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Deng WH, Liao RZ. Cysteine Radical and Glutamate Collaboratively Enable C-H Bond Activation and C-N Bond Cleavage in a Glycyl Radical Enzyme HplG. J Chem Inf Model 2024; 64:4168-4179. [PMID: 38745447 DOI: 10.1021/acs.jcim.4c00122] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 05/16/2024]
Abstract
Hydroxyprolines are abundant in nature and widely utilized by many living organisms. Isomerization of trans-4-hydroxy-d-proline (t4D-HP) to generate 2-amino-4-ketopentanoate has been found to need a glycyl radical enzyme HplG, which catalyzes the cleavage of the C-N bond, while dehydration of trans-4-hydroxy-l-proline involves a homologous enzyme of HplG. Herein, molecular dynamics simulations and quantum mechanics/molecular mechanics (QM/MM) calculations are employed to understand the reaction mechanism of HplG. Two possible reaction pathways of HplG have been explored to decipher the origin of its chemoselectivity. The QM/MM calculations reveal that the isomerization proceeds via an initial hydrogen shift from the Cγ site of t4D-HP to a catalytic cysteine radical, followed by cleavage of the Cδ-N bond in t4D-HP to form a radical intermediate that captures a hydrogen atom from the cysteine. Activation of the Cδ-H bond in t4D-HP to bring about dehydration of t4D-HP possesses an extremely high energy barrier, thus rendering the dehydration pathway implausible in HplG. On the basis of the current calculations, conserved residue Glu429 plays a pivotal role in the isomerization pathway: the hydrogen bonding between it and t4D-HP weakens the hydroxyalkyl Cγ-Hγ bond, and it acts as a proton acceptor to trigger the cleavage of the C-N bond in t4D-HP. Our current QM/MM calculations rationalize the origin of the experimentally observed chemoselectivity of HplG and propose an H-bond-assisted bond activation strategy in radical-containing enzymes. These findings have general implications on radical-mediated enzymatic catalysis and expand our understanding of how nature wisely and selectively activates the C-H bond to modulate catalytic selectivity.
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Affiliation(s)
- Wen-Hao Deng
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
| | - Rong-Zhen Liao
- Key Laboratory of Material Chemistry for Energy Conversion and Storage, Ministry of Education, Hubei Key Laboratory of Bioinorganic Chemistry and Materia Medica, Hubei Key Laboratory of Materials Chemistry and Service Failure, School of Chemistry and Chemical Engineering, Huazhong University of Science and Technology, Wuhan 430074, China
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2
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Turner JA, Zipse H, Taylor MS. On the mechanism of carboxylate elimination from carbohydrate monoester-derived radicals. Org Biomol Chem 2024; 22:3225-3229. [PMID: 38597089 DOI: 10.1039/d4ob00241e] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/11/2024]
Abstract
A computational study of the mechanism of hydrogen atom transfer-induced carboxylate elimination from monoacylated 1,2-diol groups in pyranosides is presented. A comprehensive analysis of the 1,2-migration, elimination and fragmentation pathways reveals that concerted elimination via a 7-membered, hydrogen-bonded transition state is favored. Relative rates of elimination inferred from an intramolecular competition experiment are consistent with the trends obtained from the calculations.
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Affiliation(s)
- Julia A Turner
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON M5S 3H6, Canada.
| | - Hendrik Zipse
- Department Chemie, Ludwig-Maximilians-Universität München, Butenandtstrasse 5-13, Haus F, 81377 München, Germany.
| | - Mark S Taylor
- Department of Chemistry, University of Toronto, 80 St. George St, Toronto, ON M5S 3H6, Canada.
