1
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Horchar AH, Dean JE, Lake AR, Carsley JE, Lillevig TR, Liu S, Petersen KS. Synthesis of Lactams via a Chiral Phosphoric Acid-Catalyzed Aniline Cyclization. J Org Chem 2024; 89:12725-12738. [PMID: 39120519 PMCID: PMC11382273 DOI: 10.1021/acs.joc.4c01060] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/10/2024]
Abstract
The enantioenriched lactams disclosed in this work are synthesized concisely in four steps. In the penultimate reaction, a benzylamine species complexes with a chiral phosphoric acid to produce benzo-fused δ-lactams equipped with an all-carbon quaternary stereocenter. Partial and full reductions were carried out on the ester and amide moieties, and a Suzuki-Miyaura cross-coupling expanded the molecule from the aromatic ring. Finally, our method was successful at a >1 g scale, indicating that the method has important practical use.
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Affiliation(s)
- Abigail H Horchar
- Department of Chemistry and Biochemistry, The University of North Carolina at Greensboro, 301 McIver Street, Greensboro, North Carolina 27412, United States
| | - Jonathan E Dean
- Department of Chemistry and Biochemistry, The University of North Carolina at Greensboro, 301 McIver Street, Greensboro, North Carolina 27412, United States
| | - Alexander R Lake
- Department of Chemistry and Biochemistry, The University of North Carolina at Greensboro, 301 McIver Street, Greensboro, North Carolina 27412, United States
| | - Jessica E Carsley
- Department of Chemistry and Biochemistry, The University of North Carolina at Greensboro, 301 McIver Street, Greensboro, North Carolina 27412, United States
| | - Tiana R Lillevig
- Department of Chemistry and Biochemistry, The University of North Carolina at Greensboro, 301 McIver Street, Greensboro, North Carolina 27412, United States
| | - Shubin Liu
- Department of Chemistry, The University of North Carolina at Chapel Hill, 125 South Road, Chapel Hill, North Carolina 27514, United States
| | - Kimberly S Petersen
- Department of Chemistry and Biochemistry, The University of North Carolina at Greensboro, 301 McIver Street, Greensboro, North Carolina 27412, United States
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2
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Zou XY, Sun Q, Hong P, Xiao YT, Luo YD, Lu X, Li JH, Song RJ. Theoretical Insights into the Mechanism and Origin of Solvent-Dependent Selectivity in the Cyclization of Propargyl Alcohols for the Divergent Synthesis of N-Heterocycles. J Phys Chem A 2024; 128:6729-6738. [PMID: 39109870 DOI: 10.1021/acs.jpca.4c04993] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 08/16/2024]
Abstract
This study elucidates the mechanisms and principles governing chemoselectivity in synthesizing two distinct N-heterocycles, benzimidazole thiazine and benzothiazole imidazole, through BF3•OEt2-catalyzed cyclization reactions of propargyl alcohols with benzimidazole thiols. Employing density functional theory calculations, we highlight the crucial role of fluorine source in influencing chemoselectivity. In DCM, BF3, as the catalytic center, coordinates with propargyl alcohol's hydroxyl group to form a precursor. Conversely, in DMF, [BF2•DMF]+, formed from DMF and BF3•OEt2, acts as the catalytic center, activating the propargyl alcohol's hydroxyl group. The mechanisms in both solvents involve sequential steps: B-O bond formation, C-O bond cleavage, S-C bond formation, hydrogen atom transfer (HAT), cyclization, and deprotonation. A notable difference is the HAT process: in DCM, it follows a 1,5-HAT process, while in DMF, BF4- formation from DMF and BF3•OEt2 provides a fluorine source and introduces steric hindrance, favoring a 1,6-HAT process and leading to unique chemoselectivity. This pioneering research showcases the impact of DMF on cyclization reactions, offering valuable insights for comprehending and designing reactions driven by fluorine sources. Crucially, our results propose an innovative reaction mechanism featuring lower potential energy surfaces, enhancing our understanding of the intricate interplay among reactants, catalysts, and solvents.
