Recent Advances in ¹⁸F Radiochemistry: A Focus on B-¹⁸F, Si-¹⁸F, Al-¹⁸F, and C-¹⁸F Radiofluorination via Spirocyclic Iodonium Ylides

Abstract

Straightforward radiosynthesis protocols for F-labeled radiopharmaceuticals are an indispensable but often overlooked prerequisite to successfully perform molecular imaging studies in vivo by PET. In recent years, thanks to the expansion of theF chemical toolbox, structurally diverse and novel clinically relevant radiopharmaceuticals have been synthesized with both high efficiency and ready implementation. This article provides an overview of recent F-labeling methodologies, specifically for B-F, Si-F, Al-F, and iodine (III)-mediated radiofluorination via the spirocyclic iodonium ylide technology.

A review of approaches to 18F radiolabelling affinity peptides and proteins

“…Two types of 18 F acceptor chemistry used to radiolabel APPs will be discussed: ([ 18 F]AlF) 2+ complexation and isotopic exchange. The authors refer readers to a recent review of recent 18 F radiochemistry advances, which includes 18 F acceptor approaches and also a review of ([ 18 F]AlF) 2+ coordination chemistries by Kumar et al…”

“…([ 18 F]AlF) 2+ has been used to radiolabel a number of APPs in a 1‐pot, high yielding reaction characterised by Al chelation followed by the formation of a strong Al‐F bond, first reported by McBride et al…”

“…Two types of 18 F acceptor chemistry used to radiolabel APPs will be discussed: ([ 18 F]AlF) 2+ complexation and isotopic exchange. The authors refer readers to a recent review of recent 18 F radiochemistry advances, which includes 18 F acceptor approaches 58 and also a review of ([ 18 F] AlF) 2+ coordination chemistries by Kumar et al 59 2+ has been used to radiolabel a number of APPs in a 1-pot, high yielding reaction characterised by Al chelation followed by the formation of a strong Al-F bond, first reported by McBride et al 58,69,70 Da Pieve et al 57 used the ([ 18 F]AlF) 2+ method to radiolabel a HER3-specific affibody with a view to assessing its usefulness as radiotracer in oncology; the method mirrored conditions reported by Glaser et al 72 The affibody was derivatised with 1,4,7triazacyclononane-1,4,7-triacetic acid (NOTA) and incubated with AlCl 3 . Final incubation of the complex with 18 F gave rise to yields of 38.8 ± 5.8% non-decay-corrected (n.d.c) and molar activity measurements of 6.0 to 11.9 GBq/μmol were reported.…”

[18F]Ethenesulfonyl Fluoride as a Practical Radiofluoride Relay Reagent

“…Herein, we describe the use of [ 18 F]ethenesulfonyl fluoride(ESF) as an ovel radiofluorider elay reagent that allowsr adiofluorination reactions to be performedi nm inimally equipped satelliten uclear medicine centres. [6][7][8] To achieves uch an important target, we focusedo nf luoride relay reagents, [9] where reactive fluorides peciesc an be releasedf ollowing simple chemical or physical interaction. The cartridges can then be shipped remotely and the trapped [ 18 F]ESF can be liberated by simple solvent elution.…”

“…[3] On the other hand, in most nuclear medicine departments where 99m Tc is used, "shake&b ake" labelling reactions are performed using minimal equipment, [4] thus providing access to aw ide array of 99m Tc radiotracers. [6][7][8] To achieves uch an important target, we focusedo nf luoride relay reagents, [9] where reactive fluorides peciesc an be releasedf ollowing simple chemical or physical interaction. [6][7][8] To achieves uch an important target, we focusedo nf luoride relay reagents, [9] where reactive fluorides peciesc an be releasedf ollowing simple chemical or physical interaction.…”