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Guria S, Hassan MMM, Dey S, Singh KN, Chattopadhyay B. Sterically Controlled Lewis Acid-Base Interaction Toward para-Selective Borylation of Aromatic Aldimines and Benzylamines. Angew Chem Int Ed Engl 2024; 63:e202409010. [PMID: 39012678 DOI: 10.1002/anie.202409010] [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: 05/13/2024] [Revised: 07/15/2024] [Accepted: 07/16/2024] [Indexed: 07/17/2024]
Abstract
Site-selective C-H bond functionalization of arenes at the para position remains extremely challenging primarily due to its relative inaccessibility from the catalytic site. As a consequence, it is significantly restricted to limited molecular scaffolds. Herein, we report a method for the para-C-H borylation of aromatic aldimines and benzylamines using commercially available ligands under iridium catalysis. The established method displays excellent para selectivity for variously substituted aromatic aldimines, benzylamines and bioactive molecules. Based on several control experiments, it is proposed that a Lewis acid-base interaction between the nitrogen and boron functionality guides the para selectivity via a steric shield for the aromatic aldimines, where Bpin acts as a transient directing group. However, the steric shield of the in situ generated N-Bpin moiety controlled the overall selectivity for the para borylation of benzylamines.
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Affiliation(s)
- Saikat Guria
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, 226014, Uttar Pradesh, India
| | - Mirja Md Mahamudul Hassan
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, 226014, Uttar Pradesh, India
| | - Sayan Dey
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, 226014, Uttar Pradesh, India
| | - Krishna Nand Singh
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi, 221005, India
| | - Buddhadeb Chattopadhyay
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow, 226014, Uttar Pradesh, India
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Trouvé J, Delahaye V, Tomasini M, Rajeshwaran P, Roisnel T, Poater A, Gramage-Doria R. Repurposing a supramolecular iridium catalyst via secondary Zn⋯O[double bond, length as m-dash]C weak interactions between the ligand and substrate leads to ortho-selective C(sp 2)-H borylation of benzamides with unusual kinetics. Chem Sci 2024; 15:11794-11806. [PMID: 39092112 PMCID: PMC11290415 DOI: 10.1039/d4sc01515k] [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: 03/05/2024] [Accepted: 06/10/2024] [Indexed: 08/04/2024] Open
Abstract
The iridium-catalyzed C-H borylation of benzamides typically leads to meta and para selectivities using state-of-the-art iridium-based N,N-chelating bipyridine ligands. However, reaching ortho selectivity patterns requires extensive trial-and-error screening via molecular design at the ligand first coordination sphere. Herein, we demonstrate that triazolylpyridines are excellent ligands for the selective iridium-catalyzed ortho C-H borylation of tertiary benzamides and, importantly, we demonstrate the almost negligible effect of the first coordination sphere in the selectivity, which is so far unprecedented in iridium C-H bond borylations. Remarkably, the activity is dramatically enhanced by exploiting a remote Zn⋯O[double bond, length as m-dash]C weak interaction between the substrate and a rationally designed molecular-recognition site in the catalyst. Kinetic studies and DFT calculations indicate that the iridium-catalyzed C-H activation step is not rate-determining, this being unique for remotely controlled C-H functionalizations. Consequently, a previously established supramolecular iridium catalyst designed for meta-borylation of pyridines is now compatible with the ortho-borylation of benzamides, a regioselectivity switch that is counter-intuitive regarding precedents in the literature. In addition, we highlight the role of the cyclohexene additive in avoiding the formation of undesired side-products as well as accelerating the HBpin release event that precedes the catalyst regeneration step, which is highly relevant for the design of powerful and selective iridium borylating catalysts.
