1
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Shi Y, Derasp JS, Guzman SM, Patrick BO, Hein JE. Halide Salts Alleviate TMSOK Inhibition in Suzuki-Miyaura Cross-Couplings. ACS Catal 2024; 14:12671-12680. [PMID: 39169912 PMCID: PMC11334106 DOI: 10.1021/acscatal.4c02407] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 04/23/2024] [Revised: 07/28/2024] [Accepted: 07/29/2024] [Indexed: 08/23/2024]
Abstract
The Suzuki-Miyaura cross-coupling (SMC) remains one of the most widely used transformations available to chemists. Recently, robust new conditions achieving rapid reactivity under homogeneous aprotic conditions enabled by the use of potassium trimethylsilanolate (TMSOK) as a base were reported. However, the strong inhibitory effect of TMSOK restricts the generality of such conditions. Moreover, the basic nature of TMSOK impedes the use of protic heterocycles as substrates, as these latter anionic species are even more potent catalyst inhibitors. Herein, we report a thorough mechanistic study of these novel SMC conditions. Halide salt additives were found to provide a dramatic rate acceleration and mitigate the inhibitory effect of TMSOK. NMR experiments revealed that this is largely achieved by impacting the unexpected formation of inactive [LnPd(Ar)(μ-OH)]2, favoring the formation of active LnPd(Ar)(X) instead. These findings enabled an impressive substrate scope even at low catalyst loadings (0.1 mol %). Finally, halide additives were observed to enable the use of protic heterocyclic substrates, which could otherwise completely inhibit reactivity.
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Affiliation(s)
- Yao Shi
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Joshua S. Derasp
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Sara M. Guzman
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Brian O. Patrick
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Jason E. Hein
- Department
of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Department
of Chemistry, University of Bergen, Allégaten 41, N-5007 Bergen, Norway
- Acceleration
Consortium, University of Toronto, Toronto, Ontario M5G 3H6, Canada
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2
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Cai I, Malig TC, Kurita KL, Derasp JS, Sirois LE, Hein JE. Investigating the Origin of Epimerization Attenuation during Pd-Catalyzed Cross-Coupling Reactions. ACS Catal 2024; 14:12331-12341. [PMID: 39169902 PMCID: PMC11334108 DOI: 10.1021/acscatal.4c03401] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/10/2024] [Revised: 07/24/2024] [Accepted: 07/24/2024] [Indexed: 08/23/2024]
Abstract
Palladium-catalyzed cross-couplings remain among the most robust methodologies to form carbon-carbon and carbon-heteroatom bonds. In particular, carbon-nitrogen (C-N) couplings (Buchwald-Hartwig aminations) find widespread use in fine chemicals industries. The use of base in these reactions is critical for catalyst activation and proton sequestration. Base selection also plays an important role in process design, as strongly basic conditions can impact sensitive stereocenters and result in erosion of stereochemical purity. Herein we investigate the role of a Pd catalyst in suppressing base-mediated epimerization of a sultam stereocenter during a C-N cross-coupling reaction to access the RORγ inhibitor GDC-0022. Online high-performance liquid chromatography-mass spectrometry (HPLC-MS) was employed to acquire reaction time course profiles and to delineate epimerization behavior, identify decomposition pathways, and monitor Pd-containing species. Our ability to monitor organopalladium complexes in real time by HPLC-MS provided strong evidence that the degree of epimerization was correlated to the Pd speciation in solution. Specifically, Pd(II) complexes were associated with mitigating epimerization of six-membered sultams. Additional studies showed that the suppression of epimerization in the presence of Pd(II) can impact Pd-catalyzed reactions of other substrates such as enolizable ketones, thus providing practical insight on the execution and optimization of such processes.
