Synthesis of 18F−labeled 2−cyanobenzothiazole derivative for efficient radiolabeling of N−terminal cysteine−bearing biomolecules

This article provides an efficient 18F−labeling protocol based on a rapid condensation reaction between 2−cyanobenzothiazole (CBT) and N−terminal cysteine−containing biomolecules. The 18F−labeled CBT (18F−1) was prepared by radiofluorination of the tosylated precursor 4 with 18−crown−6/K+/[18F]F− complex. Using the purified 18F−1, 18F−labeled peptide (18F−7) and protein (18F−8) could be synthesized efficiently under mild conditions. This strategy would provide a convenient approach for rapid and site−specific 18F−labeling of various peptides and proteins for in vivo imaging and biomedical applications.