1
|
Youshaw C, Yang MH, Gogoi AR, Rentería-Gómez A, Liu L, Morehead LM, Gutierrez O. Iron-Catalyzed Enantioselective Multicomponent Cross-Couplings of α-Boryl Radicals. Org Lett 2023; 25:8320-8325. [PMID: 37956189 PMCID: PMC10863393 DOI: 10.1021/acs.orglett.3c03387] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 10/13/2023] [Revised: 11/03/2023] [Accepted: 11/07/2023] [Indexed: 11/15/2023]
Abstract
Despite recent interest in the development of iron-catalyzed transformations, methods that use iron-based catalysts capable of controlling the enantioselectivity in carbon-carbon cross-couplings are underdeveloped. Herein, we report a practical and simple protocol that uses commercially available and expensive iron salts in combination with chiral bisphosphine ligands to enable the regio- and enantioselective (up to 91:9) multicomponent cross-coupling of vinyl boronates, (fluoro)alkyl halides, and Grignard reagents. Preliminary mechanistic studies are consistent with rapid formation of an α-boryl radical followed by reversible radical addition to monoaryl bisphosphine-Fe(II) and subsequent enantioselective inner-sphere reductive elimination. From a broader perspective, this work provides a blueprint to develop asymmetric Fe-catalyzed multicomponent cross-couplings via the use of alkenes as linchpins to translocate alkyl radicals, modify their steric and electronic properties, and induce stereocontrol.
Collapse
Affiliation(s)
| | | | | | | | - Lei Liu
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
| | - Lukas M. Morehead
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
| | - Osvaldo Gutierrez
- Department of Chemistry, Texas A&M University, College
Station, Texas 77843, United States
| |
Collapse
|
2
|
Aguilera M, Gogoi AR, Lee W, Liu L, Brennessel WW, Gutierrez O, Neidig ML. Insight into Radical Initiation, Solvent Effects, and Biphenyl Production in Iron-Bisphosphine Cross-Couplings. ACS Catal 2023; 13:8987-8996. [PMID: 37441237 PMCID: PMC10334425 DOI: 10.1021/acscatal.3c02008] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/04/2023] [Revised: 05/31/2023] [Indexed: 07/15/2023]
Abstract
Iron-bisphosphines have attracted broad interest as highly effective and versatile catalytic systems for two- and three-component cross-coupling strategies. While recent mechanistic studies have defined the role of organoiron(II)-bisphosphine species as key intermediates for selective cross-coupled product formation in these systems, mechanistic features that are essential for catalytic performance remain undefined. Specifically, key questions include the following: what is the generality of iron(II) intermediates for radical initiation in cross-couplings? What factors control reactivity toward homocoupled biaryl side-products in these systems? Finally, what are the solvent effects in these reactions that enable high catalytic performance? Herein, we address these key questions by examining the mechanism of enantioselective coupling between α-chloro- and α-bromoalkanoates and aryl Grignard reagents catalyzed by chiral bisphosphine-iron complexes. By employing freeze-trapped 57Fe Mössbauer and EPR studies combined with inorganic synthesis, X-ray crystallography, reactivity studies, and quantum mechanical calculations, we define the key in situ iron speciation as well as their catalytic roles. In contrast to iron-SciOPP aryl-alkyl couplings, where monophenylated species were found to be the predominant reactive intermediate or prior proposals of reduced iron species to initiate catalysis, the enantioselective system utilizes an iron(II)-(R,R)-BenzP* bisphenylated intermediate to initiate the catalytic cycle. A profound consequence of this radical initiation process is that halogen abstraction and subsequent reductive elimination result in considerable amounts of biphenyl side products, limiting the efficiency of this method. Overall, this study offers key insights into the broader role of iron(II)-bisphosphine species for radical initiation, factors contributing to biphenyl side product generation, and protocol effects (solvent, Grignard reagent addition rate) that are critical to minimizing biphenyl generation to obtain more selective cross-coupling methods.