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Affiliation(s)
- Isabelle Cai
- Department
of Chemistry, The University of British
Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Thomas C. Malig
- Department
of Synthetic Molecule Analytical Chemistry, Genentech, Inc., South
San Francisco, California 94080, United States
| | - Kenji L. Kurita
- Department
of Synthetic Molecule Analytical Chemistry, Genentech, Inc., South
San Francisco, California 94080, United States
| | - Joshua S. Derasp
- Department
of Chemistry, The University of British
Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Lauren E. Sirois
- Department
of Synthetic Molecule Process Chemistry, Genentech, Inc., South San Francisco, California 94080, United States
| | - Jason E. Hein
- Department
of Chemistry, The University of British
Columbia, Vancouver, British Columbia V6T 1Z1, Canada
- Department
of Chemistry, University of Bergen, Bergen N-5020, Norway
- Acceleration
Consortium, The University of Toronto, Toronto, Ontario M5G 1X6, Canada
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3
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Shi Y, Derasp JS, Maschmeyer T, Hein JE. Phase transfer catalysts shift the pathway to transmetalation in biphasic Suzuki-Miyaura cross-couplings. Nat Commun 2024; 15:5436. [PMID: 38937470 PMCID: PMC11211432 DOI: 10.1038/s41467-024-49681-4] [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: 02/26/2024] [Accepted: 06/14/2024] [Indexed: 06/29/2024] Open
Abstract
The Suzuki-Miyaura coupling is a widely used C-C bond forming reaction. Numerous mechanistic studies have enabled the use of low catalyst loadings and broad functional group tolerance. However, the dominant mode of transmetalation remains controversial and likely depends on the conditions employed. Herein we detail a mechanistic study of the palladium-catalyzed Suzuki-Miyaura coupling under biphasic conditions. The use of phase transfer catalysts results in a remarkable 12-fold rate enhancement in the targeted system. A shift from an oxo-palladium based transmetalation to a boronate-based pathway lies at the root of this activity. Furthermore, a study of the impact of different water loadings reveals reducing the proportion of the aqueous phase increases the reaction rate, contrary to reaction conditions typically employed in the literature. The importance of these findings is highlighted by achieving an exceptionally broad substrate scope with benzylic electrophiles using a 10-fold reduction in catalyst loading relative to literature precedent.
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Affiliation(s)
- Yao Shi
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Joshua S Derasp
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
| | - Tristan Maschmeyer
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada
| | - Jason E Hein
- Department of Chemistry, University of British Columbia, Vancouver, BC, V6T 1Z1, Canada.
- Department of Chemistry, University of Bergen, Bergen, Norway.
- Acceleration Consortium, University of Toronto, Toronto, ON, Canada.
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4
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Ayuso-Carrillo J, Fina F, Galleposo EC, Ferreira RR, Mondal PK, Ward BD, Bonifazi D. One-Step Catalyst-Transfer Macrocyclization: Expanding the Chemical Space of Azaparacyclophanes. J Am Chem Soc 2024; 146:16440-16457. [PMID: 38848549 PMCID: PMC11191698 DOI: 10.1021/jacs.4c02319] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/15/2024] [Revised: 05/22/2024] [Accepted: 05/23/2024] [Indexed: 06/09/2024]
Abstract
In this paper, we report on a one-step catalyst-transfer macrocyclization (CTM) reaction, based on the Pd-catalyzed Buchwald-Hartwig cross-coupling reaction, selectively affording only cyclic structures. This route offers a versatile and efficient approach to synthesize aza[1n]paracyclophanes (APCs) featuring diverse functionalities and lumens. The method operates at mild reaction temperatures (40 °C) and short reaction times (∼2 h), delivering excellent isolated yields (>75% macrocycles) and up to 30% of a 6-membered cyclophane, all under nonhigh-dilution concentrations (35-350 mM). Structural insights into APCs reveal variations in product distribution based on different endocyclic substituents, with steric properties of exocyclic substituents having minimal influence on the macrocyclization. Aryl-type endocyclic substituents predominantly yield 6-membered macrocycles, while polycyclic aromatic units such as fluorene and carbazole favor 4-membered species. Experimental and computational studies support a proposed mechanism of ring-walking catalyst transfer that promotes the macrocycle formation. It has been found that the macrocyclization is driven by the formation of cyclic conformers during the oligomerization step favoring an intramolecular C-N bond formation that, depending on the cycle size, hinges on either preorganization effect or kinetic increase of the reductive elimination step or a combination of the two. The CTM process exhibits a "living" behavior, facilitating sequential synthesis of other macrocycles by introducing relevant monomers, thus providing a practical synthetic platform for chemical libraries. Notably, CTM operates both under diluted and concentrated regimes, offering scalability potential, unlike typical macrocyclization reactions usually operating in the 0.1-1 mM range.
