Electrochemical Flash Fluorination and Radiofluorination

Balandeh, Mehrdad; Ríos, Alejandra; Allison, Nathanael; Shirazi, Daniela; Gomez, Adrian; Rambaran, Laura; Holloway, Travis; Sadeghi, Saman

doi:10.1002/celc.201800973

Cited by 13 publications

(6 citation statements)

References 35 publications

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“…Indeed, Sadeghi reported in 2017 the electrochemical 18 F-labelling of methyl(phenylthio)acetate under controlled potentiostatic conditions (1.4 V) using [ 18 F]TBAF in the presence of triflic acid; the process afforded methyl 2-[ 18 F]fluoro-2-(phenylthio)acetate in 7% and avoided the use of hydrogen fluoride salts (e.g. Et 3 N•3HF) (Balandeh et al 2018). In 20 18 , this methodology was improved by the use of 2,2,2-trifluoroethanol (TFE) and 2,6-di-tert-butyl-4-methylpyridine, at low temperature (-20 °C) in triflic acid (pH = 3) ( Barata-Vallejo et al 2015).…”

Section: Csp 3 -F Bond Formationmentioning

confidence: 99%

Closing the gap between 19F and 18F chemistry

Ajenjo

Destro

Cornelissen

et al. 2021

EJNMMI radiopharm. chem.

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Positron emission tomography (PET) has become an invaluable tool for drug discovery and diagnosis. The positron-emitting radionuclide fluorine-18 is frequently used in PET radiopharmaceuticals due to its advantageous characteristics; hence, methods streamlining access to 18F-labelled radiotracers can make a direct impact in medicine. For many years, access to 18F-labelled radiotracers was limited by the paucity of methodologies available, and the poor diversity of precursors amenable to 18F-incorporation. During the last two decades, 18F-radiochemistry has progressed at a fast pace with the appearance of numerous methodologies for late-stage 18F-incorporation onto complex molecules from a range of readily available precursors including those that do not require pre-functionalisation. Key to these advances is the inclusion of new activation modes to facilitate 18F-incorporation. Specifically, new advances in late-stage 19F-fluorination under transition metal catalysis, photoredox catalysis, and organocatalysis combined with the availability of novel 18F-labelled fluorination reagents have enabled the invention of novel processes for 18F-incorporation onto complex (bio)molecules. This review describes these major breakthroughs with a focus on methodologies for C–18F bond formation. This reinvigorated interest in 18F-radiochemistry that we have witnessed in recent years has made a direct impact on 19F-chemistry with many laboratories refocusing their efforts on the development of methods using nucleophilic fluoride instead of fluorination reagents derived from molecular fluorine gas.

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Section: Csp 3 -F Bond Formationmentioning

confidence: 99%

Closing the gap between 19F and 18F chemistry

Ajenjo

Destro

Cornelissen

et al. 2021

EJNMMI radiopharm. chem.

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“…Research on 18 F-labeling by electrosynthesis provides a new direction for investigations into radiofluorination ( Waldmann et al, 2017 ; Hernández-Valdés and Sadeghi, 2021 ). Professor Sadeghi’s group studied the electrochemical fluorination of di- tert -butyl-(4- tert -butyl-1,2-phenylene)-dicarbonate ( He et al, 2015 ) and methyl (phenylthio)acetate ( Balandeh et al, 2017 ; Balandeh et al, 2018 ). These studies led to the invention of an automated apparatus for 18 F-fluorination of organic molecules 16 ( Figure 4 , Reaction 6) by his group ( Waldmann et al, 2017 ), reported to achieve the highest RCY of 17.9%.…”

Section: Transition Metals Catalyzed Radiofluorinationsmentioning

confidence: 99%

Recent Advances in Synthetic Methodologies to Form C-18F Bonds

2022

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Positron emission tomography (PET) is an important technique for the early diagnosis of disease. Due to the specific physical and chemical properties of Fluorine-18, this important isotope is widely used in PET for labelling and molecular imaging, and its introduction into medicine molecules could produce PET tracers. Developing with the development of organic synthetic methodologies, the introduction of Fluorine-18 into drug molecules efficiently and rapidly under mild conditions, and the formation of C-18F chemical bonds, has become one of the leading topics in both organic synthetic chemistry and radiochemistry. In this mini-review, we review a series of recent advances in the organic synthesis of C-18F bonds (2015–2021), including non-catalytic radiofluorinations via good leaving functional groups, transition metal-catalyzed radiofluorinations, and photo- or electro-catalytic synthetic radiofluorinations. As a result of the remarkable advancements in this field, organic synthetic methods for forming C-18F bonds are expected to continue growing.

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“…9 Most electrochemical fluorinations are achieved by an umpolung strategy using oxidation of a target substrate on an anode, followed by the nucleophilic attack of fluoride ions derived from ionic liquid of HF-amine complex 10 or other fluorine sources. 11,12 Electrochemical fluorination is an environmentally friendly and safe method since neither harsh reaction conditions nor equimolar of oxidants are required. However, one inevitable drawback of the electrolysis is the use of a high concentration of supporting electrolytes (> 0.1 M), which results in a large amount of chemical waste as well as the additional steps for purification.…”

Section: Accepted M Manuscriptmentioning

confidence: 99%