Recent Developments and Trends in 18F-Radiochemistry: Syntheses and Applications

Abstract

In this short review we describe recent methods and novel trends for the introduction of fluorine-18 into molecules which in turn are intended to serve as imaging agents for the in vivo imaging modality positron emission tomography (PET). These 18 F-labeling schemes are based on enzymatic fluorination, the use of ionic liquids, protic solvents acting as catalysts, application of "click chemistry", thiol-reactive labeling agents for peptide and protein labeling and the most recent introduction of "non-classical" radiochemistry based on organo-phosphorous, organo-boron and organo-silicon radiochemistry. The latter approach for the first time introduced an 18 F-chemistry characterized by high selectivity and unique efficiency making complicated work-up procedures obsolete.

Copper-Free Click for PET: Rapid 1,3-Dipolar Cycloadditions with a Fluorine-18 Cyclooctyne

“…27 In light of these characteristics and, in particular, the short half-life (T 1/2 = 110 min), simple, fast, and efficient reactions are needed. In addition to offering fast reaction kinetics, cyclooctynes, possessing ∼18 kcal/mol of strain energy, 28 react with terminal azides without the need for cytotoxic copper salts and are thus well suited for reactions in biological settings.…”

Synthesis of new 18F-radiolabeled silicon-based nitroimidazole compounds

“…At 37°C in plasma, half-lives of both compounds were below 5 min. We then refocused our efforts to the SiFA (Silicon-fluoride-acceptor) compounds developed by Schirrmacher et al [6][7][8][16][17][18][19][20][21][22][23] In this case, silicon is substituted by a phenyl and two t-butyl groups.…”

Silicon-[18F]Fluorine Radiochemistry: Basics, Applications and Challenges

“…The introduction of Si- 18 F [5][6][7], B- 18 F [5,6] and Al- 18 F [8][9][10][11][12] radiochemistry has set the foundation for the development of novel radiotracers and has the potential to reshape the landscape of 18 F-radiochemistry if some hurdles can be overcome in time. This review article deals primarily with Si- 18 F radiochemistry and the interested reader is advised to further consult various excellent review articles on 18 F-radiochemistry [13][14][15][16][17][18] and original publications about B- 18 F and Al- 18 F chemistry.…”