CBr ₄ ‐Mediated Metal‐Free Sulfonamide Synthesis: A Comparative Study Under Batch, Continuous‐Flow and Ultrasonic Conditions

ABSTRACT Sulfonamides are vital scaffolds in pharmaceuticals and materials chemistry. While most oxidative sulfonamide syntheses predominantly relied iodine‐mediated protocols, bromine‐based systems remain largely unexplored. In this study, we report a CBr 4 ‐mediated oxidative coupling of sodium benzenesulfinamide with diverse primary and secondary amines under metal‐free conditions, offering an efficient and sustainable alternative to conventional approaches. The reaction proceeds smoothly under mild conditions, affording a broad range of sulfonamides in high yields with excellent functional group compatibility. Furthermore, comparative studies under batch, continuous‐flow, and ultrasound‐assisted conditions revealed that the continuous‐flow process remarkably reduced reaction time from 4 h to 15.7 min while eliminating the need for external heating and maintaining superior yields. This work not only provides a practical and efficient route to sulfonamides but also fills a significant methodological gap in halogen‐mediated oxidative coupling chemistry.