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Affiliation(s)
- Josue Ayuso-Carrillo
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, Vienna A-1090, Austria
| | - Federica Fina
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, Vienna A-1090, Austria
| | - El Czar Galleposo
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, Vienna A-1090, Austria
| | - Rúben R. Ferreira
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, Vienna A-1090, Austria
| | - Pradip Kumar Mondal
- Elettra
Sincrotrone Trieste S.C.p.A., Strada Statale 14−km 163, 5 in Area Science
Park, Basovizza, Trieste 34149, Italy
| | - Benjamin D. Ward
- School
of Chemistry, Cardiff University, Main Building, Park Place, Cardiff CF10 3AT, U.K.
| | - Davide Bonifazi
- Institute
of Organic Chemistry, University of Vienna, Währinger Strasse 38, Vienna A-1090, Austria
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5
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Duran-Camacho G, Bland DC, Li F, Neufeldt SR, Sanford MS. Nickel-Based Catalysts for the Selective Monoarylation of Dichloropyridines: Ligand Effects and Mechanistic Insights. ACS Catal 2024; 14:6404-6412. [PMID: 38911467 PMCID: PMC11192541 DOI: 10.1021/acscatal.4c00648] [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] [Indexed: 06/25/2024]
Abstract
This report describes a detailed study of Ni phosphine catalysts for the Suzuki-Miyaura coupling of dichloropyridines with halogen-containing (hetero)aryl boronic acids. With most phosphine ligands these transformations afford mixtures of mono- and diarylated cross-coupling products as well as competing oligomerization of the boronic acid. However, a ligand screen revealed that PPh2Me and PPh3 afford high yield and selectivity for monoarylation over diarylation as well as minimal competing oligomerization of the boronic acid. Several key observations were made regarding the selectivity of these reactions, including: (1) phosphine ligands that afford high selectivity for monoarylation fall within a narrow range of Tolman cone angles (between 136° and 157°); (2) more electron-rich trialkylphosphines afford predominantly diarylated products, while less-electron rich di- and triarylphosphines favor monoarylation; (3) diarylation proceeds via intramolecular oxidative addition; and (4) the solvent (MeCN) plays a crucial role in achieving high monoarylation selectivity. Experimental and DFT studies suggest that all these data can be explained based on the reactivity of a key intermediate: a Ni0-π complex of the monoarylated product. With larger, more electron-rich trialkylphosphine ligands, this π complex undergoes intramolecular oxidative addition faster than ligand substitution by the MeCN solvent, leading to selective diarylation. In contrast, with relatively small di- and triarylphosphine ligands, associative ligand substitution by MeCN is competitive with oxidative addition, resulting in selective formation of monoarylated products. The generality of this method is demonstrated with a variety of dichloropyridines and chloro-substituted aryl boronic acids. Furthermore, the optimal ligand (PPh2Me) and solvent (MeCN) are leveraged to achieve the Ni-catalyzed monoarylation of a broader set of dichloroarene substrates.
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Affiliation(s)
- Geraldo Duran-Camacho
- Department of Chemistry, University of Michigan, 930 North Avenue, Ann Arbor, Michigan, 48104, United States
| | - Douglas C. Bland
- Product & Process Technology R&D, Corteva Agriscience, 9330 Zionsville Road, Indianapolis, Indiana, 46268, United States
| | - Fangzheng Li
- Product & Process Technology R&D, Corteva Agriscience, 9330 Zionsville Road, Indianapolis, Indiana, 46268, United States
| | - Sharon R. Neufeldt
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana, 59717, United States
| | - Melanie S. Sanford
- Department of Chemistry, University of Michigan, 930 North Avenue, Ann Arbor, Michigan, 48104, United States
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6
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Larson NG, Norman JP, Neufeldt SR. Mechanistic Origin of Ligand Effects on Exhaustive Functionalization During Pd-Catalyzed Cross-Coupling of Dihaloarenes. ACS Catal 2024; 14:7127-7135. [PMID: 38911468 PMCID: PMC11192547 DOI: 10.1021/acscatal.4c00646] [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] [Indexed: 06/25/2024]
Abstract
We describe a detailed investigation into why bulky ligands-those that enable catalysis at "12e -" Pd0-tend to promote overfunctionalization during Pd-catalyzed cross-couplings of dihalogenated substrates. After one cross-coupling event takes place, PdL initially remains coordinated to the π system of the nascent product. Selectivity for mono- vs. difunctionalization arises from the relative rates of π-decomplexation versus a second oxidative addition. Under the Suzuki coupling conditions in this work, direct dissociation of 12e - PdL from the π-complex cannot outcompete oxidative addition. Instead, Pd must be displaced from the π-complex as 14e - PdL(L') by a second incoming ligand L'. The incoming ligand is another molecule of dichloroarene if the reaction conditions do not include π-coordinating solvents or additives. More overfunctionalization tends to result when increased ligand or substrate sterics raises the energy of the bimolecular transition state for separating 14e - PdL(L') from the mono-cross-coupled product. This work has practical implications for optimizing selectivity in cross-couplings involving multiple halogens. For example, we demonstrate that small coordinating additives like DMSO can largely suppress overfunctionalization and that precatalyst structure can also impact selectivity.