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3
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Gorelik DJ, Desai SP, Jdanova S, Turner JA, Taylor MS. Transformations of carbohydrate derivatives enabled by photocatalysis and visible light photochemistry. Chem Sci 2024; 15:1204-1236. [PMID: 38274059 PMCID: PMC10806712 DOI: 10.1039/d3sc05400d] [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: 10/12/2023] [Accepted: 12/13/2023] [Indexed: 01/27/2024] Open
Abstract
This review article highlights the diverse ways in which recent developments in the areas of photocatalysis and visible light photochemistry are impacting synthetic carbohydrate chemistry. The major topics covered are photocatalytic glycosylations, generation of radicals at the anomeric position, transformations involving radical formation at non-anomeric positions, additions to glycals, processes initiated by photocatalytic hydrogen atom transfer from sugars, and functional group interconversions at OH and SH groups. Factors influencing stereo- and site-selectivity in these processes, along with mechanistic aspects, are discussed.
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Affiliation(s)
- Daniel J Gorelik
- Department of Chemistry, University of Toronto 80 St. George St. Toronto ON M5S 3H6 Canada
| | - Shrey P Desai
- Department of Chemistry, University of Toronto 80 St. George St. Toronto ON M5S 3H6 Canada
| | - Sofia Jdanova
- Department of Chemistry, University of Toronto 80 St. George St. Toronto ON M5S 3H6 Canada
| | - Julia A Turner
- Department of Chemistry, University of Toronto 80 St. George St. Toronto ON M5S 3H6 Canada
| | - Mark S Taylor
- Department of Chemistry, University of Toronto 80 St. George St. Toronto ON M5S 3H6 Canada
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4
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Majhi J, Molander GA. Recent Discovery, Development, and Synthetic Applications of Formic Acid Salts in Photochemistry. Angew Chem Int Ed Engl 2024; 63:e202311853. [PMID: 37812639 DOI: 10.1002/anie.202311853] [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: 08/14/2023] [Revised: 10/05/2023] [Accepted: 10/09/2023] [Indexed: 10/11/2023]
Abstract
The advancement of sustainable photoredox catalysis in synthetic organic chemistry has evolved immensely because of the development of versatile and cost-effective reagents. In recent years, a substantial effort has been dedicated to exploring the utility of formic acid salts in various photochemical reactions. In this context, formates have demonstrated diverse capabilities, functioning as reductants, sources of carbonyl groups, and reagents for hydrogen atom transfer. Notably, the CO2 ⋅- radical anion derived from formate exhibits strong reductant properties for cleaving both C-X and C-O bonds. Moreover, these salts play a pivotal role in carboxylation reactions, further highlighting their significance in a variety of photochemical transformations. The ability of formates to serve as reductants, carbonyl sources, and hydrogen atom transfer reagents reveal exciting possibilities in synthetic organic chemistry. This minireview highlights an array of captivating discoveries, underscoring the crucial role of formates in diverse and distinctive photochemical methods, enabling access to a wide range of value-added compounds.
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Affiliation(s)
- Jadab Majhi
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
| | - Gary A Molander
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania 19104-6323, United States
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5
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Rubanov ZM, Levin VV, Dilman AD. One-Pot Transformation of Aldehydes to Ketones via Minisci-Type Reaction of Imines. Org Lett 2023. [PMID: 38016095 DOI: 10.1021/acs.orglett.3c03764] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/30/2023]
Abstract
A method for the conversion of aldehydes to ketones via the preliminary formation of aldiminines is described. The imines are involved in acid promoted Minisci-type reaction with alkyl radicals generated from esters of N-hydroxylphthalimide under photoredox conditions. Aminyl radical cations formed after the addition of the iminium ions are believed to be key intermediates, which determine the reaction outcome.
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Affiliation(s)
- Zakhar M Rubanov
- N. D. Zelinsky Institute of Organic Chemistry, 119991 Moscow, Leninsky prosp. 47, Russian Federation
- Mendeleev University of Chemical Technology, Miusskaya Sq., 9, Moscow 125047, Russian Federation
| | - Vitalij V Levin
- N. D. Zelinsky Institute of Organic Chemistry, 119991 Moscow, Leninsky prosp. 47, Russian Federation
| | - Alexander D Dilman
- N. D. Zelinsky Institute of Organic Chemistry, 119991 Moscow, Leninsky prosp. 47, Russian Federation
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Kostromitin VS, Sorokin AO, Levin VV, Dilman AD. C-F Activation of Fluorinated Esters Using Photocatalytically Generated Diaminoalkyl Radical. Org Lett 2023; 25:6598-6602. [PMID: 37643219 DOI: 10.1021/acs.orglett.3c02570] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/31/2023]
Abstract
A method for hydrofluoroalkylation of alkenes with trifluoroacetic esters under visible light irradiation affording difluorinated products is described. The reaction involves readily available trimethyltriazinane as a shoichiometric reducing agent, which generates a diamino-substituted alkyl radical serving as a strong electron donor. It is believed that the cleavage of the C-F bond by a triazinane-derived radical involves single electron reduction coupled with fluoride transfer.
