Cobalt‐Catalyzed Reductive Alkylation of Amines with Carboxylic Acids

Emayavaramban, Balakumar; Chakraborty, Priyanka; Sundararaju, Basker

doi:10.1002/cssc.201802144

Cited by 20 publications

(14 citation statements)

References 83 publications

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“…The same air-stable Co/Triphos catalyst system as described above was used (Scheme 139). 260 A selective monoalkylation was achieved in good to high yields (45−94%) with various carboxylic acids.…”

Section: Group 8 (Fe Ru) Metal-catalyzed Reductive Aminationmentioning

confidence: 99%

Transition-Metal-Catalyzed Reductive Amination Employing Hydrogen

2020

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The reductive amination, the reaction of an aldehyde or a ketone with ammonia or an amine in the presence of a reducing agent and often a catalyst, is an important amine synthesis and has been intensively investigated in academia and industry for a century. Besides aldehydes, ketones, or amines, starting materials have been used that can be converted into an aldehyde or ketone (for instance, carboxylic acids or organic carbonate or nitriles) or into an amine (for instance, a nitro compound) in the presence of the same reducing agent and catalyst. Mechanistically, the reaction starts with a condensation step during which the carbonyl compound reacts with ammonia or an amine, forming the corresponding imine followed by the reduction of the imine to the alkyl amine product. Many of these reduction steps require the presence of a catalyst to activate the reducing agent. The reductive amination is impressive with regard to the product scope since primary, secondary, and tertiary alkyl amines are accessible and hydrogen is the most attractive reducing agent, especially if large-scale product formation is an issue, since hydrogen is inexpensive and abundantly available. Alkyl amines are intensively produced and use fine and bulk chemicals. They are key functional groups in many pharmaceuticals, agro chemicals, or materials. In this review, we summarize the work published on reductive amination employing hydrogen as the reducing agent. No comprehensive review focusing on this subject has been published since 1948, albeit many interesting summaries dealing with one or the other aspect of reductive amination have appeared. Impressive progress in using catalysts based on earth-abundant metals, especially nanostructured heterogeneous catalysts, has been made during the early development of the field and in recent years.

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Section: Group 8 (Fe Ru) Metal-catalyzed Reductive Aminationmentioning

confidence: 99%

Transition-Metal-Catalyzed Reductive Amination Employing Hydrogen

2020

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“…They performed the hydrogenation of nonanoic acid in the presence of NH 3 to give a mixture of Noctylamines 55,56 . After this example, interesting developments in this area have been made by the groups of Cantat 138 , Beller (2015, 2016, and 2018) [139][140][141][142] , Cole-Hamilton (2017) 143,144 , and Sundararaju 145 . In all these cases, the active catalyst employed Triphos (Fig.…”

Section: Related Catalytic Hydrogenative Transformationsmentioning

confidence: 99%

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

et al. 2020

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Catalytic hydrogenation of amides is of great interest for chemists working in organic synthesis, as the resulting amines are widely featured in natural products, drugs, agrochemicals, dyes, etc. Compared to traditional reduction of amides using (over)stoichiometric reductants, the direct hydrogenation of amides using molecular hydrogen represents a greener approach. Furthermore, amide hydrogenation is a highly versatile transformation, since not only higher amines (obtained by CO cleavage), but also lower amines and alcohols, or amino alcohols (obtained by C-N cleavage) can be selectively accessed by fine tuning of reaction conditions. This review describes the most recent advances in the area of amide hydrogenation using H 2 exclusively and molecularly defined homogeneous as well as nanostructured heterogeneous catalysts, with a special focus on catalyst development and synthetic applications. T he development of green and sustainable methods is a central focus of modern organic synthesis and its applications in various areas of the chemical industry. In this respect, many reduction reactions, traditionally employing stoichiometric amounts of metal hydrides with inherent low atom efficiency 1 , can be favorably replaced by catalytic hydrogenations. In fact, the combination of molecular hydrogen and catalysts does not only allow avoiding formation of waste products 2 , it also opens the door to clean transformations based on renewable energies as the conversion of solar or wind energy to "green" hydrogen is likely to be implemented in the coming years. Among the many reduction reactions known, amide hydrogenation can be encountered as one of the most desired considering the importance of the derived amines in several branches of chemical industry. In fact, since the start of the Green Chemistry Institute Pharmaceutical Roundtable in the United States in 2005, several projects aimed to the achievement of a practical amide hydrogenation methodology have been supported 3,4. The long-term interest of the pharmaceutical industry in this specific transformation is explained by the fact that it ideally affords structurally complex amines, present in many of the currently employed drugs. Furthermore, amines are also in bulk and fine chemicals used in the manufacture of plastics, textiles, surfactants, dyes, and many more 5. Amides play a central role in the chemistry of life, as they are the key elements to generate peptides and proteins from amino acid monomers. At the same time, they are present in artificial

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“…Encouraged by these early successes, a variety of catalytic systems for reductive amination were reported from 2015 to 2020 (Scheme 17 A,B). The diversity of homogeneous metal catalysts significantly evolved, ranging from noble metals like Rh, [103] Ru [104, 105] and Ir [106] to base metals like Fe, [107, 108] Co, [109, 110] Ni, [111] Cu, [112] Zn [113] and Mo, [114] and more excitingly, some main group elements such as In [115] and B [116, 117] were found to be effective (Scheme 17 A, gray frames). Parallel to the great advancement of homogeneous catalysis, several solid‐supported heterogeneous catalysts featuring the advantages of robustness and recyclability were also documented (Scheme 17 A, black frames) [118–121] .…”

Section: Deoxygenative Functionalizations Of Carboxylic Acidsmentioning

confidence: 99%

Deoxygenative Functionalizations of Aldehydes, Ketones and Carboxylic Acids

Huang

2022

Angew Chem Int Ed

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The simple and efficient conversion of carbonyl compounds into functionalized alkanes via deoxygenation is highly enabling in chemical synthesis. This Review covers the recent methodology development in carbonyl and carboxyl deoxygenative functionalizations, highlighting some representative and significant contributions in this field. These advances are categorized based on the reactivity patterns of some oxygenated feedstock compounds, including aldehydes, ketones and carboxylic acids. Four types of reactive intermediates arising from aldehydes and ketones during the deoxygenation, namely, bis‐electrophiles, carbenoids, bis‐nucleophiles and alkyl radical equivalents, are presented, while the carboxylic acids mainly behave as tris‐electrophiles when deoxygenated. In each subcategory, selected examples are organized according to the type of bond formation and discussed from a generalized mechanistic perspective.

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Cobalt‐Catalyzed Reductive Alkylation of Amines with Carboxylic Acids

Cited by 20 publications

References 83 publications

Transition-Metal-Catalyzed Reductive Amination Employing Hydrogen

Transition-Metal-Catalyzed Reductive Amination Employing Hydrogen

Homogeneous and heterogeneous catalytic reduction of amides and related compounds using molecular hydrogen

Deoxygenative Functionalizations of Aldehydes, Ketones and Carboxylic Acids

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