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Affiliation(s)
- Nathaniel G. Larson
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - Jacob P. Norman
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States
| | - Sharon R. Neufeldt
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, MT 59717, United States
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7
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Jia C, She Y, Lu Y, Wu M, Yang X, Chen L, Li Y. Octalithium, Tetrasodium, and Decalithium Compounds Based on Pyrrolyl Ligands: Synthesis, Structures, and Activation of the C-H Bonds of Pyrrolyl Rings and C═N Bonds of a Series of Ligands by Organolithium Reagents. Inorg Chem 2023; 62:14072-14085. [PMID: 37578854 DOI: 10.1021/acs.inorgchem.3c02208] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2023]
Abstract
The organometallic compounds of lithium ions have garnered continuous interest as indispensable precursors for the syntheses of organometallic complexes of main-group metals, transition metals, lanthanide metals, and actinide metals. In this work, we present a strategy for the preparation of a series of polynuclear lithium complexes. This methodology features the utilization of organolithium reagents both as metal sources to coordinate with the ligands and as nucleophilic reagents to undergo nucleophilic addition to the C═N bonds of the ligands. Reaction of a ligand HL1 [HL1 = 2-(((1-(2-(dimethylamino)ethyl)-1H-pyrrol-2-yl)methylene)amino)phenol] with n-BuLi produced complex [Li8(L1a)4]·1.5Tol (1·1.5Tol) [H2L1a = 2-((1-(1-(2-(dimethylamino)ethyl)-1H-pyrrol-2-yl)pentyl)amino)phenol]. One prominent feature regarding the formation of 1·1.5Tol is the occurrence of nucleophilic addition of n-BuLi to the C═N bond of HL1, leading to the generation of a new [L1a]2- ligand that contains both aminophenol and 1-(2-pyrrolyl)alkylamine scaffolds. The developed protocol can be adapted to a series of organolithium reagents. Compounds [Li8(L1b)4] (2) and [Li8(L1c)4] (3) were afforded by treatment of HL1 with sec-BuLi and LiCH2SiMe3, respectively. Reaction of an analogous ligand HL2 [HL2 = 2-(((1-(2-(dimethylamino)ethyl)-1H-pyrrol-2-yl)methylene)amino)-4-methylphenol] with n-BuLi generated compound [Li8(L2a)4] (4). C═N bond activation was not observed in the reaction of HL1 with NaOtBu, and the complex [Na4(L1)4]·Tol (5·Tol) was obtained. A decanuclear complex [Li10(L3a)2(L3b)2] (6) was also prepared via the reaction of HL3 [HL3 = 2-(2-((((1H-pyrrol-2-yl)methylene)amino)methyl)-1H-pyrrol-1-yl)-N,N-dimethylethan-1-amine] with t-BuLi. A remarkable feature in terms of the synthesis of 6 is the simultaneous occurrence of hydrogen atom abstraction from the C-H bond of the pyrrolyl ring and nucleophilic addition to the C═N bond of the HL3 ligand by t-BuLi. A series of amines containing biologically and physiologically important moieties were achieved by hydrolysis of the crude products from the reactions of the HL1-HL3 ligands and organolithium reagents. This work provides an efficient approach to high-nuclearity lithium compounds as well as a series of amines.
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Affiliation(s)
- Chaohong Jia
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
| | - Yeye She
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
| | - Yanhua Lu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
| | - Mengxiang Wu
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
| | - Xiaohan Yang
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
| | - Ling Chen
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
| | - Yahong Li
- College of Chemistry, Chemical Engineering and Materials Science, Soochow University, Suzhou 215123, People's Republic of China
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8
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Deem M, Hein JE. A Method for Converting HPLC Peak Area from Online Reaction Monitoring to Concentration Using Nonlinear Regression. J Org Chem 2023; 88:1292-1297. [PMID: 36625157 PMCID: PMC9872085 DOI: 10.1021/acs.joc.2c02737] [Citation(s) in RCA: 2] [Impact Index Per Article: 2.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Abstract
Online HPLC reaction progress monitoring provides detailed data-rich profiles; however, extracting kinetic information requires ultraviolet-visible response factors to determine concentrations from peak areas. If the reaction's overall mass balance is known and some analytical trend for all relevant species can be recorded, it is possible to estimate the absolute response factors of all species using a system of linear equations. We delineate a method using the Microsoft Solver plug-in to convert time course profiles to reagent concentrations without analytical standards.
