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Samanta A, Behera P, Chaubey A, Mondal A, Pal D, Mohar K, Roy L, Srimani D. Experimental and theoretical insights for designing Zn 2+ complexes to trigger chemo-selective hetero-coupling of alcohols. Chem Commun (Camb) 2024; 60:4056-4059. [PMID: 38505958 DOI: 10.1039/d4cc00864b] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 03/21/2024]
Abstract
Designing well-defined Zn-complexes for sustainable dehydrogenative catalysis overcoming the difficulties associated with activating Zn2+(d10)-metal species is considered paramount goal in catalysis. Herein, we explore the plausibility of β-alkylation of secondary alcohols with primary alcohols by well-defined 3d10 Zn-complexes. Detailed organometallic and catalytic investigations, in conjunction with computational analyses, were conducted to ascertain the potential involvement of the catalyst at various stages of the catalytic process.
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Affiliation(s)
- Arup Samanta
- Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India.
| | - Prativa Behera
- Institute of Chemical Technology Mumbai, IOC Odisha Campus Bhubaneswar, Bhubaneswar, Odisha 751013, India.
| | - Amit Chaubey
- Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India.
| | - Avijit Mondal
- Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India.
| | - Debjyoti Pal
- Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India.
| | - Kailash Mohar
- Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India.
| | - Lisa Roy
- Institute of Chemical Technology Mumbai, IOC Odisha Campus Bhubaneswar, Bhubaneswar, Odisha 751013, India.
| | - Dipankar Srimani
- Department of Chemistry, Indian Institute of Technology-Guwahati, Kamrup, Assam 781039, India.
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Mallick S, Mandal T, Kumari N, Roy L, De Sarkar S. Divergent Electrochemical Synthesis of Indoles through pK a Regulation of Amides: Synthetic and Mechanistic Insights. Chemistry 2024; 30:e202304002. [PMID: 38290995 DOI: 10.1002/chem.202304002] [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: 11/30/2023] [Revised: 01/15/2024] [Accepted: 01/30/2024] [Indexed: 02/01/2024]
Abstract
A divergent synthetic approach to access highly substituted indole scaffolds is illustrated. By virtue of a tunable electrochemical strategy, distinct control over the C-3 substitution pattern was achieved by employing two analogous 2-styrylaniline precursors. The chemoselectivity is governed by the fine-tuning of the acidity of the amide proton, relying on the appropriate selection of N-protecting groups, and assisted by the reactivity of the electrogenerated intermediates. Detailed mechanistic investigations based on cyclic voltametric experiments and computational studies revealed the crucial role of water additive, which assists the proton-coupled electron transfer event for highly acidic amide precursors, followed by an energetically favorable intramolecular C-N coupling, causing exclusive fabrication of the C-3 unsubstituted indoles. Alternatively, the implementation of an electrogenerated cationic olefin activator delivers the C-3 substituted indoles through the preferential nucleophilic nature of the N-acyl amides. This electrochemical approach of judicious selection of N-protecting groups to regulate pKa/E° provides an expansion in the domain of switchable generation of heterocyclic derivatives in a sustainable fashion, with high regio- and chemoselectivity.
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Affiliation(s)
- Samrat Mallick
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Tanumoy Mandal
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Nidhi Kumari
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
| | - Lisa Roy
- Institute of Chemical Technology Mumbai-IOC Odisha Campus, Bhubaneswar, Bhubaneswar, 751013, India
| | - Suman De Sarkar
- Department of Chemical Sciences, Indian Institute of Science Education and Research Kolkata, Mohanpur, 741246, India
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3
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Singh A, Roy L. Evolution in the Design of Water Oxidation Catalysts with Transition-Metals: A Perspective on Biological, Molecular, Supramolecular, and Hybrid Approaches. ACS OMEGA 2024; 9:9886-9920. [PMID: 38463281 PMCID: PMC10918817 DOI: 10.1021/acsomega.3c07847] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Subscribe] [Scholar Register] [Received: 10/08/2023] [Revised: 02/05/2024] [Accepted: 02/07/2024] [Indexed: 03/12/2024]
Abstract
Increased demand for a carbon-neutral sustainable energy scheme augmented by climatic threats motivates the design and exploration of novel approaches that reserve intermittent solar energy in the form of chemical bonds in molecules and materials. In this context, inspired by biological processes, artificial photosynthesis has garnered significant attention as a promising solution to convert solar power into chemical fuels from abundantly found H2O. Among the two redox half-reactions in artificial photosynthesis, the four-electron oxidation of water according to 2H2O → O2 + 4H+ + 4e- comprises the major bottleneck and is a severe impediment toward sustainable energy production. As such, devising new catalytic platforms, with traditional concepts of molecular, materials and biological catalysis and capable of integrating the functional architectures of the natural oxygen-evolving complex in photosystem II would certainly be a value-addition toward this objective. In this review, we discuss the progress in construction of ideal water oxidation catalysts (WOCs), starting with the ingenuity of the biological design with earth-abundant transition metal ions, which then diverges into molecular, supramolecular and hybrid approaches, blurring any existing chemical or conceptual boundaries. We focus on the geometric, electronic, and mechanistic understanding of state-of-the-art homogeneous transition-metal containing molecular WOCs and summarize the limiting factors such as choice of ligands and predominance of environmentally unrewarding and expensive noble-metals, necessity of high-valency on metal, thermodynamic instability of intermediates, and reversibility of reactions that create challenges in construction of robust and efficient water oxidation catalyst. We highlight how judicious heterogenization of atom-efficient molecular WOCs in supramolecular and hybrid approaches put forth promising avenues to alleviate the existing problems in molecular catalysis, albeit retaining their fascinating intrinsic reactivities. Taken together, our overview is expected to provide guiding principles on opportunities, challenges, and crucial factors for designing novel water oxidation catalysts based on a synergy between conventional and contemporary methodologies that will incite the expansion of the domain of artificial photosynthesis.
