Catalytic Hydrogenation of Amides to Amines under Mild Conditions

Stein, Mario; Breit, Bernhard

doi:10.1002/anie.201207803

Cited by 133 publications

(79 citation statements)

References 36 publications

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“…A 1 H− 13 C HMQC experiment revealed a correlation between this signal and a 13 C NMR signal at 55.1 ppm. A DEPT-135 experiment indicated that the signal is from a CH 2 group.…”

Section: Acs Catalysismentioning

confidence: 84%

“…In addition, hydrodeoxygenation of primary and secondary amines often yields mixtures resulting from alkyl group disproportionation. 3,13,17,18 Although a range of late metal complexes have been reported to efficiently reduce amides through hydrosilylation, 8,9,19 new catalytic processes are still needed to address the challenges facing amide deoxygenations (Scheme 1). Few catalytic systems are able to effectively reduce primary, secondary, and tertiary amides, 11 and few catalysts are based on metal complexes other than nonoxophilic late metals.…”

Section: ■ Introductionmentioning

confidence: 99%

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Magnesium-Catalyzed Mild Reduction of Tertiary and Secondary Amides to Amines

et al. 2015

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The first example of a catalytic hydroboration of amides for their deoxygenation to amines is reported. This transformation employs an earth-abundant magnesium-based catalyst. Tertiary and secondary amides are reduced to amines at room temperature in the presence of pinacolborane (HBpin) and catalytic amounts of ToMMgMe (ToM = tris(4,4-dimethyl-2-oxazolinyl)phenylborate). Catalyst initiation and speciation is complex in this system, as revealed by the effects of concentration and order of addition of the substrate and HBpin in the catalytic experiments. ToMMgH2Bpin, formed from ToMMgMe and HBpin, is ruled out as a possible catalytically relevant species by its reaction with N,N-dimethylbenzamide, which gives Me2NBpin and PhBpin through C-N and C-C bond cleavage pathways, respectively. In that reaction, the catalytic product benzyldimethylamine is formed in only low yield. Alternatively, the reaction of ToMMgMe and N,Ndimethylbenzamide slowly gives decomposition of ToMMgMe over 24 h, and this interaction is also ruled out as a catalytically relevant step. Together, these data suggest that catalytic activation of ToMMgMe requires both HBpin and amide, and ToMMgH2Bpin is not a catalytic intermediate. With information on catalyst activation in hand, tertiary amides are selectively reduced to amines in good yield when catalytic amounts of ToMMgMe are added to a mixture of amide and excess HBpin. In addition, secondary amides are reduced in the presence of 10 mol % ToMMgMe and 4 equiv of HBpin. Functional groups such as cyano, nitro, and azo remain intact under the mild reaction conditions. In addition, kinetic experiments and competition experiments indicate that B-H addition to amide C═O is fast, even faster than addition to ester C═O, and requires participation of the catalyst, whereas the turnover-limiting step of the catalyst is deoxygenation. ABSTRACT:The first example of a catalytic hydroboration of amides for their deoxygenation to amines is reported. This transformation employs an earth-abundant magnesium-based catalyst. Tertiary and secondary amides are reduced to amines at room temperature in the presence of pinacolborane (HBpin) and catalytic amounts of To M MgMe (To M = tris(4,4-dimethyl-2-oxazolinyl)phenylborate). Catalyst initiation and speciation is complex in this system, as revealed by the effects of concentration and order of addition of the substrate and HBpin in the catalytic experiments. To M MgH 2 Bpin, formed from To M MgMe and HBpin, is ruled out as a possible catalytically relevant species by its reaction with N,N-dimethylbenzamide, which gives Me 2 NBpin and PhBpin through C−N and C−C bond cleavage pathways, respectively. In that reaction, the catalytic product benzyldimethylamine is formed in only low yield. Alternatively, the reaction of To M MgMe and N,N-dimethylbenzamide slowly gives decomposition of To M

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“…A 1 H− 13 C HMQC experiment revealed a correlation between this signal and a 13 C NMR signal at 55.1 ppm. A DEPT-135 experiment indicated that the signal is from a CH 2 group.…”

Section: Acs Catalysismentioning

confidence: 84%

Section: ■ Introductionmentioning

confidence: 99%

Magnesium-Catalyzed Mild Reduction of Tertiary and Secondary Amides to Amines

et al. 2015

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“…Attention has been attracted to the hydrogenation of crotonaldehyde to crotyl alcohol in aqueous solution for the development of safer and greener process [12]. In addition, water would be generated in many hydrogenation reactions [13]. For example, the hydrogenation of nitrobenzene to aniline produces great amount of water [14].…”

Section: Introductionmentioning

confidence: 99%

Preparation of highly active and hydrothermally stable nickel catalysts

Chen

Shen

2015

Journal of Colloid and Interface Science

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“…Turnovers in 1 h can be as high as 1500 with linearities up to 98.5%. 30 Using our catalytic system under similar conditions to those employed by Drent in toluene, one of Drent's favoured solvents, no conversion was obtained when using a catalyst loading of 0.2 mol% either with aniline or the more nucleophilic 15 in the absence of 2-naphthol ( Table 2, entries 1 and 2), but significant activities (31% conversion for aniline ( (11). e N-phenyl 3-methylhexanamide (12).…”

Section: -Naphthol and Nai As Promotersmentioning

confidence: 88%

Selective formation of α,ω-ester amides from the aminocarbonylation of castor oil derived methyl 10-undecenoate and other unsaturated substrates

Jiménez-Rodríguez

Núñez-Magro

Seidensticker

et al. 2014

Catal. Sci. Technol.

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The reaction of long chain alkenes with CO and aniline in the presence of palladium complexes of 1,2-bis-(ditertbutylphosphinomethyl)benzene produces amides with high linear selectivity, with much higher rates and catalyst stability when 2-naphthol and sodium or potassium iodide are added. Unsaturated esters including methyl 10-undecenoate from castor oil give α,ω-ester amides, whilst reactions in THF give N-phenylpyrrolidine.

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Catalytic Hydrogenation of Amides to Amines under Mild Conditions

Cited by 133 publications

References 36 publications

Magnesium-Catalyzed Mild Reduction of Tertiary and Secondary Amides to Amines

Magnesium-Catalyzed Mild Reduction of Tertiary and Secondary Amides to Amines

Preparation of highly active and hydrothermally stable nickel catalysts

Selective formation of α,ω-ester amides from the aminocarbonylation of castor oil derived methyl 10-undecenoate and other unsaturated substrates

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