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Holt E, Ruskin J, Garrison NG, Vemulapalli S, Lam W, Kiame N, Henriquez N, Borukhova F, Williams J, Dudding T, Lectka T. Photoactivated Pyridine Directed Fluorination through Hydrogen Atom Transfer. J Org Chem 2023. [PMID: 38033293 DOI: 10.1021/acs.joc.3c02146] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/02/2023]
Abstract
We have established hydrogen atom transfer (HAT) as the key player in a directed, photopromoted fluorination of pyridylic groups. The Lewis basic pyridyl nitrogen directs amine radical dication propagated HAT and Selectfluor fluorination of various ortho substituents in a highly regioselective manner with little to no side product formation. A variety of pyridines and quinolines were employed to showcase the directing capability of the nitrogen atom. Additionally, both experimental and computational data are provided that illuminate how this mechanism differs from and complements prior work in the area.
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Affiliation(s)
- Eric Holt
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Jonah Ruskin
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Nathaniel G Garrison
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Srini Vemulapalli
- Department of Chemistry, Brock University, St. Catharines, Ontario L2S3A1, Canada
| | - Winson Lam
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Neil Kiame
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Nicolas Henriquez
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Fanny Borukhova
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Jack Williams
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
| | - Travis Dudding
- Department of Chemistry, Brock University, St. Catharines, Ontario L2S3A1, Canada
| | - Thomas Lectka
- Department of Chemistry, Johns Hopkins University, 3400 North Charles St., Baltimore, Maryland 21218, United States
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Rasheed F, Shi J, Zeng T, Krishna Y, Fishlock D, Orellana A. Soft Fluorination of 4-Alkylpyridines. Org Lett 2023. [PMID: 38029416 DOI: 10.1021/acs.orglett.3c03482] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 12/01/2023]
Abstract
We report the mild and selective mono- and difluorination of 4-alkylpyridines. The process involves soft-dearomatization of pyridines to the corresponding alkylidene dihydropyridines and treatment with Selectfluor. The reaction tolerates a broad range of functional groups, including those bearing acidic and weak C-H bonds. In addition, selective fluorination of 4-alkylpyridines attached to 2-alkylpyridines and 2-alkylpyrimidines can be achieved in good yields, but a 4-alkylpyridine tethered to a 4-alkylpyrimidine is fluorinated at both heterobenzylic positions.
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Affiliation(s)
- Faizan Rasheed
- Department of Chemistry, York University, 4700 Keele Street, Toronto ON, M3J 1P3, Canada
| | - Jiaqi Shi
- Department of Chemistry, York University, 4700 Keele Street, Toronto ON, M3J 1P3, Canada
| | - Tao Zeng
- Department of Chemistry, York University, 4700 Keele Street, Toronto ON, M3J 1P3, Canada
| | - Yarkali Krishna
- Department of Chemistry, York University, 4700 Keele Street, Toronto ON, M3J 1P3, Canada
| | - Dan Fishlock
- Roche Pharma Research and Early Development, pCMC Drug Substance, Roche Innovation Center Basel, F. Hoffmann-La Roche Ltd, Grenzacherstrasse 124, CH-4070 Basel, Switzerland
| | - Arturo Orellana
- Department of Chemistry, York University, 4700 Keele Street, Toronto ON, M3J 1P3, Canada
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Yadav A, Upadhyay S, Kant R, Srivastava AK. Regioselective Synthesis of Phenanthridines via Pd(II)-Catalyzed Annulative C( sp2)-H Activation. J Org Chem 2023; 88:13568-13583. [PMID: 37738300 DOI: 10.1021/acs.joc.3c01234] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/24/2023]
Abstract
A robust synthesis of phenanthridines has been described via Pd(II)-catalyzed domino C(sp2)-H activation/N-arylation using oxime esters with aryl acyl peroxides in a highly regioselective manner. This protocol is compatible with acetophenone as well as benzophenone-derived oxime esters and allows modular construction of functionalized phenanthridines with wide tolerance of electronic functionality. Further transformations were conducted to synthesize key building blocks, and control experiments were performed to understand the plausible reaction mechanism.
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Affiliation(s)
- Anamika Yadav
- Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
| | - Surabhi Upadhyay
- Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Ruchir Kant
- Biochemistry and Structural Biology Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
| | - Ajay Kumar Srivastava
- Medicinal and Process Chemistry Division, CSIR-Central Drug Research Institute, Lucknow 226031, India
- Academy of Scientific and Innovative Research (AcSIR), Ghaziabad 201002, India
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Synthesis of mono-fluoromethyl 6,5-heteroaromatic bicycles using 1,3-difluoroacetone as a cyclising reagent. Tetrahedron Lett 2022. [DOI: 10.1016/j.tetlet.2022.154160] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/21/2022]
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