Highly Selective, Efficient Deoxygenative Hydrogenation of Amides Catalyzed by a Manganese Pincer Complex via Metal–Ligand Cooperation

Zou, You‐Quan; Chakraborty, Subrata; Nerush, Alexander; Oren, Dror; Diskin‐Posner, Yael; Ben‐David, Yehoshoa; Milstein, David

doi:10.1021/acscatal.8b02902

Cited by 108 publications

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References 64 publications

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“…In order to get insights into the reaction mechanism, we first examined the reduction of imine 15 in the absence of BF 3 ⋅ OEt 2 , and the target product was obtained in 97% yield (Scheme a), indicating the involvement of an imine intermediate in the reaction. On the basis of Zhou's report, it appears that the role of BF 3 ⋅ OEt 2 co‐catalyst in this reaction is to activate the amide carbonyl group via the in situ formation of amide‐boron adduct. This was confirmed by the fact that treatment of the separately prepared adduct 1 r‐ BF 3 with AB under B(C 6 F 5 ) 3 catalysis resulted in the generation of the desired product in 95% yield (Scheme b).…”

Section: Resultsmentioning

confidence: 99%

B(C₆F₅)₃‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

et al. 2019

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The first B(C 6 F 5 ) 3 -catalyzed deoxygenative reduction of amides into the corresponding amines with readily accessible and stable ammonia borane (AB) as a reducing agent under mild reaction conditions is reported. This metal-free protocol provides facile access to a wide range of structurally diverse amine products in good to excellent yields, and various functional groups including those that are reduction-sensitive were well tolerated. This new method is also applicable to chiral amide substrates without erosion of the enantiomeric purity. The role of BF 3 · OEt 2 co-catalyst in this reaction is to activate the amide carbonyl group via the in situ formation of an amide-boron adduct.

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Section: Resultsmentioning

confidence: 99%

B(C₆F₅)₃‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

et al. 2019

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“…In 2018, an interesting advancement was reported by Milstein group, who achieved the first C-O hydrogenation of amides with a molecularly defined base metal catalyst (Fig. 3i) 64 . Explicitly, a [ 65 .…”

Section: Development Of Homogeneous Catalystsmentioning

confidence: 97%

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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“…Since aromatic rings often structurally compose many of the amines used in life science applications, these processes represent important contributions in the synthetic chemist's toolbox, on both an academic and an industrial scale. Alternatively, some elegant homogeneous approaches using Ru, 32 Ir 33 and Mn 34 pincer complexes in combination with specific Brönsted or Lewis acid co-catalysts have also been disclosed for the hydrogenation of amides to the corresponding alkylated amines, which fully retained the aromaticity. In contrast, the use of homogeneous catalysts is usually associated with the preparation of the respective alcohols and amines after C-N bond hydrogenolysis.…”

Section: Introductionmentioning

confidence: 99%

Palladium doping of In₂O₃ towards a general and selective catalytic hydrogenation of amides to amines and alcohols

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Martı́n

et al. 2019

Catal. Sci. Technol.

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Highly Selective, Efficient Deoxygenative Hydrogenation of Amides Catalyzed by a Manganese Pincer Complex via Metal–Ligand Cooperation

Cited by 108 publications

References 64 publications

B(C₆F₅)₃‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

B(C₆F₅)₃‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

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

Palladium doping of In₂O₃ towards a general and selective catalytic hydrogenation of amides to amines and alcohols

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Highly Selective, Efficient Deoxygenative Hydrogenation of Amides Catalyzed by a Manganese Pincer Complex via Metal–Ligand Cooperation

Cited by 108 publications

References 64 publications

B(C6F5)3‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

B(C6F5)3‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

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

Palladium doping of In2O3 towards a general and selective catalytic hydrogenation of amides to amines and alcohols

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B(C₆F₅)₃‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

B(C₆F₅)₃‐Catalyzed Deoxygenative Reduction of Amides to Amines with Ammonia Borane

Palladium doping of In₂O₃ towards a general and selective catalytic hydrogenation of amides to amines and alcohols