Catalytic hydrogenation of functionalized amides under basic and neutral conditions

John, Jeremy M.; Rasu, Loorthuraja; Antoniuk, Evan R.; Bergens, Steven H.

doi:10.1039/c4cy01227e

Cited by 46 publications

(32 citation statements)

References 33 publications

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“…Reduction of amides without the hydride reagents is a key research area in pharmaceutical industry . Homogeneous catalysts for hydrogenation of amides by H 2 have been reported, but most of them require acidic or basic additives in the reaction mixture as well as an expensive organic ligand. More importantly, most of the homogeneous systems lead to cleavage of C−N bonds of amides to give alcohols and amines .…”

Section: Hydrogenation Of N‐acetylpiperidine (1 A) By Various Catalystsmentioning

confidence: 99%

“…Homogeneous catalysts for hydrogenation of amides by H 2 have been reported, but most of them require acidic or basic additives in the reaction mixture as well as an expensive organic ligand. More importantly, most of the homogeneous systems lead to cleavage of C−N bonds of amides to give alcohols and amines . Klankermayer, Cole‐Hamilton and co‐workers recently developed the first homogenous catalytic system, a Ru‐Triphos complex with an acidic additive, CH 3 SO 3 H or HN(SO 2 CF 3 ) 2 , for the hydrogenation of amides to amines with preservation of the C−N bonds.…”

Section: Hydrogenation Of N‐acetylpiperidine (1 A) By Various Catalystsmentioning

confidence: 99%

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Lewis Acid-Promoted Heterogeneous Platinum Catalysts for Hydrogenation of Amides to Amines

et al. 2016

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For the hydrogenation of a tertiary amide (N-acetylpiperidine), Lewis acidic support materials (Nb 2 O 5 and MoOx/TiO 2 ) increase the catalytic activity of Pt metal nanoparticles by a factor of > 100. In situ infrared (IR) study shows that coordination of the C=O group of amide to surface Lewis acid sites weakens the C= O bond, and the activated amide undergoes hydrogen transfer from H species on Pt sites. Among 19 types of heterogeneous catalysts tested, Pt/Nb 2 O 5 shows the highest catalytic activity. Pt/Nb 2 O 5 is generally effective for the selective hydrogenation of various tertiary amides and e-caprolactam to the corresponding amines under additive-free and solventless conditions and shows an order of higher turnover number (TON) than previously reported catalysts. Pt-MoOx/TiO 2 is the secondary most effective and is reusable 10 times after the reaction.The hydrogenation of carboxylic acids and their derivatives is a key transformation in the pharmaceutical and fine chemical industries and biomass conversion. [1, 2] The reaction is more difficult than the hydrogenation of carbonyl compounds because of the lower electrophilicity of the C=O group in carboxylic acid derivatives. Among the derivatives of carboxylic acid, carboxamides have relatively low electrophilicity of the C=O bond, [2a] and thus catalytic hydrogenation of amides by molecular hydrogen has been a challenging reaction. [1, 2] The synthesis of amines by reduction of the corresponding amides has been carried out by an unsustainable method using excess amount of a dangerous reductant such as LiAlH 4 . [1] Reduction of amides without the hydride reagents is a key research area in pharmaceutical industry. [3] Homogeneous catalysts for hydrogenation of amides by H 2 have been reported, [4][5][6][7][8][9][10][11][12][13] but most of them require acidic or basic additives in the reaction mixture as well as an expensive organic ligand. More importantly, most of the homogeneous systems lead to cleavage of CÀN bonds of amides to give alcohols and amines. [5][6][7][8][9][10][11][12][13] Klankermayer, Cole-Hamilton and co-workers [4] recently developed the first homogenous catalytic system, a Ru-Triphos complex with an acidic additive, CH 3 SO 3 H or HN(SO 2 CF 3 ) 2 , for the hydrogenation of amides to amines with preservation of the CÀN bonds. Early heterogeneous catalysts, such as Cu/Cr oxides, selectivity catalyzed hydrodeoxygenation of amides to amines under harsh conditions (20 À 30 MPa H 2 , ca 250 8C). [1] Ru/Re, Rh/Re and Ru/Mo nanoparticles reported by Fuchikami [14] and Whyman [15] and Rh-MoOx/SiO 2 + CeO 2 [16] are effective catalysts for this reaction under milder conditions, but these catalysts suffer from problems such as need of high H 2 pressure (7-10 MPa) and limited substrate scope. The TiO 2 -supported Pt/Re catalyst [17] was reported to catalyze the hydrogenation of some amides under low H 2 pressure (2 MPa) both in batch and in continuous flow reactors, but the system suffers from limited substrate scope and deactivation in t...

