Simple and efficient synthesis of 2-[ 18 F]fluoroethyl triflate for high yield 18 fluoroethylation

Open‐source flow setup for rapid and efficient [18F]fluoride drying for automation of PET tracer syntheses

“…Reactions at room temperature and without the addition of base, as well as [ 18 F]fluoroethylation of less nucleophilic starting materials, can be achieved. Peters et al developed a procedure using [ 18 F]fluoroethanol ( 8 ) as an intermediate, previously synthesized from ethylene sulfite in MeCN at 80°C 18 . After transferring the crude reaction mixture through a QMA light cartridge, the generated [ 18 F]fluoroethanol ( 8 ) was treated with triflic anhydride for 1 min at room temperature and passed through an alumina N light cartridge.…”

“…[5][6][7][8] Furthermore, shorter reaction times because of increased reaction kinetics, better control as well as adjustment of reaction conditions, which could lead to higher purity, are just some of the other major advantages. All the aforementioned properties make flow chemistry especially suitable for working with hazardous chemicals and radioactive nuclides, considering the short half-life of isotopes such as 18 F (109.77 min). 9 Because of high costs, large footprint, and limited availability and flexibility, commercial flow systems remain underutilized in radiopharmaceutical research institutes.…”

“…14 The recently published method by Pees et al describes the rapid generation of reactive [ 18 F]fluoride species for radiofluorinations without the need for azeotropic drying. 15 This technique relies on the generation of volatile [ 18 F]triflyl fluoride gas (2), which is passed through a suitable drying column and subsequently decomposed in the presence of base into nucleophilic [ 18 F]fluoride that can be used for further reactions. [ 18 F] triflyl fluoride can be obtained by the reaction of phenyl triflimide (1) with aqueous [ 18 F]Fin DMF at 50 C (Figure 1).…”

An improved radiosynthesis of O-(2-[18 F]fluoroethyl)-O-(p -nitrophenyl)methylphosphonate: A first-in-class cholinesterase PET tracer

“…Prior reports have shown that [ 18 F]-2-fluoroethanol could be prepared by reaction of n-Bu 4 N + [ 18 F]Fwith ethylene carbonate, 11 tosylate displacement with Cs 18 F, reduction of the fluoroacetic acid with an aluminum hydride 12 or Cs 18 F ring opening of ethylene sulfite. 12,13 The latter process was chosen for tracer synthesis owing to minimal steps and ease of workup. With 2-[ 18 F]fluoroethanol in hand, we envisioned a mild and facile transesterification with 2, as depicted in Scheme 1.…”

Fluorine-18 labelled building blocks for PET tracer synthesis

“…They reported a total decay-corrected radiochemical yield of 49%, which is more than twice as high as the yield reported for the one-step procedure. 60 A third approach was developed by Peters 124 Triflate building block 120 has been used in both N-alkylations and O-alkylations. 60,76,125 While O-alkylation of 121, which is the acid precursor of a potential PET tracer for the melanin concentrating hormone receptor 1, proved unsuccessful under common 60,76,124 [ 18 F]fluoroethylation conditions (the tracer could only be synthesised using direct radiofluorination in a microfluidic system), two successful N-alkylations were described (Fig.…”