An Efficient Heterobimetallic Lanthanide Alkoxide Catalyst for Transamidation of Amides under Solvent‐Free Conditions

Sheng, Hongting; Zeng, Ruijie; Wang, Wenjuan; Luo, Shuwen; Feng, Yan; Liu, Jing; Chen, Weijian; Zhu, Manzhou; Guo, Qi

doi:10.1002/adsc.201600373

Cited by 38 publications

(8 citation statements)

References 125 publications

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“…Taking advantage of the insertion of such catalysts into the C-N bond, the groups of Garg 143,144 and Hu 145 in the case of nickel-catalysis, and Szostak in the case of palladium catalysis, 146 have introduced a variety of transamidation protocols with primary and secondary amines (Scheme 39a). Other metals have also been employed in isolated cases: in this regard, lanthanide catalysts have been shown to activate primary amides for transamidation reactions with a range of amines (Scheme 39b, top), 147 and-mimicking biological systems-especially tailored nicotinate amides can be alcoholised using zinc catalysis (Scheme 39b, bottom). 148 Remarkably, in 2017, Szostak and co-workers reported a transamidation reaction that proceeds even in the absence of a transition metal catalyst, exploiting the increased electrophilicity of non-planar amides.…”

Section: Smi 2 -Mediated Functionalisationmentioning

confidence: 99%

Amide activation: an emerging tool for chemoselective synthesis

et al. 2018

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It is textbook knowledge that carboxamides benefit from increased stabilisation of the electrophilic carbonyl carbon when compared to other carbonyl and carboxyl derivatives. This results in a considerably reduced reactivity towards nucleophiles. Accordingly, a perception has been developed of amides as significantly less useful functional handles than their ester and acid chloride counterparts. However, a significant body of research on the selective activation of amides to achieve powerful transformations under mild conditions has emerged over the past decades. This review article aims at placing electrophilic amide activation in both a historical context and in that of natural product synthesis, highlighting the synthetic applications and the potential of this approach.

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Section: Smi 2 -Mediated Functionalisationmentioning

confidence: 99%

Amide activation: an emerging tool for chemoselective synthesis

et al. 2018

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“…In 2017, Sheng and co-workers reported transamidation of amides catalyzed by heterobimetallic lanthanide alkoxide catalysts (Scheme 53). 82 They found that neodymiumbased catalyst, Nd 2 Na 8 (OCH 2 CF 3 ) 14 (THF) 6 , showed the highest activity. This method works well with 1° amides, DMF, and DMAc, as well as various aliphatic and aromatic amines to give the desired amide products in good to excellent yields.…”

Section: Scheme 48 T-buok-promoted Transition-metal-free Transamidatimentioning

confidence: 99%

Non-Classical Amide Bond Formation: Transamidation and Amidation of Activated Amides and Esters by Selective N–C/O–C Cleavage

Szostak

2020

Synthesis

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In the past several years, tremendous advances have been made in non-classical routes for amide bond formation that involve transamidation and amidation reactions of activated amides and esters. These new methods enable the formation of extremely valuable amide bonds via transition-metal-catalyzed, transition-metal-free, or metal-free pathways by exploiting chemoselective acyl C–X (X = N, O) cleavage under mild conditions. In a broadest sense, these reactions overcome the formidable challenge of activating C–N/C–O bonds of amides or esters by rationally tackling nN → π*C=O delocalization in amides and nO → π*C=O donation in esters. In this account, we summarize the recent remarkable advances in the development of new methods for the synthesis of amides with a focus on (1) transition-metal/NHC-catalyzed C–N/C–O bond activation, (2) transition-metal-free highly selective cleavage of C–N/C–O bonds, (3) the development of new acyl-transfer reagents, and (4) other emerging methods.1 Introduction2 Transamidation of Amides2.1 Transamidation by Metal–NHC Catalysis (Pd–NHC, Ni–NHC)2.2 Transition-Metal-Free Transamidation via Tetrahedral Intermediates2.3 Reductive Transamidation2.4 New Acyl-Transfer Reagents2.5 Tandem Transamidations3 Amidation of Esters3.1 Amidation of Esters by Metal–NHC Catalysis (Pd–NHC, Ni–NHC)3.2 Transition-Metal-Free Amidation of Esters via Tetrahedral Intermediates3.3 Reductive Amidation of Esters4 Transamidations of Amides by Other Mechanisms5 Conclusions and Outlook

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“…Nevertheless, other less important catalysts have to be superficially mentioned, including manganese oxide (MnO 2 ), which was used under solvent-free conditions [ 34 ] with a limited substrate scope but with good yields. The use of lanthanides has also been described; in particular, a bimetallic lanthanum alkoxide [ 35 ], and immobilized Ce(III) [ 36 ] were used as heterogeneous catalysts with the associated advantages, such as easy catalyst recovery and low catalyst charge, but also with the normal issues, such as the catalyst preparation and activation. Some more innovative catalysts have been prepared and used successfully in transamidation.…”

Section: Metal-catalyzed Direct Transamidationsmentioning

confidence: 99%

Direct Transamidation Reactions: Mechanism and Recent Advances

2018

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Amides are undeniably some of the most important compounds in Nature and the chemical industry, being present in biomolecules, materials, pharmaceuticals and many other substances. Unfortunately, the traditional synthesis of amides suffers from some important drawbacks, principally the use of stoichiometric activators or the need to use highly reactive carboxylic acid derivatives. In recent years, the transamidation reaction has emerged as a valuable alternative to prepare amides. The reactivity of amides makes their direct reaction with nitrogen nucleophiles difficult; thus, the direct transamidation reaction needs a catalyst in order to activate the amide moiety and to promote the completion of the reaction because equilibrium is established. In this review, we present research on direct transamidation reactions ranging from studies of the mechanism to the recent developments of more applicable and versatile methodologies, emphasizing those reactions involving activation with metal catalysts.

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An Efficient Heterobimetallic Lanthanide Alkoxide Catalyst for Transamidation of Amides under Solvent‐Free Conditions

Cited by 38 publications

References 125 publications

Amide activation: an emerging tool for chemoselective synthesis

Amide activation: an emerging tool for chemoselective synthesis

Non-Classical Amide Bond Formation: Transamidation and Amidation of Activated Amides and Esters by Selective N–C/O–C Cleavage

Direct Transamidation Reactions: Mechanism and Recent Advances

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