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Li P, Tu JL, Hu AM, Zhu Y, Yin J, Guo L, Yang C, Xia W. Iron-Catalyzed Multicomponent C-H Alkylation of in Situ Generated Imines via Photoinduced Ligand-to-Metal Charge Transfer. Org Lett 2024; 26:6347-6352. [PMID: 39038192 DOI: 10.1021/acs.orglett.4c01986] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/24/2024]
Abstract
Herein, we describe a novel photoinduced iron-catalyzed strategy for multicomponent C-H alkylation of in situ generated imines. By utilizing the alkyl radicals generated through iron-mediated photocatalytic C-H activation, the imines formed in situ are further subjected to addition reactions, resulting in the synthesis of various secondary and tertiary amine products. This method is simple to operate and does not require additional oxidants. It is applicable to inert alkane substrates such as cyclic alkanes, cyclic ethers, toluene, and ketones. The reaction is also compatible with various aromatic amines, alkyl amines, halogenated aromatic amines, as well as aromatic aldehydes, alkyl aldehydes, and cinnamaldehyde, among other different types of aldehydes.
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Affiliation(s)
- Pengcheng Li
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Jia-Lin Tu
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Ao-Men Hu
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Yining Zhu
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Jiawen Yin
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Lin Guo
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Chao Yang
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
| | - Wujiong Xia
- State Key Lab of Urban Water Resource and Environment, School of Science, Harbin Institute of Technology (Shenzhen), Shenzhen 518055, China
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
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Mahato J, Bera PS, Saha TK. Synthesis of imines from the coupling reaction of alcohols and amines catalyzed by phosphine-free cobalt(II) complexes. Org Biomol Chem 2024; 22:4528-4535. [PMID: 38752768 DOI: 10.1039/d4ob00351a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 06/06/2024]
Abstract
Phosphine-free, air stable cobalt(II) based complexes (1a and 1b) consisting of ligands L1H2 and L2H2 (L1H2 = N,N'-((1,2-phenylenebis(azaneylylidene))bis(methaneylylidene))diphenol and L2H2 = N,N'-bis(4-diethylaminosalicylidene)-4,5-dichloro-1,2-phenylenediamine) were synthesized and utilized as catalysts in the coupling reaction of alcohols with amines into imines following an acceptorless dehydrogenative pathway. The reactions were carried out in the presence of t-BuOK base with low catalyst loading (1 mol%) in an open atmosphere. The corresponding imines were isolated in moderate to excellent yields. The methodology was screened with different substituted alcohols and amines. The proposed mechanistic pathway of this reaction was ascertained through intermediate mass and 1H NMR analyses. Most of the previously reported 3d transition metal catalysts used in imine synthesis reactions have a phosphine ligand environment, and the reactions were performed under inert conditions. Herein we have developed a sustainable route for the synthesis of imines from the coupling reaction of alcohols with amines under aerial reaction conditions using phosphine-free air stable cobalt catalysts.
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Affiliation(s)
- Jharna Mahato
- Department of Chemistry, National Institute of Technology Durgapur, West Bengal, 713209, India.
| | - Partha Sarathi Bera
- Department of Chemistry, National Institute of Technology Durgapur, West Bengal, 713209, India.
| | - Tanmoy Kumar Saha
- Department of Chemistry, National Institute of Technology Durgapur, West Bengal, 713209, India.
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Cattani S, Cera G. Modern Organometallic C-H Functionalizations with Earth-Abundant Iron Catalysts: An Update. Chem Asian J 2024; 19:e202300897. [PMID: 38051920 DOI: 10.1002/asia.202300897] [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: 10/11/2023] [Revised: 11/13/2023] [Indexed: 12/07/2023]
Abstract
Iron-catalyzed C-H activation has recently emerged as an increasingly powerful synthetic method for the step- and atom- economical direct C-H functionalizations of otherwise inert C-H bonds. Iron's low-cost and toxicity along with its catalytic versatility have encouraged the scientific community to elect this metal for the development of new C-H activation methodologies. Within this review, we aim to present a collection of the most recent examples of iron-catalyzed C-H functionalizations with a particular emphasis on modern synthetic strategies and mechanistic aspects.
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Affiliation(s)
- Silvia Cattani
- Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma, Parco Area delle Scienze 17/A, 43124, Parma, Italy
| | - Gianpiero Cera
- Dipartimento di Scienze Chimiche, della Vita e della Sostenibilità Ambientale, Università di Parma, Parco Area delle Scienze 17/A, 43124, Parma, Italy
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Yang J, Tripodi GL, Derks MTGM, Seo MS, Lee YM, Southwell KW, Shearer J, Roithová J, Nam W. Generation, Spectroscopic Characterization, and Computational Analysis of a Six-Coordinate Cobalt(III)-Imidyl Complex with an Unusual S = 3/2 Ground State that Promotes N-Group and Hydrogen Atom-Transfer Reactions with Exogenous Substrates. J Am Chem Soc 2023; 145:26106-26121. [PMID: 37997643 PMCID: PMC11175169 DOI: 10.1021/jacs.3c08117] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/25/2023]
Abstract
We report the synthesis and characterization of a mononuclear nonheme cobalt(III)-imidyl complex, [Co(NTs)(TQA)(OTf)]+ (1), with an S = 3/2 spin state that is capable of facilitating exogenous substrate modifications. Complex 1 was generated from the reaction of CoII(TQA)(OTf)2 with PhINTs at -20 °C. A flow setup with ESI-MS detection was used to explore the kinetics of the formation, stability, and degradation pathway of 1 in solution by treating the Co(II) precursor with PhINTs. Co K-edge XAS data revealed a distinct shift in the Co K-edge compared to the Co(II) precursor, in agreement with the formation of a Co(III) intermediate. The unusual S = 3/2 spin state was proposed based on EPR, DFT, and CASSCF calculations and Co Kβ XES results. Co K-edge XAS and IR photodissociation (IRPD) spectroscopies demonstrate that 1 is a six-coordinate species, and IRPD and resonance Raman spectroscopies are consistent with 1 being exclusively the isomer with the NT ligand occupying the vacant site trans to the TQA aliphatic amine nitrogen atom. Electronic structure calculations (broken symmetry DFT and CASSCF/NEVPT2) demonstrate an S = 3/2 oxidation state resulting from the strong antiferromagnetic coupling of an •NTs spin to the high-spin S = 2 Co(III) center. Reactivity studies of 1 with PPh3 derivatives revealed its electrophilic characteristic in the nitrene-transfer reaction. While the activation of C-H bonds by 1 was proved to be kinetically challenging, 1 could oxidize weak O-H and N-H bonds. Complex 1 is, therefore, a rare example of a Co(III)-imidyl complex capable of exogenous substrate transformations.