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Affiliation(s)
- Vladislav S Kostromitin
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1-3, 119991 Moscow, Russian Federation
| | - Artem O Sorokin
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
- Department of Chemistry, Lomonosov Moscow State University, Leninskie Gory 1-3, 119991 Moscow, Russian Federation
| | - Vitalij V Levin
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
| | - Alexander D Dilman
- N. D. Zelinsky Institute of Organic Chemistry, Leninsky prosp. 47, 119991 Moscow, Russian Federation
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Witt C, Woerpel KA. Mechanistic Studies on the 1,2-Spin-Center Shift in Carbohydrate Systems with a Fluorenylcyclopropyl Radical Clock. J Org Chem 2023; 88:12802-12807. [PMID: 37606513 PMCID: PMC10476153 DOI: 10.1021/acs.joc.3c01069] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/12/2023] [Indexed: 08/23/2023]
Abstract
The mechanism of the 1,2-spin-center shift in carbohydrate systems was studied with a fluorenylcyclopropyl radical clock. The 1,2-rearrangement of the acyl fluorenylcyclopropane group without opening of the cyclopropane ring provides the strongest evidence that the 1,2-spin-center shift in carbohydrate systems occurs through a concerted transition state without the intermediacy of a 1,3-dioxolanyl radical.
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Affiliation(s)
- Collin
H. Witt
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
| | - K. A. Woerpel
- Department of Chemistry, New York University, 100 Washington Square East, New York, New York 10003, United States
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Jiang Y, Liu D, Rotella ME, Deng G, Liu Z, Chen W, Zhang H, Kozlowski MC, Walsh PJ, Yang X. Net-1,2-Hydrogen Atom Transfer of Amidyl Radicals: Toward the Synthesis of 1,2-Diamine Derivatives. J Am Chem Soc 2023; 145:16045-16057. [PMID: 37441806 PMCID: PMC10411589 DOI: 10.1021/jacs.3c04376] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/15/2023]
Abstract
Hydrogen atom transfer (HAT) processes are among the most useful approaches for the selective construction of C(sp3)-C(sp3) bonds. 1,5-HAT with heteroatom-centered radicals (O•, N•) have been well established and are favored relative to other 1,n-HAT processes. In comparison, net 1,2-HAT processes have been observed infrequently. Herein, the first amidyl radicalls are reported that preferentially undergo a net 1,2-HAT over 1,5-HAT. Beginning with single electron transfer from 2-azaallyl anions to N-alkyl N-aryloxy amides, the latter generate amidyl radicals. The amidyl radical undergoes a net-1,2-HAT to generate a C-centered radical that participates in an intermolecular radical-radical coupling with the 2-azaallyl radical to generate 1,2-diamine derivatives. Mechanistic and EPR experiments point to radical intermediates. Density functional theory calculations provide support for a base-assisted, stepwise-1,2-HAT process. It is proposed that the generation of amidyl radicals under basic conditions can be greatly expanded to access α-amino C-centered radicals that will serve as valuable synthetic intermediates.
