Iron-catalyzed C–N bond formation via oxidative Csp3–H bond functionalization adjacent to nitrogen in amides and anilines: Synthesis of N-alkyl and N-benzyl azoles

Saidulu, G.; Kumar, Rakesh; Reddy, K. Rajender

doi:10.1016/j.tetlet.2015.05.048

Cited by 23 publications

(10 citation statements)

References 68 publications

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“…The reaction mechanism of the oxidative C−N coupling, even in homogeneous phase, has not been yet disclosed . To gain insight on the reaction mechanism, a series of control experiments were performed in the presence of 2,2,6,6‐tetramethylpiperidyl‐1‐oxyl (TEMPO) as a quencher of possible C‐centered radical intermediates.…”

Section: Resultsmentioning

confidence: 68%

“…Initially, 1,2‐dichloroethane (DCE) was used as a solvent because literature data suggested that this could be one of the most suitable solvents for the reaction . However, in contrast to the report in the literature, under our reaction conditions the C−N coupling product ( 3 a ) was observed as a primary, but instable product, undergoing a subsequent conversion to N ‐(2‐chloroethyl)benzimidazole ( 3 b ) as final and stable product. A time–conversion plot of the catalytic oxidative C−N coupling using DCE as a solvent is shown in Figure .…”

Section: Resultsmentioning

confidence: 99%

“…The catalytic activity of these MNP@C samples for the oxidative C−N cross coupling of aromatic N−H compounds and amides has been determined and details of the reaction mechanism involving radicals unveiled. Related precedents have reported the oxidative C−N coupling of aromatic N−H compounds with amides using di‐ tert ‐butyl peroxide as oxidizing agent and homogeneous Fe 2+ catalysts as well as a Cu metal organic framework as heterogeneous catalyst . However, MNPs wrapped in graphitic carbon, which are currently under intense investigation because of their unique catalytic activity that has frequently been observed, have not yet been reported as catalysts for this reaction.…”

Section: Introductionmentioning

confidence: 99%

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Iron Nanoparticles Embedded in Graphitic Carbon Matrix as Heterogeneous Catalysts for the Oxidative C−N Coupling of Aromatic N−H Compounds and Amides

Dhakshinamoorthy

Primo

et al. 2017

ChemCatChem

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Fe or Co nanoparticles (NPs) and two nanoparticulate Fe‐Co alloys having different Fe/Co atomic ratio with average particle size ranging from 10.9 to 26.5 nm embedded in turbostratic graphitic carbon matrix have been prepared by pyrolysis at 900 °C under inert atmosphere of chitosan powders containing Fe2+ and Co2+ ions in various proportions. The resulting Fe/Co NP@C samples have been evaluated as heterogeneous catalysts for the oxidative C−N coupling of amides and aromatic N−H compounds. It was observed that sequential addition of two aliquots of tert‐butyl hydroperoxide (TBHP) in an excess of N,N‐dimethylacetamide (DMA) as solvent affords the corresponding coupling product in high yields, and the most efficient catalyst was Fe NP@C. Fe NP@C is reusable and exhibits a wide scope. The catalytic activity of Fe is supported by using highly pure Fe salt and by the observation that purposely addition of Cu2+ impurities even plays a detrimental effect on the catalytic activity. Mechanistic studies by quenching with 2,2,6,6‐tetramethylpiperidyl‐1‐oxyl (TEMPO) have shown that the amide radical is the key reaction intermediate, and the role of Fe NP@C is to generate the first radicals by TBHP decomposition.