Collapse
Affiliation(s)
- Maria
Camila Aguilera
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Achyut Ranjan Gogoi
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - Wes Lee
- Department
of Chemistry and Biochemistry, University
of Maryland, College Park, Maryland 20742, United States
| | - Lei Liu
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
| | - William W. Brennessel
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
| | - Osvaldo Gutierrez
- Department
of Chemistry, Texas A&M University, College Station, Texas 77843, United States
- Department
of Chemistry and Biochemistry, University
of Maryland, College Park, Maryland 20742, United States
| | - Michael L. Neidig
- Department
of Chemistry, University of Rochester, Rochester, New York 14627, United States
- Inorganic
Chemistry Laboratory, Department of Chemistry, University of Oxford, South Parks Road, Oxford OX1 3QR, U.K.
| |
Collapse
|
3
|
Ma X, Wang H, Liu Y, Zhao X, Zhang J. Mixed Alkyl/Aryl Diphos Ligands for Iron‐Catalyzed Negishi and Kumada Cross Coupling Towards the Synthesis of Diarylmethane. ChemCatChem 2021. [DOI: 10.1002/cctc.202101237] [Citation(s) in RCA: 3] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/11/2022]
Affiliation(s)
- Xufeng Ma
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular Engineering East China University of Science and Technology 130 Mei Long Road Shanghai 200237 P. R. China
| | - Han Wang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular Engineering East China University of Science and Technology 130 Mei Long Road Shanghai 200237 P. R. China
| | - Yao Liu
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular Engineering East China University of Science and Technology 130 Mei Long Road Shanghai 200237 P. R. China
| | - Xing Zhao
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular Engineering East China University of Science and Technology 130 Mei Long Road Shanghai 200237 P. R. China
| | - Jun Zhang
- Key Laboratory for Advanced Materials and Joint International Research Laboratory of Precision Chemistry and Molecular Engineering Feringa Nobel Prize Scientist Joint Research Center School of Chemistry and Molecular Engineering East China University of Science and Technology 130 Mei Long Road Shanghai 200237 P. R. China
| |
Collapse
|
4
|
Liu L, Aguilera MC, Lee W, Youshaw CR, Neidig ML, Gutierrez O. General method for iron-catalyzed multicomponent radical cascades-cross-couplings. Science 2021; 374:432-439. [PMID: 34672739 DOI: 10.1126/science.abj6005] [Citation(s) in RCA: 12] [Impact Index Per Article: 4.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/03/2023]
Abstract
[Figure: see text].
Collapse
Affiliation(s)
- Lei Liu
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | | | - Wes Lee
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Cassandra R Youshaw
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA
| | - Michael L Neidig
- Department of Chemistry, University of Rochester, Rochester, NY 14627, USA
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, MD 20742, USA.,Department of Chemistry, Texas A&M University, College Station, TX 77843, USA
| |
Collapse
|
5
|
Liu L, Lee W, Youshaw CR, Yuan M, Geherty MB, Zavalij PY, Gutierrez O. Fe-catalyzed three-component dicarbofunctionalization of unactivated alkenes with alkyl halides and Grignard reagents. Chem Sci 2020; 11:8301-8305. [PMID: 34094183 PMCID: PMC8163237 DOI: 10.1039/d0sc02127j] [Citation(s) in RCA: 18] [Impact Index Per Article: 4.5] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/14/2020] [Accepted: 07/21/2020] [Indexed: 12/30/2022] Open
Abstract
A highly chemoselective iron-catalyzed three-component dicarbofunctionalization of unactivated olefins with alkyl halides (iodides and bromides) and sp2-hybridized Grignard reagents is reported. The reaction operates under fast turnover frequency and tolerates a diverse range of sp2-hybridized nucleophiles (electron-rich and electron-deficient (hetero)aryl and alkenyl Grignard reagents), alkyl halides (tertiary alkyl iodides/bromides and perfluorinated bromides), and unactivated olefins bearing diverse functional groups including tethered alkenes, ethers, protected alcohols, aldehydes, and amines to yield the desired 1,2-alkylarylated products with high regiocontrol. Further, we demonstrate that this protocol is amenable for the synthesis of new (hetero)carbocycles including tetrahydrofurans and pyrrolidines via a three-component radical cascade cyclization/arylation that forges three new C-C bonds.
