Iridium‐Catalyzed Regio‐ and Stereoselective C‐H Oxidative Reaction to (<i>Z</i>)‐3‐Arylidene‐2‐oxindole Imides under Neutral Conditions

Abstract

Abstract Unsymmetrical 3‐arylidene‐2‐oxindoles are useful pharmacophores for many clinical drugs or intermediates in alkaloids synthesis. An Iridium III ‐catalyzed sequential C−H oxidative reaction of 2‐indolyl enamides has been established. This protocol utilized α,α ‐dimethyl benzylhydroperoxide as the oxidant and silver fluoride as a key promoter, to provide a wide range of ( Z )‐3‐arylidene‐2‐oxindole imides in moderate to good yields, together with good regio‐ and stereoselectivity. The silver fluoride was found to function as a base to facilitate the generation of the active Iridium catalyst species. The resulting ( Z )‐3‐arylidene‐2‐oxindole imides could be further transformed to various valuable derivatives. Mechanistically, radical‐process was excluded from this C−H oxidative transformation, and a 6‐membered cationic iridacycle intermediate was proposed to be involved in the catalytic cycle. magnified image