Mono- and trifluorination of the thiazole ring of 2,5-diarylthiazoles using N-fluorobenzenesulfonimide (NFSI)

Fluorination of select 2,5-diarylthiazoles using the N–F reagent N-fluorobenzenesulfonimide (NFSI) has led to the formation of both the anticipated 4-fluorothiazole as well as a unique 4,4,5-trifluorothiazole. Selective monofluorination is best achieved using bromobenzene as solvent at 155 °C, while trifluorination is best achieved by performing the reaction without solvent at 135–140 °C. An X-ray crystal structure has been obtained on one of the trifluorinated products.