NFSI is a new, stable and mild fluorination reagent, which can introduce fluorine atoms in the carbonyl ortho in organic molecules, and can perform monofluorination reactions on electron-rich aromatic compounds, enol silyl ethers, and lithium alcohol salts. Current research hotspots include Nazarov cyclization reaction catalyzed by iron or cobalt to form a five-membered ring, and enantioselective α-fluorination asymmetric catalysis.