Tungstate-catalyzed oxidation of tetrahydroquinolines with hydrogen peroxide: A novel method for the synthesis of cyclic hydroxamic acids

Murahashi, Shun‐Ichi; Oda, Tetsuya; Sugahara, Toshiaki; Masui, Yoshiyuki

doi:10.1021/jo00293a014

Cited by 75 publications

(21 citation statements)

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“…Functionalization of the sp 3 C–H bond α to the nitrogen atom in tetrahydroquinolines and indolines via iminium ions is challenging because the corresponding iminium ions are enolizable and thus tend to tautomerize to enamines [94–95] and/or aromatize [96–97]. The authors adopted a strategy to bypass the iminium ions and use α-amino radicals such as 112 instead to construct C–N bonds.…”

Section: Reviewmentioning

confidence: 99%

The chemistry of amine radical cations produced by visible light photoredox catalysis

Hu¹,

Wang²,

Nguyen³

et al. 2013

Beilstein J. Org. Chem.

382

228

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Amine radical cations are highly useful reactive intermediates in amine synthesis. They have displayed several modes of reactivity leading to some highly sought-after synthetic intermediates including iminium ions, α-amino radicals, and distonic ions. One appealing method to access amine radical cations is through one-electron oxidation of the corresponding amines under visible light photoredox conditions. This approach and subsequent chemistries are emerging as a powerful tool in amine synthesis. This article reviews synthetic applications of amine radical cations produced by visible light photocatalysis.1977

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Section: Reviewmentioning

confidence: 99%

The chemistry of amine radical cations produced by visible light photoredox catalysis

Hu¹,

Wang²,

Nguyen³

et al. 2013

Beilstein J. Org. Chem.

382

228

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“…Oxidation of Amines Catalyzed by PWAA Since PWAA efficiently promoted the epoxidation of allylic alcohols, we applied this oxidation system to secondary amines. [45][46][47][48][49][50][51][52][53][54][55][56] Oxidation of secondary amines is the most straightforward method and the direct route to prepare nitrones, which are important substrates for the synthesis of nitrogen-containing bioactive compounds. It was beforehand confirmed that no oxidation of dibenzylamine (11a) with hydrogen peroxide was observed at room temperature.…”

Section: Epoxidation Of Allylic Alcoholsmentioning

confidence: 99%

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

Yamada

2005

CHEMICAL & PHARMACEUTICAL BULLETIN

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IntroductionDevelopment of immobilized and insoluble metal catalysts is of great interest in recent organic chemistry. [1][2][3][4][5][6][7][8][9] The simple recovery of catalysts by filtration and their reuses resulted in enhancing the economical evaluation of the reaction. At the same time, there is a prospect that the environmental pollution caused by residual metals in the waste fluid will be decreased. Although a great deal of effort has been made to carry out such ideal reactions using immobilized metal catalysts, what seems to be lacking is the efficiency of the catalytic systems. It is obvious that the heterogeneous catalytic systems exhibit generally lower activity than the homogeneous ones. Besides, it is expected that the activity of the catalysts decreases gradually in the recycled systems because the metal species leaches away from their supports. Taking these into consideration, we decided to concentrate on developing insoluble metal catalysts which are highly active and stable. We designed that they were still effective in the use of ppm mol eq, and in the recycled use of many times in any reaction media. To achieve the challenging theme, we have focused on the amphiphilic insoluble catalysts based on a novel concept (Chart 1).Over the past few decades, a considerable numbers of study have been made on solid-phase catalysts which were immobilized with cross-linked polystyrene resins, silica gels or metals. These catalytic systems, however, generally resulted in lower catalytic activity compared with their soluble counterparts, and were often obliged to use hazardous chlorohydrocarbon solvents. [10][11][12][13][14][15] Besides, reuse of these catalysts was often difficult owing to the gradual decline of the catalytic activity. These problems made them less practical.In traditional triphase catalysts, as I have mentioned before, a catalytic species was anchored to a linker that was immobilized to a polymer resin or silica gel (Chart 1, above). In July 2005Chem. Pharm. Bull. 53(7) 723-739 (2005)

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“…Similarly, when benzylamine 9a was reacted under our optimised conditions, no hydroisoquinoline was evidenced by 1 H NMR, only partial conversion into its oxidised analogue, isoquinoline 10a (Table , entry 9). While we could not find precedents with copper for this transformation in the literature, we would expect the metal to be involved in this aerobic aromatisation of the intermediate 1,2‐dihydroisoquinoline …”

Section: Resultsmentioning

confidence: 84%

A Commercially Available and User‐Friendly Catalyst for Hydroamination Reactions under Technical Conditions

et al. 2019

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Tungstate-catalyzed oxidation of tetrahydroquinolines with hydrogen peroxide: A novel method for the synthesis of cyclic hydroxamic acids

Cited by 75 publications

References 1 publication

The chemistry of amine radical cations produced by visible light photoredox catalysis

The chemistry of amine radical cations produced by visible light photoredox catalysis

Self-Assembled Complexes of Non-cross-linked Amphiphilic Polymeric Ligands with Inorganic Species: Highly Active and Reusable Solid-Phase Polymeric Catalysts

A Commercially Available and User‐Friendly Catalyst for Hydroamination Reactions under Technical Conditions

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