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Affiliation(s)
- Yonggang Jiang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Dongxiang Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Madeline E. Rotella
- Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, 19104, United States
| | - Guogang Deng
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Zhengfen Liu
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Wen Chen
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Hongbin Zhang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
| | - Marisa C. Kozlowski
- Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, 19104, United States
| | - Patrick J. Walsh
- Roy and Diana Vagelos Laboratories, Penn/Merck Laboratory for High-Throughput Experimentation, Department of Chemistry, University of Pennsylvania, 231 South 34th Street, Philadelphia, Pennsylvania, 19104, United States
| | - Xiaodong Yang
- Key Laboratory of Medicinal Chemistry for Natural Resource, Ministry of Education; Yunnan Provincial Center for Research & Development of Natural Products; School of Pharmacy, Yunnan University, Kunming, 650500, P. R. China
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9
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Matsuo B, Majhi J, Granados A, Sharique M, Martin RT, Gutierrez O, Molander GA. Transition metal-free photochemical C-F activation for the preparation of difluorinated-oxindole derivatives. Chem Sci 2023; 14:2379-2385. [PMID: 36873833 PMCID: PMC9977406 DOI: 10.1039/d2sc06179a] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/09/2022] [Accepted: 02/02/2023] [Indexed: 02/11/2023] Open
Abstract
The development of strategies for single and selective C-F bond activation represents an important avenue to overcome limitations in the synthesis of valuable fluorine-containing compounds. The synthetic and medicinal research communities would benefit from new routes that access such relevant molecules in a simple manner. Herein we disclose a straightforward and mechanistically distinct pathway to generate gem-difluoromethyl radicals and their installation onto N-arylmethacrylamides for the preparation of valuable difluorinated oxindole derivatives. To achieve operational simplicity, the use of a readily available benzenethiol as a photocatalyst under open-to-air conditions was developed, demonstrating the facile multigram preparation of the targeted fluorinated molecules. Additionally, dispersion-corrected density functional theory (DFT) and empirical investigations provide a new basis to support the proposed reaction pathway, indicating that arene thiolate is an efficient organophotocatalyst for this transformation.
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Affiliation(s)
- Bianca Matsuo
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 USA
| | - Jadab Majhi
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 USA
| | - Albert Granados
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 USA
| | - Mohammed Sharique
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 USA
| | - Robert T Martin
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive College Park Maryland 20742 USA
| | - Osvaldo Gutierrez
- Department of Chemistry and Biochemistry, University of Maryland, 8051 Regents Drive College Park Maryland 20742 USA.,Department of Chemistry, Texas A&M University 580 Ross St. College Station Texas 77843 USA
| | - Gary A Molander
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania 231 South 34th Street Philadelphia Pennsylvania 19104-6323 USA
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Meyer F, Halasyamani PS, Masson G. Advances in Organic and Inorganic Photoredox Catalysis. ACS ORGANIC & INORGANIC AU 2022; 3:1-3. [PMID: 36855535 PMCID: PMC9954384 DOI: 10.1021/acsorginorgau.2c00062] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Download PDF] [Subscribe] [Scholar Register] [Received: 11/29/2022] [Indexed: 12/13/2022]
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11
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Shreiber ST, Granados A, Matsuo B, Majhi J, Campbell MW, Patel S, Molander GA. Visible-Light-Induced C-F Bond Activation for the Difluoroalkylation of Indoles. Org Lett 2022; 24:8542-8546. [PMID: 36373860 PMCID: PMC10414767 DOI: 10.1021/acs.orglett.2c03549] [Citation(s) in RCA: 12] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [MESH Headings] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/16/2022]
Abstract
An aryl disulfide mediated C-F bond activation of the trifluoromethyl group to generate valuable gem-difluoroalkylindoles is described. This method relies on readily available commodity reagents under mild reaction conditions and represents the first transition-metal-free redox-neutral C-F bond activation strategy. The reaction employs various substituted indoles and α-fluoro-substituted esters. Further, this mode of C-F activation was also amenable to the activation of trifluoromethylated arenes for the preparation of bis-benzylic gem-difluoromethylenes between indole and arene substructures, providing access to a unique chemical space.
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Affiliation(s)
- Scott T Shreiber
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Albert Granados
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Bianca Matsuo
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Jadab Majhi
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Mark W Campbell
- Roy and Diana Vagelos Laboratories, Department of Chemistry, University of Pennsylvania, Philadelphia, Pennsylvania 19104-6323, United States
| | - Shivani Patel
- 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
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