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Affiliation(s)
- Xiu-Yuan Zou
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, China
| | - Qing Sun
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, China
- Foshan (Southern China) Institute for New Materials, Foshan 528200, China
| | - Pan Hong
- State Key Laboratory of Physical Chemistry of Solid Surface, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Yu-Ting Xiao
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, China
| | - Yi-Dong Luo
- Foshan (Southern China) Institute for New Materials, Foshan 528200, China
| | - Xin Lu
- State Key Laboratory of Physical Chemistry of Solid Surface, Department of Chemistry, College of Chemistry and Chemical Engineering, Xiamen University, Xiamen 361005, China
| | - Jin-Heng Li
- State Key Laboratory Base of Eco-Chemical Engineering, College of Chemical Engineering, Qingdao University of Science and Technology, Qingdao 266042, China
- State Key Laboratory of Applied Organic Chemistry, Lanzhou University, Lanzhou 730000, China
- School of Chemistry and Chemical Engineering, Henan Normal University, Xinxiang, Henan 453007, China
| | - Ren-Jie Song
- Key Laboratory of Jiangxi Province for Persistent Pollutants Control and Resources Recycle, Nanchang Hangkong University, Nanchang 330063, China
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3
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Zhu Y, Jia J, Song X, Gong C, Xia Y. Double strain-release enables formal C-O/C-F and C-N/C-F ring-opening metathesis. Chem Sci 2024:d4sc03624g. [PMID: 39129767 PMCID: PMC11310891 DOI: 10.1039/d4sc03624g] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 06/03/2024] [Accepted: 07/20/2024] [Indexed: 08/13/2024] Open
Abstract
Metathesis reactions have been established as a powerful tool in organic synthesis. While great advances were achieved in double-bond metathesis, like olefin metathesis and carbonyl metathesis, single-bond metathesis has received less attention in the past decade. Herein, we describe the first C(sp3)-O/C(sp3)-F bond formal cross metathesis reaction between gem-difluorinated cyclopropanes (gem-DFCPs) and epoxides under rhodium catalysis. The reaction involves the formation of a highly electrophilic fluoroallyl rhodium intermediate, which is capable of reacting with the oxygen atom in epoxides as weak nucleophiles followed by C-F bond reconstruction. The use of two strained ring substrates is the key to the success of the formal cross metathesis, in which the double strain release accounts for the driving force of the transformation. Additionally, azetidine also proves to be a suitable substrate for this transformation. The reaction offers a novel approach for the metathesis of C(sp3)-O and C(sp3)-N bonds, presenting new opportunities for single-bond metathesis.
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Affiliation(s)
- Yulei Zhu
- West China School of Public Health and West China Fourth Hospital, West China-PUMC C. C. Chen Institute of Health, State Key Laboratory of Biotherapy, Sichuan University Chengdu 610041 China
| | - Jie Jia
- West China School of Public Health and West China Fourth Hospital, West China-PUMC C. C. Chen Institute of Health, State Key Laboratory of Biotherapy, Sichuan University Chengdu 610041 China
| | - Xiangyu Song
- West China School of Public Health and West China Fourth Hospital, West China-PUMC C. C. Chen Institute of Health, State Key Laboratory of Biotherapy, Sichuan University Chengdu 610041 China
| | - Chunyu Gong
- West China School of Public Health and West China Fourth Hospital, West China-PUMC C. C. Chen Institute of Health, State Key Laboratory of Biotherapy, Sichuan University Chengdu 610041 China
| | - Ying Xia
- West China School of Public Health and West China Fourth Hospital, West China-PUMC C. C. Chen Institute of Health, State Key Laboratory of Biotherapy, Sichuan University Chengdu 610041 China
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4
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Jabbarpoor M, LeBlanc J, Chen Z, Cadwallader D, Le CM. Pd-catalyzed Suzuki-type cross-coupling of 2-pyridyl carbamoyl fluorides. Chem Commun (Camb) 2024. [PMID: 39054900 DOI: 10.1039/d4cc02431a] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/27/2024]
Abstract
We describe a palladium-catalyzed Suzuki-type cross-coupling reaction of 2-pyridyl carbamoyl fluorides with boronic acids, which provides entry to medicinally relevant pyridyl amides. Mechanistic studies, including the synthesis and reactivity of carbamoyl Pd-F complexes, reveal the importance of both the fluoride electrophile and nitrogen directing group for aiding reactivity.
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Affiliation(s)
- Maryam Jabbarpoor
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Jesse LeBlanc
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Zichuan Chen
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Dusty Cadwallader
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
| | - Christine M Le
- Department of Chemistry, York University, 4700 Keele Street, Toronto, ON, M3J 1P3, Canada.
