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Iridium‐Catalyzed Regio‐ and Stereoselective C‐H Oxidative Reaction to ( Z )‐3‐Arylidene‐2‐oxindole Imides under Neutral Conditions
Author(s) -
Tu Zhikai,
Tan Jie,
Chen Zhiyuan,
Tu Tao
Publication year - 2017
Publication title -
advanced synthesis and catalysis
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 1.541
H-Index - 155
eISSN - 1615-4169
pISSN - 1615-4150
DOI - 10.1002/adsc.201700983
Subject(s) - chemistry , stereoselectivity , iridium , oxindole , catalysis , pharmacophore , combinatorial chemistry , catalytic cycle , oxidative addition , cationic polymerization , medicinal chemistry , organic chemistry , stereochemistry
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.