Development of an Efficient Synthetic Process for Broflanilide

This article describes the development of an efficient and scalable synthetic route to the novel insecticide broflanilide (1). This redesigned synthetic sequence starts from 2-fluoro-3-nitrobenzoic acid and 4-(perfluoropropan-2-yl)-2-(trifluoromethyl) aniline and provides the target product in a high overall yield through condensation, nitro group reduction, N-methylation, amidation, and subsequent bromination steps. The desired amide moiety is established under mild conditions, and imide generation is avoided. Using paraformaldehyde and Pt/C for N-methylation and NaBr-NaClO for bromination increased the industrial suitability of this route. Unlike existing routes, this new route requires isolation at only six steps (including the heptafluorination), and the overall yield was 60.3%, representing a significant improvement. Broflanilide (1) crystals were obtained from recrystallization in 98% aqueous CH3OH, and the structure was confirmed by X-ray analysis. This work provides a reliable strategy for the large-scale manufacturing of broflanilide (1).