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Affiliation(s)
- Jindou Yang
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Guilherme L. Tripodi
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Max T. G. M. Derks
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Mi Sook Seo
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Yong-Min Lee
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
| | - Kendal W. Southwell
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jason Shearer
- Department of Chemistry, Trinity University, San Antonio, Texas 78212, United States
| | - Jana Roithová
- Institute for Molecules and Materials, Radboud University, Heyendaalseweg 135, 6525 AJ Nijmegen, The Netherlands
| | - Wonwoo Nam
- Department of Chemistry and Nano Science, Ewha Womans University, Seoul 03760, Korea
- State Key Laboratory for Oxo Synthesis and Selective Oxidation, Lanzhou Institute of Chemical Physics, Chinese Academy of Sciences, Lanzhou 730000, China
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Rana T, Ghosh A, Aher YN, Pawar AB. Harnessing Vinyl Acetate as an Acetylene Equivalent in Redox-Neutral Cp*Co(III)-Catalyzed C-H Activation/Annulation for the Synthesis of Isoquinolones and Pyridones. ACS OMEGA 2023; 8:25262-25271. [PMID: 37483194 PMCID: PMC10357576 DOI: 10.1021/acsomega.3c02352] [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: 04/07/2023] [Accepted: 06/23/2023] [Indexed: 07/25/2023]
Abstract
We have developed Cp*Co(III)-catalyzed redox-neutral synthesis of 3,4-unsubstituted isoquinoline 1(2H)-ones at ambient temperature using N-chloroamides as a starting material. The reaction utilizes vinyl acetate as an inexpensive and benign acetylene surrogate. The N-Cl bond of the N-chlorobenzamides plays the role of an internal oxidant and hence precludes the need for an external oxidant. The reaction works with a wide range of substrates having various functional groups and a substrate containing a heterocyclic ring. Notably, the reaction is extended to the N-chloroacrylamides in which vinylic C-H activation occurs to furnish the 2-pyridone derivatives. Preliminary mechanistic studies were also conducted to shed light on the mechanism of this reaction.
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Bhaduri N, Pawar AB. Redox-neutral C-H annulation strategies for the synthesis of heterocycles via high-valent Cp*Co(III) catalysis. Org Biomol Chem 2023; 21:3918-3941. [PMID: 37128760 DOI: 10.1039/d3ob00133d] [Citation(s) in RCA: 4] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/03/2023]
Abstract
A variety of biologically active molecules, pharmaceuticals, and natural products consist of a nitrogen-containing heterocyclic backbone. The majority of them are isoquinolones, indoles, isoquinolines, etc.; thereby the synthesis and derivatization of such heterocycles are synthetically very relevant. Also, certain naphthol derivatives have high synthetic utility as agrochemicals and in dye industries. Previous approaches have utilized ruthenium, rhodium, or iridium which may not be desirable due to the high toxicity, low abundance, and high cost of such 4d and 5d metals. Moreover, the need for an external oxidant during the reaction also adds by-products to the system. A high-valent cobalt-catalyzed redox-neutral C-H functionalization strategy has emerged to be a far better alternative in this regard. The use of the non-noble metal cobalt allows for selectivity and specificity in product formation. Also, the redox-neutral concept avoids the use of an external oxidant either due to the presence of a metal in a non-variable oxidation state throughout the catalytic cycle or due to the presence of an oxidizing directing group or an oxidizing coupling partner. Such an oxidizing directing group not only directs the catalyst to a specific reaction site by chelation but also regenerates the catalyst at the end of the cycle. Certain bonds such as N-O, N-N, N-Cl, N-S, and C-S are the main game-players behind the oxidizing property of such directing groups. In the other case, the directing group only chelates the catalyst to a reaction center, whereas the oxidation is carried out by the upcoming group/coupling partner. Overall, merging the redox-neutral concept with the high-valent cobalt catalysis is paving the way forward toward a sustainable and environmentally friendly approach. This review critically describes the mechanistic understanding, scope, limitations, and synthesis of various biologically relevant heterocycles via the redox-neutral concept in the high-valent Cp*Co(III)-catalyzed C-H functionalization chemistry domain.
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Affiliation(s)
- Nilanjan Bhaduri
- 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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