N.C.A. [¹⁸F]‐labelling of aliphatic compounds in high yields via aminopolyether ‐ supported nucleophilic substitution

Abstract

The nucleophilic introduction of n.c.a. ‐ [18F]‐fluoride into alkanes and carboxylic acids using anion activation by macrocyclic polyethers was investigated. The reactions carried out in the presence of the bicyclic aminopolyether APE 2.2.2. gave rise to high radiochemical yields (40‐65 %) under mild conditions. Important for the successful 18F‐labelling is a suitable cation/polyether couple, which leads to an unsolvated [18F]‐fluoride in a dipolar aprotic solvent and ensures a high ion concentration, thus enhancing the reactivity. Reaction parameters, such as concentration of substrate and APE, the influence of cation, anion and water were studied and optimised.

A one‐step automated synthesis of the dopamine transporter ligand [18F]FECNT from the chlorinated precursor

“…Major loss of [ 18 F]FECNT radioactivity was noted in the reactor vessel and during the automated injection of the reaction mixture into the HPLC injection loop. The loss of radioactivity in the reactor was probably due to presence of undissolved K[ 18 F]F‐Kryptofix®222 complex, which was also reported in literature . This loss was partially reduced during the optimization process of [ 18 F]FECNT radiosynthesis by stirring the reactor contents and by increasing the volume of precursor solution from 1 to 2 mL.…”

Procedures for the GMP-Compliant Production and Quality Control of [18F]PSMA-1007: A Next Generation Radiofluorinated Tracer for the Detection of Prostate Cancer

“…The green trail (activity in Reaction Vessel 1) shows some noisy behaviour during the drying process, which is caused by the changes of the activity per volume in Vessel 1 occurring throughout the process (geometric factors). About 20% of the radioactivity is left in Reaction Vessel 1 after labelling and extraction of the mixture, which is a behaviour for no carrier added [ 18 F]F − typically observable in glass reaction vessels [ 28 ]. Roughly 30% of the activity from Reaction Vessel 1 is then trapped on the MCX cartridge (purple line).…”

Radiosynthesis and Radiotracer Properties of a 7-(2-[18F]Fluoroethoxy)-6-methoxypyrrolidinylquinazoline for Imaging of Phosphodiesterase 10A with PET

“…[ 18 F]fluoride solution (1–2 mL) was added to 4,7,13,16,21,24-hexaoxa-1,10-diazabicyclo-[8.8.8]hexacosane (Kryptofix ® , K2.2.2, 11.20 mg, 0.03 mmol), 0.15 M aqueous K 2 CO 3 solution (89 μL, 0.013 mmol) and acetonitrile (1 mL) in a 10 mL conical vessel, equipped with magnetic stirrer, septum, as well as vacuum and inert gas access. This mixture was azeotropically dried according to previously described protocols [41,42], resulting in the K[ 18 F]F-K2.2.2-carbonate complex, dissolved in anhydrous acetonitrile (1 mL). With 500 μL of the light yellow solution, nucleophilic substitution was performed in a 5 mL conical vessel under inert gas by reacting ethane-1,2-diyl bis(4-methylbenzenesulfonate) II (2.0 mg, 0.005 mmol, Scheme 1) under stirring at 80 °C, using a heating block.…”