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Affiliation(s)
- Ajeet
Kumar Singh
- Institute of Chemical Technology
Mumbai−IOC Odisha Campus Bhubaneswar, IIT Kharagpur Extension
Centre, Bhubaneswar − 751013 India
| | - Lisa Roy
- Institute of Chemical Technology
Mumbai−IOC Odisha Campus Bhubaneswar, IIT Kharagpur Extension
Centre, Bhubaneswar − 751013 India
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Choukairi Afailal N, Borrell M, Cianfanelli M, Costas M. Dearomative syn-Dihydroxylation of Naphthalenes with a Biomimetic Iron Catalyst. J Am Chem Soc 2024; 146:240-249. [PMID: 38123164 PMCID: PMC10785824 DOI: 10.1021/jacs.3c08565] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/07/2023] [Revised: 11/15/2023] [Accepted: 12/04/2023] [Indexed: 12/23/2023]
Abstract
Arenes are interesting feedstocks for organic synthesis because of their natural abundance. However, the stability conferred by aromaticity severely limits their reactivity, mostly to reactions where aromaticity is retained. Methods for oxidative dearomatization of unactivated arenes are exceedingly rare but particularly valuable because the introduction of Csp3-O bonds transforms the flat aromatic ring in 3D skeletons and confers the oxygenated molecules with a very rich chemistry suitable for diversification. Mimicking the activity of naphthalene dioxygenase (NDO), a non-heme iron-dependent bacterial enzyme, herein we describe the catalytic syn-dihydroxylation of naphthalenes with hydrogen peroxide, employing a sterically encumbered and exceedingly reactive yet chemoselective iron catalyst. The high electrophilicity of hypervalent iron oxo species is devised as a key to enabling overcoming the aromatically promoted kinetic stability. Interestingly, the first dihydroxylation of the arene renders a reactive olefinic site ready for further dihydroxylation. Sequential bis-dihydroxylation of a broad range of naphthalenes provides valuable tetrahydroxylated products in preparative yields, amenable for rapid diversification.
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Affiliation(s)
- Najoua Choukairi Afailal
- Institut de Química
Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Girona E-17071, Catalonia, Spain
| | - Margarida Borrell
- Institut de Química
Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Girona E-17071, Catalonia, Spain
| | - Marco Cianfanelli
- Institut de Química
Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Girona E-17071, Catalonia, Spain
| | - Miquel Costas
- Institut de Química
Computacional i Catàlisi (IQCC) and Departament de Química, Universitat de Girona, Campus Montilivi, Girona E-17071, Catalonia, Spain
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Biologically inspired nonheme iron complex-catalyzed cis-dihydroxylation of alkenes modeling Rieske dioxygenases. Coord Chem Rev 2023. [DOI: 10.1016/j.ccr.2022.214945] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/27/2022]
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Chakraborty S, Mondal R, Pal S, Guin AK, Roy L, Paul ND. Zn(II)-Catalyzed Selective N-Alkylation of Amines with Alcohols Using Redox Noninnocent Azo-Aromatic Ligand as Electron and Hydrogen Reservoir. J Org Chem 2023; 88:771-787. [PMID: 36577023 DOI: 10.1021/acs.joc.2c01773] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/29/2022]
Abstract
We report a sustainable and eco-friendly approach for selective N-alkylation of various amines by alcohols, catalyzed by a well-defined Zn(II)-catalyst, Zn(La)Cl2 (1a), bearing a tridentate arylazo scaffold. A total of 57 N-alkylated amines were prepared in good to excellent yields, out of which 17 examples are new. The Zn(II)-catalyst shows wide functional group tolerance, is compatible with the synthesis of dialkylated amines via double N-alkylation of diamines, and produces the precursors in high yields for the marketed drugs tripelennamine and thonzonium bromide in gram-scale reactions. Control reactions and DFT studies indicate that electron transfer events occur at the azo-chromophore throughout the catalytic process, which shuttles between neutral azo, one-electron reduced azo-anion radical, and two-electron reduced hydrazo forms acting both as electron and hydrogen reservoir, enabling the Zn(II)-catalyst for N-alkylation reaction.