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Section: Resultsmentioning

confidence: 68%

Section: Resultsmentioning

confidence: 99%

Section: Introductionmentioning

confidence: 99%

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Iron Nanoparticles Embedded in Graphitic Carbon Matrix as Heterogeneous Catalysts for the Oxidative C−N Coupling of Aromatic N−H Compounds and Amides

Dhakshinamoorthy

Primo

et al. 2017

ChemCatChem

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“… A metallophotoredox catalysis of C−H functionalization ( A ) and tert‐butyl hydroperoxide radical based couplings toward morpholine functionalization ( B – D ). Reagents and conditions : a) Ni(dtbbpy)Br 2 (5 mol %), TBADT (1 mol %), K 3 PO 4 (1.1 equiv), ACN (0.1 M), 34 W 390 nm Kessil lamp, fan (yield: 48 %); b) TBHP (2 equiv), t ‐BuOK (10 mol %), MeCN, 110 °C, 24 h (yield: 44 %); c) TBHP (1.5 equiv), FeSO 4 ⋅ 7H 2 O (20 mol %), rt, 36 h (yield: 51 %); d) TBHP (10 mol %), Fe(OAc) 2 (10 mol %), DCE, N 2 atm, 80 °C, 3 h (yield: 51 %) . (TBADT: tetrabutylammonium decatungstate)…”

Section: Synthesis Of Morpholinesmentioning

confidence: 99%

“…An alternative approach to these radical based couplings is utilizing radicals produced through tert‐butyl hydroperoxide (TBHP) (Scheme B−D). TBHP decomposition is mediated by either potassium tert‐butoxide (Scheme B) or an iron catalyst (Scheme C and D) . It should be noted that reactions B and D (Scheme ) require the use of 10 equivalents of the starting morpholine to proceed and the yield is based on the coupling partner, imposing limitations to their broader use.…”

Section: Synthesis Of Morpholinesmentioning

confidence: 99%

Morpholine As a Scaffold in Medicinal Chemistry: An Update on Synthetic Strategies

2020

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Morpholine is a frequently used heterocycle in medicinal chemistry and a privileged structural component of bioactive molecules. This is mainly due to its contribution to a plethora of biological activities as well as to an improved pharmacokinetic profile of such bioactive molecules. The synthesis of morpholines is a subject of much study due to their biological and pharmacological importance, with the last such review being published in 2013. Here, an overview of the main approaches toward morpholine synthesis or functionalization is presented, emphasizing on novel work which has not been reviewed so far. This review is an update on synthetic strategies leading to easily accessible libraries of bioactives which are of interest for drug discovery projects.

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Iron Catalyzed Oxidative Coupling, Addition, and Functionalization

et al. 2016

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We cover the achievements and thought process that have emerged as a result of the recent use of iron salts as catalysts for the oxidative coupling, addition, and functionalization on constructing C−C bonds, C−N bonds, C−O bonds, C−S bonds, and C−P bonds. These transformations concomitantly require a stoichiometric oxidant to activate the catalyst: The low‐cost and ubiquity of peroxides is often used as a result of their high oxidative reactivity, resulting in the widespread utilizations of iron catalysis through the initiation of radical processes. Here, we summarize the formation of diverse chemical bonds by using iron oxidative catalysis strategies, including 1) the oxidative coupling strategy and 2) the oxidative addition and functionalization strategy. The oxidative coupling strategy focuses on the formation of one chemical bond in a single reaction, whereas the oxidative addition and functionalization strategy includes the transformations that construct at least two chemical bonds.

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Iron-catalyzed C–N bond formation via oxidative Csp3–H bond functionalization adjacent to nitrogen in amides and anilines: Synthesis of N-alkyl and N-benzyl azoles

Cited by 23 publications

References 68 publications

Iron Nanoparticles Embedded in Graphitic Carbon Matrix as Heterogeneous Catalysts for the Oxidative C−N Coupling of Aromatic N−H Compounds and Amides

Iron Nanoparticles Embedded in Graphitic Carbon Matrix as Heterogeneous Catalysts for the Oxidative C−N Coupling of Aromatic N−H Compounds and Amides

Morpholine As a Scaffold in Medicinal Chemistry: An Update on Synthetic Strategies

Iron Catalyzed Oxidative Coupling, Addition, and Functionalization

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