Transition-Metal-Catalyzed Cleavage of C–N Single Bonds

Ouyang, Kunfu; Wei, Hao; Zhang, Wen‐Xiong; Xi, Zhenfeng

doi:10.1021/acs.chemrev.5b00386

Cited by 571 publications

(318 citation statements)

References 347 publications

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“…7 The disruption of this conjugation by steric effects that increase the nonplanarity about the C–N amide bond or the delocalization of the lone pair of electrons on the nitrogen by electron-withdrawing groups results in a lower barrier for the formation of the acylmetal intermediate. 6 Although significant advances have taken place in transition-metal-catalyzed cross-couplings of amides with aryl boronic acids, alkylation reactions have been restricted to the use of Weinreb amides with highly reactive organometallic nucleophiles 8 and minimally functionalized alkylzinc reagents 9 in transition-metal-catalyzed transformations.…”

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confidence: 99%

Synergistic Visible-Light Photoredox/Nickel-Catalyzed Synthesis of Aliphatic Ketones via N–C Cleavage of Imides

et al. 2017

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An electrophilic, imide-based, visible-light-promoted photoredox/Ni-catalyzed cross-coupling reaction for the synthesis of aliphatic ketones has been developed. This protocol proceeds through N–C(O) bond activation, made possible through the lower activation energy for metal insertion into this bond due to delocalization of the lone pair of electrons on the nitrogen by electron-withdrawing groups. The operationally simple and mild cross-coupling reaction is performed at ambient temperature and exhibits tolerance for a variety of functional groups.

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confidence: 99%

Synergistic Visible-Light Photoredox/Nickel-Catalyzed Synthesis of Aliphatic Ketones via N–C Cleavage of Imides

et al. 2017

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“…There are examples of metal-catalyzed functionalization of pyridines in the para position, [13] but to our knowledge this is the first example of C-N cleavage in DMAP. C-N cleavage is a difficult reaction with numerous potential catalytic applications, [14] and so the observation of roomtemperature C(aryl)-N cleavage is particularly interesting. [3e, 15] The C-H and C-N activation products from reactions of LFe(C 6 H 6 ) with pyridine, tertbutylpyridine, and DMAP can be explained using a mechanistic scaffold (Scheme 4) that conceptually derives from the previously reported reaction of LFe(C 6 H 6 ) with 1 equiv of pyridine to give LFe(py)(μ-κ 1 :η 3 -py)FeL (7; downward in Scheme 4).…”

Section: Author Manuscriptmentioning

confidence: 99%

C−H and C−N Activation at Redox‐Active Pyridine Complexes of Iron

et al. 2016

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Pyridine activation by inexpensive iron catalysts has great utility, but the steps through which iron species can break the strong (105-111 kcal/mol) C-H bonds of pyridine substrates are unknown. In this work, we report the rapid room-temperature cleavage of C-H bonds in pyridine, 4-tertbutylpyridine, and 2-phenylpyridine by an iron(I) species, to give well-characterized iron(II) products. In addition, 4-dimethylaminopyridine (DMAP) undergoes room-temperature C-N bond cleavage, which forms a dimethylamidoiron(II) complex and a pyridyl-bridged tetrairon(II) square. These facile bond-cleaving reactions are proposed to occur through intermediates having a twoelectron reduced pyridine that bridges two iron centers. Thus, the redox non-innocence of the pyridine can play a key role in enabling high regioselectivity for difficult reactions. Graphical abstractAn iron(I) complex can activate C-H and C-N bonds in pyridines, using a mechanism that takes advantage of pyridine's redox activity. KeywordsPyridine; Iron; Redox-Active; Bond Cleavage Pyridines are widespread in pharmaceuticals, natural products, and polymers, and therefore their expedient synthesis is crucial. [1] However, pyridines are relatively unreactive in the absence of prior activation. [2] Direct cleavage of C-H bonds in unfunctionalized pyridines is uncommon, but has made substantial progress recently. [3] A recent exciting development has been the C-H arylation of pyridines using catalytic mixtures generated in situ from simple iron salts and an excess of Grignard reagent. [4] This recipe presumably generates reduced Correspondence to: Patrick L. Holland. a These authors contributed to this work equally, and should be considered co-first authors.Supporting information for this article can be found under: http://dx.doi.org/10.1002/anie.XXXX HHS Public Access Author ManuscriptAuthor Manuscript Author ManuscriptAuthor Manuscript iron species that are the catalysts, but little is known about reduced iron-pyridine compounds and what stoichiometric steps to expect under these conditions. In this communication, we report well-characterized iron products that result from pyridine C-H bond cleavage. We also show an unprecedented C-N bond cleavage of 4-dimethylaminopyridine (DMAP) and construct a reasonable mechanistic scaffold that is based on the ability of pyridines to accept charge from low-valent iron.Pyridines are well-known redox-active ligands. [5] We have shown that the addition of one or more equiv of pyridine to the iron(I) complex LFe(C 6 H 6 ) (L = β-diketiminate ligand, shown in Scheme 1) yields products in which the pyridine ligands are reduced by 1-2 electrons. [6] However, we have now discovered that addition of smaller amounts of pyridine leads to formation of a surprising new compound (1). Solutions of 1 are in equilibrium with the previously characterized pyridine-bound complexes and with LFe(C 6 H 6 ), as shown by 1 H NMR spectra of C 6 D 6 solutions of 1 with various amounts of pyridine ( Figure S5). Compound 1 can be isolated by...

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“…The formation and transformation of C−N bond are among the central topics in organic chemistry, organometallic chemistry, and biochemistry. 15 The C-N bond is strong in organic molecules, thus, the transformations via C-N bond cleavage are usually difficult. 16 Recently, transition-metal-catalyzed decarboxylative coupling reactions have generated much interest because of its efficiency, selectivity, as well as convenience (Scheme 1), 17 Very recently, decarbonylation/dehydration reactions also have been studied and constitute a useful tool in synthesis of olefins 18 Despite the significant advances in decarbonylation reactions, questions concerning decarbonylation/dehydration of amino acids was less explored.…”

Section: Introductionmentioning

confidence: 99%

Cu(Ⅱ)-promoted oxidative C-N bond cleavage of N-benzoylamino acids to primary aryl amides

Zhou¹,

Liu²,

Zhao³

et al. 2016

Arkivoc

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A novel protocol for CuCl2-promoted oxidative C-N bond cleavage of N-benzoyl amino acids was developed. It is the first example of using accessible amino acid as an ammonia synthetic equivalent for the synthesis of primary aryl amides via CuCl2-promoted oxidative C-N bond cleavage reaction. The present protocol shows excellent functional group tolerance and provides an alternative method for the synthetic of primary aryl amides in 84-96% yields.

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Transition-Metal-Catalyzed Cleavage of C–N Single Bonds

Cited by 571 publications

References 347 publications

Synergistic Visible-Light Photoredox/Nickel-Catalyzed Synthesis of Aliphatic Ketones via N–C Cleavage of Imides

Synergistic Visible-Light Photoredox/Nickel-Catalyzed Synthesis of Aliphatic Ketones via N–C Cleavage of Imides

C−H and C−N Activation at Redox‐Active Pyridine Complexes of Iron

Cu(Ⅱ)-promoted oxidative C-N bond cleavage of N-benzoylamino acids to primary aryl amides

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