Rapid Oxidation Indoles into 2‐Oxindoles Mediated by PIFA in Combination with n‐Bu4NCl ⋅ H2O

Peng, Liang; Zhao, Hang; Zhou, Tingting; Zeng, Kaiyun; Jiao, Wei; Pan, Yang; Liu, Yazhou; Fang, Dong‐Mei; Ma, Xiaofeng; Shao, Hongxia

doi:10.1002/adsc.202100234

Cited by 15 publications

(9 citation statements)

References 62 publications

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“…Finally, inspired by recent discoveries regarding the oxidation chemistry of indole heterocycles by heme-enzymes and in view to replace the highly acidic and oxidizing reagents (HCl, hypervalent halides, peroxy acids, oxone) typically employed with state-of-the-art methodologies by more sustainable and benign protocols, we applied our iron-catalyzed methodology to indole 1s (Scheme ). Under the developed reaction conditions, full conversion was observed in only 30 min and the 2-oxindole product 2s was isolated in a nonoptimized 71% yield.…”

Section: Resultsmentioning

confidence: 99%

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

et al. 2023

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Palladium-catalyzed Wacker-type reactions occupy a central place in organic synthesis with important implications in industry. Pursuing more benign protocols by replacing palladium with first-row transition metals allowed the identification of iron as a privileged one in the last few years. Although the anti-Markovnikov selectivity for iron catalysts is well developed, the Markovnikov-selective reactions still afford significant quantities of alcohol side-products, and identification of reaction intermediates has remained elusive so far. Herein, we present an iron catalyst that affords Markovnikov ketone products from (hetero)aromatic and aliphatic olefins in up to 99% selectivity under ambient conditions with 190,000 turnover numbers and turnover frequencies of 74 h −1 at 50 °C. The catalyst design is based on the promiscuous activity encountered in the family of the cytochromes P-450 enzymes, and it enables the formation of iron-hydride species under catalytically relevant reaction conditions. Substrate scope assessment and mechanistic investigations suggest that the Markovnikov-selective catalytic cycle competes with unprecedented three additional catalytic cycles (alcohol formation, hydrogenation, and reductive homo-coupling) depending on the nature of the olefin and the reaction conditions.

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Section: Resultsmentioning

confidence: 99%

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

et al. 2023

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“…In addition, 3-methyl-2-oxindoles are also accessed by various reducing 8 and oxidizing 9 protocols. Recently, a borrowing hydrogen approach has been explored by Morrill et al 10 and Venkatasubbaiah et al 11 to prepare 3-methyl-2-oxindoles using transition metal catalysts with methanol as a methylating agent.…”

Section: Introductionmentioning

confidence: 99%

Transition metal-free functionalization of 2-oxindolesviasequential aldol and reductive aldol reactions using rongalite as a C1 reagent

et al. 2022

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“…13 C{ 1 H} NMR (150 MHz, CDCl 3 ) δ 174.9, 141.2, 130.7, 126.4, 126.0, 123.6, 110.8, 52.1. All analytic data match the reported data …”

Section: Methodsmentioning

confidence: 55%

SO₂ClF: A Reagent for Controllable Chlorination and Chlorooxidation of Simple Unprotected Indoles

Zheng

Huang

2023

J. Org. Chem.

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Sulfuryl chlorofluoride was first employed as a versatile reagent for controllable chlorination and chlorooxidation of simple unprotected indoles. Three types of products including 3-chloro-indoles, 3-chloro-2-oxindoles, and 3,3-dichloro-2-oxindoles could be selectively obtained in good to excellent yields by switching the reaction solvents. The present method features easy-to-operate, broad substrate scope, and mild reaction conditions.

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Rapid Oxidation Indoles into 2‐Oxindoles Mediated by PIFA in Combination with n‐Bu₄NCl ⋅ H₂O

Cited by 15 publications

References 62 publications

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

Transition metal-free functionalization of 2-oxindolesviasequential aldol and reductive aldol reactions using rongalite as a C1 reagent

SO₂ClF: A Reagent for Controllable Chlorination and Chlorooxidation of Simple Unprotected Indoles

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Rapid Oxidation Indoles into 2‐Oxindoles Mediated by PIFA in Combination with n‐Bu4NCl ⋅ H2O

Cited by 15 publications

References 62 publications

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

Catalyst Complexity in a Highly Active and Selective Wacker-Type Markovnikov Oxidation of Olefins with a Bioinspired Iron Complex

Transition metal-free functionalization of 2-oxindolesviasequential aldol and reductive aldol reactions using rongalite as a C1 reagent

SO2ClF: A Reagent for Controllable Chlorination and Chlorooxidation of Simple Unprotected Indoles

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Rapid Oxidation Indoles into 2‐Oxindoles Mediated by PIFA in Combination with n‐Bu₄NCl ⋅ H₂O

SO₂ClF: A Reagent for Controllable Chlorination and Chlorooxidation of Simple Unprotected Indoles