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Wright JS, Ma R, Webb EW, Winton WP, Stauff J, Cheng K, Brooks AF, Sanford MS, Scott PJH. Zinc-Mediated Radiosynthesis of Unprotected Fluorine-18 Labelled α-Tertiary Amides. Angew Chem Int Ed Engl 2024; 63:e202316365. [PMID: 38010255 PMCID: PMC10872995 DOI: 10.1002/anie.202316365] [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: 10/29/2023] [Revised: 11/20/2023] [Accepted: 11/21/2023] [Indexed: 11/29/2023]
Abstract
This report describes the development of a Zn(OTf)2 -mediated method for converting α-tertiary haloamides to the corresponding fluorine-18 labelled α-tertiary fluoroamides with no-carrier-added [18 F]tetramethylammonium fluoride. 1,5,7-Triazabicyclo[4.4.0]dec-5-ene is an essential additive for achieving high radiochemical conversion. Under the optimised conditions, radiofluorination proceeds at sterically hindered tertiary sites in high radiochemical conversions, yields, and purities. This method has been successfully automated and applied to access >200 mCi (>7.4 GBq) of several model radiofluorides. Mechanistic studies led to the development of a new, nucleophilic C-H radiofluorination process using N-sulphonyloxyamide substrates.
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Affiliation(s)
- Jay S Wright
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - Richard Ma
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - E William Webb
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - Wade P Winton
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - Jenelle Stauff
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - Kevin Cheng
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - Allen F Brooks
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
| | - Melanie S Sanford
- Department of Chemistry, University of Michigan, Ann Arbor, MI-48109, USA
| | - Peter J H Scott
- Department of Radiology, University of Michigan, Ann Arbor, MI-48109, USA
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Horwitz MA, Dürr AB, Afratis K, Chen Z, Soika J, Christensen KE, Fushimi M, Paton RS, Gouverneur V. Regiodivergent Nucleophilic Fluorination under Hydrogen Bonding Catalysis: A Computational and Experimental Study. J Am Chem Soc 2023; 145:9708-9717. [PMID: 37079853 PMCID: PMC10161234 DOI: 10.1021/jacs.3c01303] [Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Indexed: 04/22/2023]
Abstract
The controlled programming of regiochemical outcomes in nucleophilic fluorination reactions with alkali metal fluoride is a problem yet to be solved. Herein, two synergistic approaches exploiting hydrogen bonding catalysis are presented. First, we demonstrate that modulating the charge density of fluoride with a hydrogen-bond donor urea catalyst directly influences the kinetic regioselectivity in the fluorination of dissymmetric aziridinium salts with aryl and ester substituents. Moreover, we report a urea-catalyzed formal dyotropic rearrangement, a thermodynamically controlled regiochemical editing process consisting of C-F bond scission followed by fluoride rebound. These findings offer a route to access enantioenriched fluoroamine regioisomers from a single chloroamine precursor, and more generally, new opportunities in regiodivergent asymmetric (bis)urea-based organocatalysis.
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Affiliation(s)
- Matthew A Horwitz
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Alexander B Dürr
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Konstantinos Afratis
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Zijun Chen
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Julia Soika
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Kirsten E Christensen
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
| | - Makoto Fushimi
- Takeda Pharmaceutical Company Limited, 26-1, Muraoka-Higashi 2-Chome, Fujisawa, Kanagawa 251-8555, Japan
| | - Robert S Paton
- Department of Chemistry, Colorado State University, Fort Collins, Colorado 80528, United States
| | - Véronique Gouverneur
- Chemistry Research Laboratory, University of Oxford, 12 Mansfield Road, Oxford OX1 3TA, U.K
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Reissig F, Mamat C. Strained Ammonium Precursors for Radiofluorinations. Chemistry 2022; 11:e202200039. [PMID: 35736542 PMCID: PMC9220932 DOI: 10.1002/open.202200039] [Citation(s) in RCA: 2] [Impact Index Per Article: 1.0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 02/21/2022] [Revised: 05/24/2022] [Indexed: 12/11/2022]
Abstract
The increasing application of positron emission tomography (PET) in nuclear medicine has stimulated the extensive development of a multitude of novel and versatile techniques to introduce fluorine‐18, especially for the radiolabelling of biologically or pharmacologically active molecules. Taking into consideration that the introduction of fluorine‐18 (t1/2=109.8 min) mostly proceeds under harsh conditions, radiolabelling of such molecules represents a challenge and is of enormous interest. Ideally, it should proceed in a regioselective manner under mild physiological conditions, in an acceptable time span, with high yields and high specific activities. Special attention has been drawn to 2‐fluoroethyl and 3‐fluoropropyl groups, which are often the active sites of radiofluorinated compounds. Precursors containing an ammonium leaving group – such as a strained azetidinium or aziridinium moiety – can help to overcome these obstacles leading to a convenient and mild introduction of [18F]fluoride with high radiochemical yields.
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Affiliation(s)
- Falco Reissig
- Institut für Radiopharmazeutische Krebsforschung Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany.,Fakultät Chemie und Lebensmittelchemie, Technische Universität Dresden, 01062, Dresden, Germany
| | - Constantin Mamat
- Institut für Radiopharmazeutische Krebsforschung Helmholtz-Zentrum Dresden-Rossendorf, Bautzner Landstraße 400, 01328, Dresden, Germany.,Fakultät Chemie und Lebensmittelchemie, Technische Universität Dresden, 01062, Dresden, Germany
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Tayama E, Kawai K. Synthesis of tertiary alkyl fluorides and chlorides by site-selective nucleophilic ring-opening reaction of α-aryl azetidinium salts. RSC Adv 2021; 11:39607-39618. [PMID: 35492462 PMCID: PMC9044468 DOI: 10.1039/d1ra08706a] [Citation(s) in RCA: 1] [Impact Index Per Article: 0.3] [Reference Citation Analysis] [Abstract] [Track Full Text] [Download PDF] [Figures] [Journal Information] [Subscribe] [Scholar Register] [Received: 11/29/2021] [Accepted: 12/03/2021] [Indexed: 12/24/2022] Open
Abstract
Site-selective nucleophilic ring-opening reactions of 2-arylazetidine-2-carboxylic acid ester-derived tetraalkyl ammonium salts 2 with tetrabutylammonium halides (Bu4NX) to give tertiary alkyl halides are successfully demonstrated. For example, a nucleophilic ring-opening reaction of 2-(o-tolyl) derivative 2a with 1.2 equivalents of tetrabutylammonium fluoride (Bu4NF) in THF at 60 °C preferentially proceeded at a more substituted carbon atom (2-position) compared to a less-substituted carbon atom (4-position) and afforded tert-butyl 4-(dimethylamino)-2-fluoro-2-(o-tolyl)butanoate 3aa in 71% yield as the corresponding tertiary alkyl fluoride. This result was applied to synthesize optically active organofluorine compounds starting from commercially available (R)-1-phenylethylamine. Site-selective nucleophilic ring-opening of 2 with Bu4NX proceeded at a much-substituted 2-position preferentially and produced tertiary alkyl halides 3.![]()
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Affiliation(s)
- Eiji Tayama
- Department of Chemistry, Faculty of Science, Niigata University Niigata 950-2181 Japan
| | - Kohei Kawai
- Graduate School of Science and Technology, Niigata University Niigata 950-2181 Japan
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