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Although various radiolabeled tryptophan analogs have been developed to monitor tryptophan metabolism using positron emission tomography (PET) for various human diseases including melanoma and other cancers, their application can be limited due to the complicated synthesis process. In this study, we demonstrated that photoredox radiofluorination represents a simple method to access novel tryptophan-based PET agents. In brief, 4-F-5-OMe-tryptophans (l/d-T) and 6-F-5-OMe-tryptophans (l/d-T) were easily synthesized. The F-labeled analogs were produced by photoredox radiofluorination with radiochemical yields ranging from 2.6 ± 0.5% to 32.4 ± 4.1% (3 ≤ ≤ 5, enantiomeric excess ≥ 99.0%) and over 98.0% radiochemical purity. Small animal imaging showed that l-[F]T achieved 9.58 ± 0.26%ID/g tumor uptake and good contrast in B16F10 tumor-bearing mice ( = 3). Clearly, l-[F]T exhibited prominent tumor uptake, warranting future evaluations of its potential usage in precise immunotherapy monitoring.
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http://dx.doi.org/10.1021/acs.jmedchem.2c01544 | DOI Listing |
Acc Chem Res
April 2025
Department of Chemistry, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 United States.
ConspectusAromatic functionalization reactions are some of the most fundamental transformations in organic chemistry and have been a mainstay of chemical synthesis for over a century. Reactions such as electrophilic and nucleophilic aromatic substitution (EAS and SAr, respectively) represent the two most fundamental reaction classes for arene elaboration and still today typify the most utilized methods for aromatic functionalization. Despite the reliable reactivity accessed by these venerable transformations, the chemical space that can be accessed by EAS and SAr reactions is inherently limited due to the electronic requirements of the substrate.
View Article and Find Full Text PDFACS Cent Sci
August 2024
Department of Radiology, Biomedical Research Imaging Center and Lineberger Comprehensive Cancer Center, University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599 United States.
To avoid the harsh conditions that are oftentimes adopted in direct radiofluorination reactions, conjugation of bioactive ligands with F-labeled prosthetic groups has become an important strategy to construct novel PET agents under mild conditions when the ligands are structurally sensitive. Prosthetic groups with [F]fluoroarene motifs are especially appealing because of their stability in physiological environments. However, their preparation can be intricate, often requiring multistep radiosynthesis with functional group conversions to prevent the decomposition of unprotected reactive prosthetic groups during the harsh radiofluorination.
View Article and Find Full Text PDFOrg Lett
May 2024
Biomedical Research Imaging Center, Department of Radiology, and UNC Lineberger Comprehensive Cancer Center, University of North Carolina-Chapel Hill, 125 Mason Farm Road, Marsico Hall, Chapel Hill, North Carolina 27599, United States.
In this study, we introduce a practical methodology for the synthesis of PET probes by seamlessly combining flow chemistry with photoredox radiofluorination. The clinical PET tracer 6-[F]FDOPA was smoothly prepared in a 24.3% non-decay-corrected yield with over 99.
View Article and Find Full Text PDFJ Am Chem Soc
May 2024
Department of Chemistry, Chemistry Research Laboratory, University of Oxford, Mansfield Road, Oxford OX1 3TA, United Kingdom.
Herein, we report a photoredox nucleophilic (radio)fluorination using TEMPO-derived alkoxyamines, a class of substrates accessible in a single step from a diversity of readily available carboxylic acids, halides, alkenes, alcohols, aldehydes, boron reagents, and C-H bonds. This mild and versatile one-electron pathway affords radiolabeled aliphatic fluorides that are typically inaccessible applying conventional nucleophilic substitution technologies due to insufficient reactivity and competitive elimination. Automation of this photoredox process is also demonstrated with a user-friendly and commercially available photoredox flow reactor and radiosynthetic platform, therefore expediting access to labeled aliphatic fluorides in high molar activity () for (pre)clinical evaluation.
View Article and Find Full Text PDFJ Med Chem
March 2023
Department of Radiology, The University of North Carolina at Chapel Hill, Chapel Hill, North Carolina 27599, United States.
Although various radiolabeled tryptophan analogs have been developed to monitor tryptophan metabolism using positron emission tomography (PET) for various human diseases including melanoma and other cancers, their application can be limited due to the complicated synthesis process. In this study, we demonstrated that photoredox radiofluorination represents a simple method to access novel tryptophan-based PET agents. In brief, 4-F-5-OMe-tryptophans (l/d-T) and 6-F-5-OMe-tryptophans (l/d-T) were easily synthesized.
View Article and Find Full Text PDF