Rapid Oxidation Indoles into 2‐Oxindoles Mediated by PIFA in Combination with <i>n</i>‐Bu<sub>4</sub>NCl ⋅ H<sub>2</sub>O
Liang Peng, Hang Zhao, Tingting Zhou, Kaiyun Zeng, Wei Jiao, Yang Pan, Yazhou Liu, Dongmei Fang, Xiaofeng Ma, Huawu Shao
Abstract
Abstract We report the development of a rapid approach for directly converting indoles into 2‐oxindoles promoted by HOCl formed in situ from the combination of (bis(trifluoroacetoxy) iodo)benzene (PIFA) and n ‐Bu 4 NCl ⋅ H 2 O. The procedure is widely functional group tolerant and provides 2‐oxindoles in up to 95% yield within 5 min. The potential applications of the developed methodology are demonstrated by the gram‐scale preparation of 3‐methyl‐2‐oxindole ( 11 a ), the one‐pot two‐step syntheses of spiro‐oxindoles 26 a and 26 b , and the formal synthesis of (‐)‐folicanthine ( 2 ). magnified image
Topics & Concepts
ChemistryOxindoleYield (engineering)BenzeneCombinatorial chemistryStereochemistryMedicinal chemistryOrganic chemistryCatalysisMetallurgyMaterials scienceOxidative Organic Chemistry ReactionsAlkaloids: synthesis and pharmacologySynthesis and Catalytic Reactions