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9
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Deem MC, Cai I, Derasp JS, Prieto PL, Sato Y, Liu J, Kukor AJ, Hein JE. Best Practices for the Collection of Robust Time Course Reaction Profiles for Kinetic Studies. ACS Catal 2023. [DOI: 10.1021/acscatal.2c05045] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 01/11/2023]
Affiliation(s)
- Madeleine C. Deem
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Isabelle Cai
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Joshua S. Derasp
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Paloma L. Prieto
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Yusuke Sato
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Junliang Liu
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Andrew J. Kukor
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
| | - Jason E. Hein
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z1, Canada
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10
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Cook A, Bezaire M, Newman SG. Nickel-catalyzed desulfonylative olefination of β-hydroxysulfones. Org Chem Front 2023. [DOI: 10.1039/d2qo01999j] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/22/2023]
Abstract
A Ni-catalyzed C–O bond activation is used to access alkenes directly from β-hydroxysulfones.
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Affiliation(s)
- Adam Cook
- Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
| | - Maxwell Bezaire
- Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
| | - Stephen G. Newman
- Centre for Catalysis Research and Innovation, Department of Chemistry and Biomolecular Sciences, University of Ottawa, 10 Marie Curie, Ottawa, Ontario K1N 6N5, Canada
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11
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Norman JP, Neufeldt SR. The Road Less Traveled: Unconventional Site Selectivity in Palladium-Catalyzed Cross-Couplings of Dihalogenated N-Heteroarenes. ACS Catal 2022; 12:12014-12026. [PMID: 36741273 PMCID: PMC9894105 DOI: 10.1021/acscatal.2c03743] [Citation(s) in RCA: 5] [Impact Index Per Article: 2.5] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/07/2023]
Abstract
The vast majority (≥90%) of literature reports agree on the regiochemical outcomes of Pd-catalyzed cross-coupling reactions for most classes of dihalogenated N-heteroarenes. Despite a well-established mechanistic rationale for typical selectivity, several examples reveal that changes to the catalyst can switch site selectivity, leading to the unconventional product. In this Perspective, we survey these unusual cases in which divergent selectivity is controlled by ligands or catalyst speciation. In some cases, the mechanistic origin of inverted selectivity has been established, but in others the mechanism remains unknown. This Perspective concludes with a discussion of remaining challenges and opportunities for the field of site-selective cross-coupling. These include developing a better understanding of oxidative addition mechanisms, understanding the role of catalyst speciation on selectivity, establishing an explanation for the influence of ring substituents on regiochemical outcome, inverting selectivity for some "stubborn" classes of substrates, and minimizing unwanted over-reaction of di- and polyhalogenated substrates.
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Affiliation(s)
- Jacob P. Norman
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
| | - Sharon R. Neufeldt
- Department of Chemistry and Biochemistry, Montana State University, Bozeman, Montana 59717, United States
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12
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LaPorte AJ, Shi Y, Hein JE, Burke MD. Stereospecific Csp 3 Suzuki–Miyaura Cross-Coupling That Evades β-Oxygen Elimination. ACS Catal 2022. [DOI: 10.1021/acscatal.2c03245] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2022]
Affiliation(s)
- Antonio J. LaPorte
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
| | - Yao Shi
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Jason E. Hein
- Department of Chemistry, University of British Columbia, Vancouver, British Columbia V6T 1Z3, Canada
| | - Martin D. Burke
- Department of Chemistry, University of Illinois, Urbana, Illinois 61801, United States
- Carle Illinois College of Medicine, University of Illinois, Urbana, Illinois 61801, United States
- Department of Biochemistry, University of Illinois, Urbana, Illinois 61801, United States
- Arnold and Mabel Beckman Institute, University of Illinois, Urbana, Illinois 61801, United States
- Carl R. Woese Institute for Genomic Biology, University of Illinois, Urbana, Illinois 61801, United States
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