(3+3)‐Annulation of 2‐Mercaptobenzimidazoles With α‐(Trifluoromethyl)styrene Under Ultrasonic Irradiation

A rapid and facile sonochemical route for the [3+3] annulation of 2‐mercapto benzimidazoles with α‐(trifluoromethyl)styrene was reported for the synthesis of fluorinated benzo[4,5]imidazo[2,1‑b][1,3]thiazines. The reaction proceeds through the SN2/SNV pathway while the selective SN2 pathway is completely inhibited. The developed method is effective with a wide range of substrates, tolerating diverse functional groups. The pure products are obtained with high yield (up to 92%) directly via recrystallization without column chromatography. Furthermore, applying sonochemical methodology reduces the reaction time and eliminates the need for expensive photocatalysts, ligands or oxidants.