Novel synthesis of 11C ‐labeled imidazolines via Pd(0)‐mediated 11C‐carbomethoxylation using [11C]CO and arylborons

[2-11C]Imidazoline-labeled [11C]FTIMD was successfully synthesized via Pd(0)-mediated11C-carbomethoxylation with [11C]CO, followed by imidazoline ring formation using EDA-AlMe3. This method was applied to several arylborons to produce [2-11C]imidazolines in low-to-moderate radiochemical yields. A labeling technique was developed for the imidazoline I2 receptor ligand 2-(3-fluoro-tolyl)-4, 5-dihydro-1H-imidazole (FTIMD) using Pd(0)-mediated11C-carbomethoxylation with [11C]CO, followed by imidazoline ring formation with ethylenediamine-trimethylaluminium (EDA-AlMe3). To achieve this, [11C]CO was passed through a methanol (MeOH) solution containing 3-fluoro-4-methylphenylboronic acid (1), palladium (II) acetate (Pd [OAc]2), triphenylphosphine (PPh3), andp-benzoquinone (PBQ). The mixture was then heated at 65 °C for 5 min. EDA was introduced into the reaction mixture, and MeOH was completely evaporated at temperatures exceeding 100°C. The dried reaction mixture was combined with an EDA-AlMe (1:1) toluene solution and heated at 145°C for 10 min. Portions of the reaction mixture were analyzed through high-performance liquid chromatography, resulting in [11C]FTIMD with 26% (n = 2) decay-corrected radiochemical yield (RCY). This method could be utilized for various arylborons to produce [2-11C]imidazolines4a–h with RCYs ranging from low to moderate. Notably, [2-11C]benazoline was obtained with a moderate RCY of 65%. The proposed technique serves as an alternative to the Gri...

Source: Journal of Labelled Compounds and Radiopharmaceuticals - November 14, 2023 Category: Biochemistry Authors: Hideki Ishii, Katsuyuki Minegishi, Kotaro Nagatsu, Nobuki Nengaki, Ming ‐Rong Zhang Tags: RESEARCH ARTICLE Source Type: research