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Affiliation(s)
- Subhajit Chakraborty
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Botanic Garden, Howrah 711103, India
| | - Rakesh Mondal
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Botanic Garden, Howrah 711103, India
| | - Subhasree Pal
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Botanic Garden, Howrah 711103, India
| | - Amit Kumar Guin
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Botanic Garden, Howrah 711103, India
| | - Lisa Roy
- Institute of Chemical Technology Mumbai - IOC Odisha Campus Bhubaneswar, Bhubaneswar 751013, India
| | - Nanda D Paul
- Department of Chemistry, Indian Institute of Engineering Science and Technology, Shibpur, Botanic Garden, Howrah 711103, India
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Roy L. Theoretical Identification of the Factors Governing the Reactivity of C-H Bond Activation by Non-Heme Iron(IV)-Oxo Complexes. Chempluschem 2020; 84:893-906. [PMID: 31943994 DOI: 10.1002/cplu.201900178] [Citation(s) in RCA: 11] [Impact Index Per Article: 2.8] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 03/19/2019] [Revised: 05/30/2019] [Indexed: 11/06/2022]
Abstract
Selective functionalization of C-H bonds provides a straightforward approach to a large variety of well-defined derivatives. High-valent mononuclear iron(IV)-oxo complexes are proposed to carry out these C-H activation reactions in enzymes or in biomimetic syntheses. In this Minireview, we aim to highlight the features that delineate the distinct reactivity of non-heme oxo-iron(IV) motifs to cleave strong C-H bonds in hydrocarbons, primarily focusing on the hydrogen atom transfer (HAT) process. We describe how the structural and electronic properties of supporting ligands modulate the oxidative property of the iron(IV)-oxo complexes. Furthermore, we highlight the decisive role played by spin-state in these biomimetic reactions. We also discuss how tunneling and external perturbations like electric field influence the transfer of hydrogen atoms. Lastly, we emphasize how computations could work as a practical guide to sketch and develop synthetic models with greater efficacy.
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Affiliation(s)
- Lisa Roy
- Institute of Chemical Technology Mumbai IOC Odisha Campus Bhubaneswar, IIT Kharagpur Extension Centre, Bhubaneswar, 751013, Odisha, India
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Characterized cis-Fe V(O)(OH) intermediate mimics enzymatic oxidations in the gas phase. Nat Commun 2019; 10:901. [PMID: 30796210 PMCID: PMC6385299 DOI: 10.1038/s41467-019-08668-2] [Citation(s) in RCA: 39] [Impact Index Per Article: 7.8] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/19/2018] [Accepted: 01/16/2019] [Indexed: 02/04/2023] Open
Abstract
FeV(O)(OH) species have long been proposed to play a key role in a wide range of biomimetic and enzymatic oxidations, including as intermediates in arene dihydroxylation catalyzed by Rieske oxygenases. However, the inability to accumulate these intermediates in solution has thus far prevented their spectroscopic and chemical characterization. Thus, we use gas-phase ion spectroscopy and reactivity analysis to characterize the highly reactive [FeV(O)(OH)(5tips3tpa)]2+ (32+) complex. The results show that 32+ hydroxylates C–H bonds via a rebound mechanism involving two different ligands at the Fe center and dihydroxylates olefins and arenes. Hence, this study provides a direct evidence of FeV(O)(OH) species in non-heme iron catalysis. Furthermore, the reactivity of 32+ accounts for the unique behavior of Rieske oxygenases. The use of gas-phase ion characterization allows us to address issues related to highly reactive intermediates that other methods are unable to solve in the context of catalysis and enzymology. FeV(O)(OH) species have long been thought to play a role in a range of enzymatic oxidations, but their characterization has remained elusive. Here, using gas-phase ion spectroscopy, the authors characterize an FeV(O)(OH) species and find that its reactivity mimics that of Rieske oxygenases.
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