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

摘要

We found that acetonitrile acted as a reactant under the conventional reaction conditions for aliphatic nucleophilic F-18-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 [F-18]fluoride as well as F-18-labeling enabled the preparation of F-18-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 F-18-labeled stilbene derivative as a F-18-labeled amyloid-beta ligand.