Collapse
Affiliation(s)
- Lei Liu
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Wes Lee
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Cassandra R Youshaw
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Mingbin Yuan
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Michael B Geherty
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Peter Y Zavalij
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| |
Collapse
|
6
|
Yuan M, Song Z, Badir SO, Molander GA, Gutierrez O. On the Nature of C(sp 3)-C(sp 2) Bond Formation in Nickel-Catalyzed Tertiary Radical Cross-Couplings: A Case Study of Ni/Photoredox Catalytic Cross-Coupling of Alkyl Radicals and Aryl Halides. J Am Chem Soc 2020; 142:7225-7234. [PMID: 32195579 PMCID: PMC7909746 DOI: 10.1021/jacs.0c02355] [Citation(s) in RCA: 130] [Impact Index Per Article: 32.5] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/12/2022]
Abstract
The merger of photoredox and nickel catalysis has enabled the construction of quaternary centers. However, the mechanism, role of the ligand, and effect of the spin state for this transformation and related Ni-catalyzed cross-couplings involving tertiary alkyl radicals in combination with bipyridine and diketonate ligands remain unknown. Several mechanisms have been proposed, all invoking a key Ni(III) species prior to undergoing irreversible inner-sphere reductive elimination. In this work, we have used open-shell dispersion-corrected DFT calculations, quasi-classical dynamics calculations, and experiments to study in detail the mechanism of carbon-carbon bond formation in Ni bipyridine- and diketonate-based catalytic systems. These calculations revealed that access to high spin states (e.g., triplet spin state tetrahedral Ni(II) species) is critical for effective radical cross-coupling of tertiary alkyl radicals. Further, these calculations revealed a disparate mechanism for the C-C bond formation. Specifically, contrary to the neutral Ni-bipyridyl system, diketonate ligands lead directly to the corresponding tertiary radical cross-coupling products via an outer-sphere reductive elimination step via triplet spin state from the Ni(III) intermediates. Implications to related Ni-catalyzed radical cross-couplings and the design of new transformations are discussed.
Collapse
Affiliation(s)
- Mingbin Yuan
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Zhihui Song
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| | - Shorouk O. Badir
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Gary A. Molander
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland, College Park, Maryland 20742, United States
| |
Collapse
|
7
|
Liu L, Lee W, Yuan M, Acha C, Geherty MB, Williams B, Gutierrez O. Intra- and intermolecular Fe-catalyzed dicarbofunctionalization of vinyl cyclopropanes. Chem Sci 2020; 11:3146-3151. [PMID: 34122819 PMCID: PMC8157325 DOI: 10.1039/d0sc00467g] [Citation(s) in RCA: 17] [Impact Index Per Article: 4.3] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/25/2020] [Accepted: 02/18/2020] [Indexed: 01/01/2023] Open
Abstract
Design and implementation of the first (asymmetric) Fe-catalyzed intra- and intermolecular difunctionalization of vinyl cyclopropanes (VCPs) with alkyl halides and aryl Grignard reagents has been realized via a mechanistically driven approach. Mechanistic studies support the diffusion of alkyl radical intermediates out of the solvent cage to participate in an intra- or intermolecular radical cascade with a range of VCPs followed by re-entering the Fe radical cross-coupling cycle to undergo (stereo)selective C(sp2)-C(sp3) bond formation. This work provides a proof-of-concept of the use of vinyl cyclopropanes as synthetically useful 1,5-synthons in Fe-catalyzed conjunctive cross-couplings with alkyl halides and aryl/vinyl Grignard reagents. Overall, we provide new design principles for Fe-mediated radical processes and underscore the potential of using combined computations and experiments to accelerate the development of challenging transformations.
Collapse
Affiliation(s)
- Lei Liu
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Wes Lee
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Mingbin Yuan
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Chris Acha
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Michael B Geherty
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Brandon Williams
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland College Park Maryland 20742 USA
| |
Collapse
|