5-Bromo-2-fluoropyridine (CAS number 766-11-0) is a halogenated pyridine bearing a bromine and a fluorine at 5- and 2-positions. 5-Bromo-2-fluoropyridine has been used as a molecular scaffold for many active pharmaceutical ingredients(APIs) such as inhibitors of neuropeptide Y receptor Y5, inhibitors of the main protease of SARS-CoV-2 and inhibitors of indoleamine-2,3-dioxygenase-1 in cancer immunotherapy. The bromine and fluorine substituents have different reactivity. Fluorine substituent is in favor of nucleophilic aromatic substitution, while bromine substituent prefers copper/palladium catalyzed C-C/C-N coupling.
5-Bromo-2-fluoropyridine is also an ideal building block for semiconductors, due to its aromaticity and electron deficiency. A host material of 5-(5-(2,4,6-triiso-propylphenyl)pyridin-2-yl)-5H-benzo[d]benzo-[4,5]imidazo[1,2-a]imidazole is synthesized from 5-bromo-2-fluoropyridine for OLED applications.