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5
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Pulikkottil F, Burnett JS, Saiter J, Goodall CAI, Claringbold B, Lam K. eFluorination for the Rapid Synthesis of Carbamoyl Fluorides from Oxamic Acids. Org Lett 2024; 26:6103-6108. [PMID: 39016380 PMCID: PMC11287745 DOI: 10.1021/acs.orglett.4c01605] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 05/08/2024] [Revised: 06/12/2024] [Accepted: 06/13/2024] [Indexed: 07/18/2024]
Abstract
In this letter, we disclose the anodic oxidation of oxamic acids in the presence of Et3N·3HF as a practical, scalable, and robust method to rapidly access carbamoyl fluorides from readily available and stable precursors. The simplicity of this method also led us to develop the first flow electrochemical preparation of carbamoyl fluorides, demonstrating scale-up feasibility as a proof of concept.
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Affiliation(s)
| | | | - Jérémy Saiter
- School of Science, Faculty
of Engineering and Science, University of
Greenwich, Chatham Maritime, Chatham, Kent ME4 4TB, United Kingdom
| | - Charles A. I. Goodall
- School of Science, Faculty
of Engineering and Science, University of
Greenwich, Chatham Maritime, Chatham, Kent ME4 4TB, United Kingdom
| | - Bini Claringbold
- School of Science, Faculty
of Engineering and Science, University of
Greenwich, Chatham Maritime, Chatham, Kent ME4 4TB, United Kingdom
| | - Kevin Lam
- School of Science, Faculty
of Engineering and Science, University of
Greenwich, Chatham Maritime, Chatham, Kent ME4 4TB, United Kingdom
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6
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Garg A, Haswell A, Hopkinson MN. C-F Bond Insertion: An Emerging Strategy for Constructing Fluorinated Molecules. Chemistry 2024; 30:e202304229. [PMID: 38270496 DOI: 10.1002/chem.202304229] [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: 12/19/2023] [Revised: 01/24/2024] [Accepted: 01/25/2024] [Indexed: 01/26/2024]
Abstract
C-F Insertion reactions, where an organic fragment formally inserts into a carbon-fluorine bond in a substrate, are highly attractive, yet largely unexplored, methods to prepare valuable fluorinated molecules. The inherent strength of C-F bonds and the resulting need for a large thermodynamic driving force to initiate C-F cleavage often leads to sequestering of the released fluoride in an unreactive by-product. Recently, however, several groups have succeeded in overcoming this challenge, opening up the study of C-F insertion as an efficient and highly atom-economical approach to prepare fluorinated compounds. In this article, the recent breakthroughs are discussed focusing on the key conceptual advances that allowed for both C-F bond cleavage and subsequent incorporation of the released fluoride into the product.
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Affiliation(s)
- Arushi Garg
- School of Natural and Environmental Sciences, Newcastle University, Bedson Building, NE1 7RU, Newcastle Upon Tyne, UK
| | - Alex Haswell
- School of Natural and Environmental Sciences, Newcastle University, Bedson Building, NE1 7RU, Newcastle Upon Tyne, UK
| | - Matthew N Hopkinson
- School of Natural and Environmental Sciences, Newcastle University, Bedson Building, NE1 7RU, Newcastle Upon Tyne, UK
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7
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Schmitt HL, Martymianov D, Green O, Delcaillau T, Park Kim YS, Morandi B. Regiodivergent Ring-Expansion of Oxindoles to Quinolinones. J Am Chem Soc 2024; 146:4301-4308. [PMID: 38335924 PMCID: PMC10885155 DOI: 10.1021/jacs.3c12119] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 02/12/2024]
Abstract
The development of divergent methods to expedite structure-activity relationship studies is crucial to streamline discovery processes. We developed a rare example of regiodivergent ring expansion to access two regioisomers from a common starting material. To enable this regiodivergence, we identified two distinct reaction conditions for transforming oxindoles into quinolinone isomers. The presented methods proved to be compatible with a variety of functional groups, which enabled the late-stage diversification of bioactive oxindoles as well as facilitated the synthesis of quinolinone drugs and their derivatives.
