Copper-Catalyzed Cascade Cyclization of Arylsulfonylhydrazones Derived from ortho-Alkynyl Arylketones: Regioselective Synthesis of Functionalized Cinnolines.

A novel copper-catalyzed cascade reaction of arylsulfonylhydrazones derived from ortho-alkynyl arylketones was accomplished. This reaction provides concise access to diversified cinnolines in good yields. The mechanistic investigations have disclosed involvement of the key alkynyl amination, 1,4-aryl migration, desulfonylation, and diazo radical cyclization cascade in the transformation.