A General, Regioselective Synthesis of 2-Alkenylanilines

Reduction of selected 2,1-benzothiazines with sodium amalgam leads to the formation of 2-alkenylanilines in high yield. The benzothiazines are readily available from the reaction of N-phenyl-S-(p-tolyl)sulfonimidoyl chloride with alkynes in the presence of aluminum chloride. The sulfonimidoyl chloride is derived from aniline, and the process described herein thus constitutes a high-yielding, regioselective functionalization of aniline.