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Affiliation(s)
| | | | - Michele Tomasini
- Departament de Química, Institut de Química Computacional i Catàlisi, Universitat de Girona c/Maria Aurèlia Capmany 69 17003 Girona Catalonia Spain
| | | | | | - Albert Poater
- Departament de Química, Institut de Química Computacional i Catàlisi, Universitat de Girona c/Maria Aurèlia Capmany 69 17003 Girona Catalonia Spain
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King RP, Yang JY. Modular preparation of cationic bipyridines and azaarenes via C-H activation. Chem Sci 2023; 14:13530-13536. [PMID: 38033896 PMCID: PMC10686024 DOI: 10.1039/d3sc04864k] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 09/14/2023] [Accepted: 11/05/2023] [Indexed: 12/02/2023] Open
Abstract
Bipyridines are ubiquitous in organic and inorganic chemistry because of their redox and photochemical properties and their utility as ligands to transition metals. Cationic substituents on bipyridines and azaarenes are valuable as powerful electron-withdrawing functionalities that also enhance solubility in polar solvents, but there are no general methods for direct functionalization. A versatile method for the preparation of trimethylammonium- and triarylphosphonium-substituted bipyridines and azaheterocycles is disclosed. This methodology showcases a C-H activation of pyridine N-oxides that enables a highly modular and scalable synthesis of a diverse array of cationically charged azaarenes. The addition of trimethylammonium functionalities on bipyridine derivatives resulted in more anodic reduction potentials (up to 700 mV) and increased electrochemical reversibility compared to the neutral unfunctionalized bipyridine. Additonally, metallation of 4-triphenylphosphinated biquinoline to make the corresponding Re(CO)3Cl complex resulted in reduction potentials 400 mV more anodic than the neutral derivative.
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Affiliation(s)
- Ryan P King
- Department of Chemistry, University of California, Irvine Irvine CA 92697 USA
| | - Jenny Y Yang
- Department of Chemistry, University of California, Irvine Irvine CA 92697 USA
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Non-covalent interactions in transition metal-catalyzed para-selective C H functionalization of arenes. ADVANCES IN ORGANOMETALLIC CHEMISTRY 2023. [DOI: 10.1016/bs.adomc.2023.01.001] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Subscribe] [Scholar Register] [Indexed: 03/19/2023]
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Haldar C, Bisht R, Chaturvedi J, Guria S, Hassan MMM, Ram B, Chattopadhyay B. Ligand- and Substrate-Controlled para C–H Borylation of Anilines at Room Temperature. Org Lett 2022; 24:8147-8152. [DOI: 10.1021/acs.orglett.2c03188] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/05/2022]
Affiliation(s)
- Chabush Haldar
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Ranjana Bisht
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
| | - Jagriti Chaturvedi
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
| | - Saikat Guria
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
| | - Mirja Md Mahamudul Hassan
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
| | - Bali Ram
- Department of Chemistry, Institute of Science, Banaras Hindu University, Varanasi 221005, India
| | - Buddhadeb Chattopadhyay
- Department of Biological & Synthetic Chemistry, Center of Biomedical Research, SGPGIMS Campus, Raebareli Road, Lucknow 226014, Uttar Pradesh, India
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Gillespie J, Fanourakis A, Phipps RJ. Strategies That Utilize Ion Pairing Interactions to Exert Selectivity Control in the Functionalization of C-H Bonds. J Am Chem Soc 2022; 144:18195-18211. [PMID: 36178308 PMCID: PMC9562467 DOI: 10.1021/jacs.2c08752] [Citation(s) in RCA: 17] [Impact Index Per Article: 8.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 08/17/2022] [Indexed: 11/30/2022]
Abstract
Electrostatic attraction between two groups of opposite charge, typically known as ion-pairing, offers unique opportunities for the design of systems to enable selectivity control in chemical reactions. Catalysis using noncovalent interactions is an established and vibrant research area, but it is noticeable that hydrogen bonding interactions are still the main interaction of choice in system design. Opposite charges experience the powerful force of Coulombic attraction and have the ability to exert fundamental influence on the outcome of reactions that involve charged reagents, intermediates or catalysts. In this Perspective, we will examine how ion-pairing interactions have been used to control selectivity in C-H bond functionalization processes. This broad class of reactions provides an interesting and thought-provoking lens through which to examine the application of ion-pairing design strategies because it is one that encompasses great mechanistic diversity, poses significant selectivity challenges, and perhaps most importantly is of immense interest to synthetic chemists in both industry and academia. We survey reactions that proceed via radical and ionic mechanisms alongside those that involve transition metal catalysis and will deal with control of site-selectivity and enantioselectivity. We anticipate that as this emerging area develops, it will become an ever-more important design strategy for selectivity control.
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Affiliation(s)
| | | | - Robert J. Phipps
- Yusuf Hamied Department of Chemistry, University of Cambridge, Lensfield Road, Cambridge CB2 1EW, U.K.
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