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Affiliation(s)
- Hendrik L Schmitt
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Den Martymianov
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Ori Green
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Tristan Delcaillau
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Young Seo Park Kim
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
| | - Bill Morandi
- Laboratorium für Organische Chemie, ETH Zürich, Vladimir-Prelog-Weg 3, HCI, 8093 Zürich, Switzerland
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8
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Vogel J, Miller KF, Shin E, Krussman JM, Melvin PR. Expanded Access to Fluoroformamidines via a Modular Synthetic Pathway. Org Lett 2024; 26:1277-1281. [PMID: 38323858 PMCID: PMC10877594 DOI: 10.1021/acs.orglett.4c00131] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/11/2024] [Revised: 02/01/2024] [Accepted: 02/05/2024] [Indexed: 02/08/2024]
Abstract
Fluoroformamidines are an underutilized and understudied functional group despite combining two of the most highly prized elements in drug design: nitrogen and fluorine. We report a practical and modular synthesis of fluoroformamidines via the rearrangement of in situ-generated amidoximes. High yields in just 60 s at room temperature highlight the efficiency of this protocol. Furthermore, fluoroformamidines proved to be useful intermediates in the synthesis of diverse ureas and carbamimidates.
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Affiliation(s)
- James
A. Vogel
- Department
of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Kirya F. Miller
- Department
of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Eunjeong Shin
- Department
of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Jenna M. Krussman
- Department
of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
| | - Patrick R. Melvin
- Department
of Chemistry, Bryn Mawr College, Bryn Mawr, Pennsylvania 19010, United States
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9
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Farley SES, Mulryan D, Rekhroukh F, Phanopoulos A, Crimmin MR. Catalytic HF Shuttling between Fluoroalkanes and Alkynes. Angew Chem Int Ed Engl 2023:e202317550. [PMID: 38069591 DOI: 10.1002/anie.202317550] [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: 11/17/2023] [Indexed: 12/23/2023]
Abstract
In this paper, we report BF3 ⋅ OEt2 as a catalyst to shuttle equivalents of HF from a fluoroalkane to an alkyne. Reactions of terminal and internal aliphatic alkynes led to formation of difluoroalkane products, while diarylalkynes can be selectively converted into fluoroalkenes. The method tolerates numerous sensitive functional groups including halogen, protected amine, ester and thiophene substituents. Mechanistic studies (DFT, probe experiments) suggest the catalyst is involved in both the defluorination and fluorination steps, with BF3 acting as a Lewis acid and OEt2 a weak Lewis base that mediates proton transfer. In certain cases, the interconversion of fluoroalkene and difluoroalkane products was found to be reversible. The new catalytic system was applied to demonstrate proof-of-concept recycling of poly(vinylidene difluoride).
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Affiliation(s)
- Shannon E S Farley
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK
| | - Daniel Mulryan
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK
| | - Feriel Rekhroukh
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK
| | - Andreas Phanopoulos
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK
| | - Mark R Crimmin
- Department of Chemistry, Imperial College London, Molecular Sciences Research Hub, 82 Wood Lane, Shepherds Bush, London, W12 0BZ, UK
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10
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Yu X, Maity A, Studer A. Cooperative Photoredox and N-Heterocyclic Carbene Catalyzed Fluoroaroylation for the Synthesis of α-Trifluoromethyl-Substituted Ketones. Angew Chem Int Ed Engl 2023; 62:e202310288. [PMID: 37812525 DOI: 10.1002/anie.202310288] [Citation(s) in RCA: 6] [Impact Index Per Article: 6.0] [Reference Citation Analysis] [Abstract] [Key Words] [Grants] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 07/19/2023] [Revised: 10/08/2023] [Accepted: 10/09/2023] [Indexed: 10/11/2023]
Abstract
α-Trifluoromethylated ketones have attracted significant attention as valuable building blocks in organic synthesis. Such compounds are generally accessed through trifluoromethylation of ketones. Here we report an alternative disconnection approach for the construction of α-CF3 carbonyl compounds by using aroyl fluorides as bifunctional reagents for fluoroaroylation of gem-difluoroalkenes through cooperative photoredox and N-heterocyclic carbene (NHC) catalysis. This strategy bypasses the use of expensive or sensitive trifluoromethylation reagents and/or the requirement for ketone pre-functionalization, thus enabling an efficient and general synthetic method to access α-CF3 -substituted ketones. A wide variety of gem-difluoroalkenes and aroyl fluorides bearing a diverse set of functional groups are eligible substrates. Notably, the developed methodology also provides rapid access to mono- or difluoroalkyl ketones. Mechanistic studies reveal that merging photoredox catalysis with NHC catalysis is essential for the reaction.
