N-Alkyl 3-aminobut-2-enenitrile as a Non-radioactive Side Product in Nucleophilic 18 F-Fluorination

摘要

We found that acetonitrile acted as a reactant under the conventional reaction conditions for aliphatic nucleophilic 18 F- fluorination in acetonitrile to provide the N-alkyl 3-aminobut-2- enenitrile as one of the side products. Dimerization of acetonitrile promoted by a complex of K2CO3 and K222 provided 3-aminobut-2-enenitrile, which acted as nucleophile to provide N-alkyl amino derivatives. Based on the finding, avoiding acetonitrile in the drying of [ 18 F]fluoride as well as 18 F- labeling enabled the preparation of 18 F-labeled compounds containing only a small amount of the corresponding alcohol. Finally, we used an automated synthesizer to achieve an efficient phase-tag-assisted synthesis of 18 F-labeled stilbene derivative as a 18 F-labeled amyloid-β ligand.