Metal‐Free and Scalable Borane‐Catalyzed Dehydrative C–N Coupling of Allylic Alcohols and Sulfonamides

This study reports a metal‐free and atom‐economical allylation strategy that embodies multiple principles of green chemistry. Specifically, this transformation is achieved using a commercially available and air‐stable borane catalyst, B(C ₆ F ₅ ) ₃ . This represents the first example of boron‐catalyzed direct N‐allylation of sulfonamides with allylic alcohols, generating water as the sole byproduct. The operationally simple reaction proceeds without calling for stringent removal of air and moisture, and can be readily scaled up to gram scale. Preliminary mechanistic studies confirm the generation of allylic carbocation within the catalytic cycle, whereas in situ formed diallyl ether acts as an off‐cycle reservoir species instead of a key on‐cycle intermediate. This protocol provides a sustainable and practical alternative for the synthesis of N‐allylic sulfonamide intermediates, avoiding metal residue concerns in pharmaceutical manufacturing.