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Affiliation(s)
- Xiaoye Yu
- Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
| | - Anirban Maity
- Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
| | - Armido Studer
- Organisch-Chemisches Institut, Universität Münster, Corrensstrasse 40, 48149, Münster, Germany
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11
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Cho H, Jang S, Lee K, Cha D, Min SJ. Visible-Light-Induced DDQ-Catalyzed Fluorocarbamoylation Using CF 3SO 2Na and Oxygen. Org Lett 2023. [PMID: 37987781 DOI: 10.1021/acs.orglett.3c03335] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 11/22/2023]
Abstract
The synthesis of carbamoyl fluorides via visible-light induced DDQ catalysis of secondary amines is described. This protocol employs sodium trifluorosulfinate and molecular oxygen for the in situ generation of carbonyl difluoride, which is reacted with amines to afford the corresponding carbamoyl fluorides efficiently. Moreover, carbamoyl fluorides are easily transformed to synthetically useful carbonyl compounds under mild reaction conditions.
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Affiliation(s)
- Huijeong Cho
- Department of Applied Chemistry, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
- Center for Bionano Intelligence Education and Research, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Seonga Jang
- Department of Applied Chemistry, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
- Center for Bionano Intelligence Education and Research, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Kangjoo Lee
- Department of Applied Chemistry, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
- Center for Bionano Intelligence Education and Research, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Dohoon Cha
- Department of Applied Chemistry, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
- Center for Bionano Intelligence Education and Research, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
| | - Sun-Joon Min
- Department of Applied Chemistry, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
- Center for Bionano Intelligence Education and Research, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
- Department of Chemical & Molecular Engineering, Hanyang University ERICA, Ansan, Gyeonggi-do 15588, Republic of Korea
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12
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Cadwallader D, Shevchuk D, Tiburcio TR, Le CM. Fluoride-Catalyzed Cross-Coupling of Carbamoyl Fluorides and Alkynylsilanes. Org Lett 2023; 25:7369-7373. [PMID: 37767985 DOI: 10.1021/acs.orglett.3c02871] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 09/29/2023]
Abstract
We report the synthesis of alkynamides via the cross-coupling of carbamoyl fluorides and alkynylsilanes catalyzed by tetrabutylammonium fluoride (TBAF). In contrast to previously reported transformations of carbamoyl fluorides, C-F bond cleavage is achieved under exceptionally mild conditions (room temperature, low catalyst loadings, and short reaction times) without the need for strongly nucleophilic reagents and/or catalysts. This method offers distinct advantages over transition-metal-catalyzed approaches, such as tolerance to aryl halide moieties and complementary chemoselectivity.
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Affiliation(s)
- Dusty Cadwallader
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Dmytro Shevchuk
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Tristan R Tiburcio
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
| | - Christine M Le
- Department of Chemistry, York University, Toronto, Ontario M3J 1P3, Canada
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13
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Mancinelli JP, Kong WY, Guo W, Tantillo DJ, Wilkerson-Hill SM. Borane-Catalyzed C-F Bond Functionalization of gem-Difluorocyclopropenes Enables the Synthesis of Orphaned Cyclopropanes. J Am Chem Soc 2023; 145:17389-17397. [PMID: 37494703 DOI: 10.1021/jacs.3c05278] [Citation(s) in RCA: 1] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 07/28/2023]
Abstract
Herein, we disclose an approach to synthesize tert-alkyl cyclopropanes by leveraging C-F bond functionalization of gem-difluorocyclopropenes using tris(pentafluorophenyl)borane catalysis. The reaction proceeds through the intermediacy of a fluorocyclopropenium ion, which was confirmed by the isolation of [Ph2(C6D5)C3]+[(C6F5)3BF]-. We found that silylketene acetal nucleophiles were optimal reaction partners with fluorocyclopropenium ion intermediates yielding fully substituted cyclopropenes functionalized with two α-tert-alkyl centers (63-93% yield). The regioselectivity of the addition to cyclopropenium ions is controlled by their steric and electronic properties and enables access to 3,3-bis(difluoromethyl)cyclopropenes in short order. The resulting cyclopropene products are readily reduced to the corresponding orphaned cyclopropanes under hydrogenation conditions. Quantum chemical calculations reveal the nature of the C-F bond cleavage steps and provide evidence for catalysis by boron and not silylated oxonium ions, though Si-F bond formation is the enthalpic driving force for the reaction.
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Affiliation(s)
- Joseph P Mancinelli
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
| | - Wang-Yeuk Kong
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Wentao Guo
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Dean J Tantillo
- Department of Chemistry, University of California, Davis, Davis, California 95616, United States
| | - Sidney M Wilkerson-Hill
- Department of Chemistry, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States
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