Regioselective Oxidation of Pyrrole Derivatives with DDQ and Its Synthetic Application

Iwamoto, Ryoji; Ukaji, Yutaka; Inomata, Katsuhiko

doi:10.1246/cl.2010.176

Cited by 15 publications

(5 citation statements)

References 17 publications

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“…In this case the pyrrole core was not oxidized, with oxidation instead occurring at the α‐position of the alkyl substituent at the 4‐position of the pyrrole. This gave 4‐(1‐acetoxyalkyl)pyrroles when the reaction was carried out in the presence of acetic acid and 4‐acylpyrroles in the presence of methanol . Also, when glycols were used instead of methanol or acetic acid, pyrroles with hydroxyalkyl esters at the 4‐position were identified…”

Section: Oxidation Of Pyrrole With Organic Oxidantsmentioning

confidence: 95%

The Oxidation of Pyrrole

Howard

Rihak

Bissember

et al. 2015

Chemistry An Asian Journal

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The dearomatization of heterocycles has been a powerful means for producing functional molecules in synthesis. In the case of pyrroles, reductive methods (such as the Birch reduction) have been most widely exploited, while oxidative methods are generally dismissed as too difficult or unpredictable to be useful. However, since the early twentieth century considerable research has been carried out on the controlled oxidation of pyrroles to give highly functionalized products, using a variety of oxidants. This review presents a summary of all work up until the present day in the area of pyrrole oxidation, looking at the use of peroxide, singlet oxygen, hypervalent iodine reagents, a range or organic and inorganic oxidants, and electrochemical approaches. It also offers some perspective on the potential future role of pyrrole oxidation in synthesis.

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Section: Oxidation Of Pyrrole With Organic Oxidantsmentioning

confidence: 95%

The Oxidation of Pyrrole

Howard

Rihak

Bissember

et al. 2015

Chemistry An Asian Journal

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“…Deprotection of the pyrrole nitrogen atom with TBAF generates sulfonylpyrrole 6 which upon elimination of p ‐toluenesulfinic acid under basic conditions gives pyrrolenine 7 . This vinylogous‐like imino derivative is rather unstable but in the presence of a suitable nucleophile can undergo an addition reaction leading to the final product 8 7. Using this strategy several methylene active reactants (e.g., malonates, 1,3‐diketones, etc.)…”

Section: Methodsmentioning

confidence: 99%

A Keggin‐Type Structure Expanded by an Eight‐Membered Ring of Alternating Edge‐Sharing VO₅ and VO₆ Polyhedra: Solvothermal Synthesis, Crystal Structure, and Magnetic Properties

et al. 2015

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“…Herein we describe a regioselective direct oxidation of t-butyl 4 The second oxidation of 5Aa with DDQ furnished 6Aa, which was subjected to the third oxidation, followed by hydrolysis resulting in the formation of 3Aa as shown in Scheme 2 since the acetal 6Aa might be more easily oxidized by DDQ than 5Aa. Then propylene glycol ( .…”

Section: 6mentioning

confidence: 99%

“…4 The oxidative transformation of 4-methylpyrrole-2-carboxylates with DDQ and MeOH was successfully applied to the convergent synthesis of sterically locked 5Za15Ea-BV derivative.…”

mentioning

confidence: 99%

Direct Oxidation of 4-Methylpyrrole-2-Carboxylates With DDQ in the Presence of a Glycol

Takahashi¹,

Iwamoto²,

Sakata³

et al. 2012

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-Oxidation of 4-methylpyrrole-2-carboxylates with DDQ in the presence of a glycol proceeded smoothly on the methyl group at the C4 position regioselectively to afford the corresponding pyrrole-2,4-dicarboxylates directly.Direct oxidation of a methyl group of 2,4,6-trimethylphenol and 3-methyl-9H-carbazole into carboxylates was also demonstrated. (MS WordStyle "04 Het-Abstract") 2,3-Dichloro-5,6-dicyano-1,4-benzoquinone (DDQ) is a highly effective oxidant widely used in organic synthesis and its major functions include dehydrogenation, such as aromatization of hydroaromatic compounds, introduction of a double bond into carbonyl compounds, and oxidation of alcohols.Benzylic oxidation with DDQ in the presence of oxygen nucleophiles gives the corresponding oxygen-functionalized compounds. Furthermore, alternative oxidative cyclization and coupling reactions have been also reported. 1,2During our investigation on the syntheses of phytochromobilin (PΦB), phycocyanobilin (PCB), biliverdin (BV) and their analogs including sterically locked derivatives toward elucidation of the structure and function of phytochromes, 3 oxidative functionalization of pyrroles by the use of quinones was explored.In the case that DDQ was used as an oxidant, the α-position of the alkyl substituent at the C4 position was regioselectively oxidized in the presence of AcOH to afford 4-(1-acetoxyalkyl)pyrrole derivatives.In contrast, the corresponding 4-acylpyrroles were produced when MeOH was used instead of AcOH as a

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Regioselective Oxidation of Pyrrole Derivatives with DDQ and Its Synthetic Application

Cited by 15 publications

References 17 publications

The Oxidation of Pyrrole

The Oxidation of Pyrrole

A Keggin‐Type Structure Expanded by an Eight‐Membered Ring of Alternating Edge‐Sharing VO₅ and VO₆ Polyhedra: Solvothermal Synthesis, Crystal Structure, and Magnetic Properties

Direct Oxidation of 4-Methylpyrrole-2-Carboxylates With DDQ in the Presence of a Glycol

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Regioselective Oxidation of Pyrrole Derivatives with DDQ and Its Synthetic Application

Cited by 15 publications

References 17 publications

The Oxidation of Pyrrole

The Oxidation of Pyrrole

A Keggin‐Type Structure Expanded by an Eight‐Membered Ring of Alternating Edge‐Sharing VO5 and VO6 Polyhedra: Solvothermal Synthesis, Crystal Structure, and Magnetic Properties

Direct Oxidation of 4-Methylpyrrole-2-Carboxylates With DDQ in the Presence of a Glycol

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A Keggin‐Type Structure Expanded by an Eight‐Membered Ring of Alternating Edge‐Sharing VO₅ and VO₆ Polyhedra: Solvothermal Synthesis, Crystal Structure, and Magnetic Properties