranes with very high yields and a broad substrate scope under mild conditions without any oxidants. In these reactions, the carboxyl group serves as a traceless directing unit to determine the site selectivity and degree of substitution.
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Affiliation(s)
- Lin-Bao Zhang
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China.,State Key Laboratory Base of Eco-Chemical Engineering, College of Chemistry and Molecular Engineering, Qingdao University of Science & Technology, Qingdao 266042, China
| | - Zuowei Xie
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, New Territories, Hong Kong, China
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11
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Anderson KP, Djurovich PI, Rubio VP, Liang A, Spokoyny AM. Metal-Catalyzed and Metal-Free Nucleophilic Substitution of 7-I-B 18H 21. Inorg Chem 2022; 61:15051-15057. [PMID: 36098984 DOI: 10.1021/acs.inorgchem.2c02116] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/28/2022]
Abstract
In this work, two pathways of reactivity are investigated to generate site-specific substitutions at the B7 vertex of the luminescent boron cluster, anti-B18H22. First, a palladium-catalyzed cross-coupling reaction utilizing the precursor 7-I-B18H21 and a series of model nucleophiles was developed, ultimately producing several B-N- and B-O-substituted species. Interestingly, the B-I bond in this cluster can also be substituted in an uncatalyzed fashion, leading to the formation of various B-N, B-O, and B-S products. This work highlights intricate differences corresponding to these two reaction pathways and analyzes the role of solvents and additives on product distributions. As a result of our synthetic studies, seven new B18-based clusters were synthesized, isolated, and characterized by mass spectrometry and nuclear magnetic resonance (NMR) spectroscopy. The photoluminescence properties of two structurally similar ether and thioether products were further investigated, with both exhibiting blue fluorescence in solution at 298 K and long-lived green or yellow phosphorescence at 77 K. Overall, this work shows, for the first time, the ability to perform substitution of a boron-halogen bond with nucleophiles in a B18-based cluster, resulting in the formation of photoluminescent molecules.
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Affiliation(s)
- Kierstyn P Anderson
- Department of Chemistry and Biochemistry and California NanoSystem Institute (CNSI), University of California, Los Angeles, California 90095, United States
| | - Peter I Djurovich
- Department of Chemistry, University of Southern California, Los Angeles, California 90089, United States
| | - Victoria P Rubio
- Department of Chemistry and Biochemistry and California NanoSystem Institute (CNSI), University of California, Los Angeles, California 90095, United States
| | - Aimee Liang
- Department of Chemistry and Biochemistry and California NanoSystem Institute (CNSI), University of California, Los Angeles, California 90095, United States
| | - Alexander M Spokoyny
- Department of Chemistry and Biochemistry and California NanoSystem Institute (CNSI), University of California, Los Angeles, California 90095, United States
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12
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Chen M, Xu J, Zhao D, Sun F, Tian S, Tu D, Lu C, Yan H. Site-Selective Functionalization of Carboranes at the Electron-Rich Boron Vertex: Photocatalytic B-C Coupling via a Carboranyl Cage Radical. Angew Chem Int Ed Engl 2022; 61:e202205672. [PMID: 35670361 DOI: 10.1002/anie.202205672] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/18/2022] [Indexed: 12/14/2022]
Abstract
Functionalization of carboranes in a vertex-specific manner is a perennial challenge. Here, we report a photocatalytic B-C coupling for the selective functionalization of carboranes at the boron site which is most distal to carbon. This reaction was achieved by the photo-induced decarboxylation of carborane carboxylic acids to generate boron vertex-centered carboranyl radicals. Theoretical calculations also demonstrate that the reaction more easily occurs at the boron site bearing higher electron density owing to the lower energy barrier for a single-electron transfer to generate a carboranyl radical. By using this strategy, a number of functionalized carboranes could be accessed through alkylation, alkenylation, and heteroarylation under mild conditions. Moreover, both a highly efficient blue emitter with a solid-state luminous efficiency of 42 % and a drug candidate for boron neutron capture therapy (BNCT) containing targeting and fluorine units were obtained.
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Affiliation(s)
- Meng Chen
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Jingkai Xu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Deshi Zhao
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Fangxiang Sun
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Songlin Tian
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Deshuang Tu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Changsheng Lu
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
| | - Hong Yan
- State Key Laboratory of Coordination Chemistry, Jiangsu Key Laboratory of Advanced Organic Materials, School of Chemistry and Chemical Engineering, Nanjing University, Nanjing, 210023, China
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13
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Zhou P, Chen Y, Xie Z. Iron-Catalyzed Selective B–H Activation for 4/5-fold Methylation and Arylation of Carboranes. ACS Catal 2022. [DOI: 10.1021/acscatal.2c02120] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/04/2023]
Affiliation(s)
- Peng Zhou
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China
| | - Yu Chen
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China
| | - Zuowei Xie
- Department of Chemistry and State Key Laboratory of Synthetic Chemistry, The Chinese University of Hong Kong, Shatin, N. T., Hong Kong, China
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14
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Chen M, Xu J, Zhao D, Sun F, Tian S, Tu D, Lu C, Yan H. Site‐Selective Functionalization of Carboranes at Electron‐Rich Boron Vertex: Photocatalytic B‐C Coupling via a Carboranyl Cage Radical. Angew Chem Int Ed Engl 2022. [DOI: 10.1002/ange.202205672] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/09/2022]
Affiliation(s)
- Meng Chen
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Jingkai Xu
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Deshi Zhao
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Fangxiang Sun
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Songlin Tian
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Deshuang Tu
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Changsheng Lu
- Nanjing University School of Chemistry and Chemical Engineering CHINA
| | - Hong Yan
- Nanjing University School of Chemistry and Chemical Engineering 22 Hankou Rd. 210093 Nanjing CHINA
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15
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Wang Y, Gao Y, Guo W, Zhao Q, Ma YN, Chen X. Highly selective electrophilic B(9)-amination of o-carborane driven by HOTf and HFIP. Org Chem Front 2022. [DOI: 10.1039/d2qo00732k] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.5] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
Abstract
An efficient B(9) electrophilic amination of o-carboranes with azodicarboxylates, promoted by a Brønsted acid and HFIP, was developed.
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Affiliation(s)
- Yan Wang
- School of Chemistry and Chemical Engineering, Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, Henan Normal University, Xinxiang, Henan 453007, China
| | - Yan Gao
- School of Chemistry and Chemical Engineering, Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, Henan Normal University, Xinxiang, Henan 453007, China
| | - Wenjing Guo
- College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Qianyi Zhao
- School of Chemistry and Chemical Engineering, Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, Henan Normal University, Xinxiang, Henan 453007, China
| | - Yan-Na Ma
- College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
| | - Xuenian Chen
- School of Chemistry and Chemical Engineering, Henan Key Laboratory of Boron Chemistry and Advanced Energy Materials, Henan Normal University, Xinxiang, Henan 453007, China
- College of Chemistry, Zhengzhou University, Zhengzhou, Henan 450001, China
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