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Section: Hydrogenation Of N‐acetylpiperidine (1 A) By Various Catalystsmentioning

confidence: 99%

Section: Hydrogenation Of N‐acetylpiperidine (1 A) By Various Catalystsmentioning

confidence: 99%

Lewis Acid-Promoted Heterogeneous Platinum Catalysts for Hydrogenation of Amides to Amines

et al. 2016

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“…Given that there are two possible resonance structures for amides and only the ‐C=N‐ resonance structure could conjugate with the phenyl π ring, which favors the challenging reductive cleavage of the inert amide C−N bond, N ‐phenyl‐2‐pyrrolidone was initially selected as a substrate to investigate the catalytic activity of Ru pincer complexes of 1 – 6 in the hydrogenation of lactams. The reaction was carried out in THF under H 2 (50 atm) at 140 °C for 24 h. No reaction occurred when Ru‐MACHO 1 (1 mol %) was applied under base‐free conditions (Table , entry 1).…”

Section: Resultsmentioning

confidence: 99%

Ruthenium‐Pincer‐Catalyzed Hydrogenation of Lactams to Amino Alcohols

Chen

Wang

2018

Chemistry An Asian Journal

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By using the commercially available ruthenium pincer complex (Ru-MACHO-BH) as a catalyst, the challenging direct hydrogenation of lactams and analogues has been successfully accomplished to deliver corresponding value-added amino alcohols in good-to-excellent yields under mild reaction conditions. Remarkably, in addition to N-protected lactams, unprotected ones could also be readily reduced in the presence of a catalytic amount of weak base or even under neutral reaction conditions, which further highlights the broad substrate scope and the protocol efficiency.

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“…In a manner akin to the work of Noyori et al. on metal‐mediated carbonyl group hydrogenation under base‐free conditions, two examples have also emerged that can operate under similar conditions . However, these base‐free catalysts, disclosed by Bergen et al.…”

Section: Methodsmentioning

confidence: 99%

Direct Hydrogenation of a Broad Range of Amides under Base‐free Conditions using an Efficient and Selective Ruthenium(II) Pincer Catalyst

Wang

Liu

et al. 2017

ChemCatChem

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Amines are key intermediates in the chemical industry that can be employed in ad iverse range of applications, which include dyes, drugs, agrochemicals, plastics, surfactants, and textiles through to uses in the paper industry. [1] Traditionally,a mines are prepared by the hydrogenation of amides using stoichiometric or excess amounts of metal hydride reagents (e.g., LiAlH 4 ,N aBH 4 ), [2] boranes, [3] or silanes, [2,4] and this synthetic approach is driven largely by the ready availability of the precursor amides obtained through chemical and biomass processes. [5] Nevertheless, one limitation of this type of hydrogenation is the formationo ft oxic byproducts, which poses problems with disposal. [2,6] As an alternative, the direct hydrogenation of amides into amines using H 2 in the presence of as uitable transition-metal catalysti samore environmentally friendly method. [2] However,t he low electrophilicity of the carbonyl carbon atom and the consequent high thermodynamic andk inetic stabilityr enders this class of carboxylic derivative [2, 7a] difficult to hydrogenate, and as ar esult quite forcing conditions (e.g.,h igh temperaturesa nd pressures) tend to be required. Unsurprisingly, heterogeneous catalysts have led the way and numerouss ystems have been developed, [2, 5a, 8] nonetheless these more robusts ystemsc an suffer from incompatibility problemsa ssociated with functional group intolerance. Consequently,t here has been interesti nt he development of homogeneous variants that can operateu nder milder conditions and offer more control over the hydrogenation process. [6, 7] Indeed, aw ide variety of molecular catalysts have been reported for amide hydrogenation with two types of reactionp athway prevalent, namely,d eoxygenativeh ydrogenation (CÀO cleavage, pathway A) and deaminative hydrogenation (CÀN cleavage, pathway B; Scheme1). [2,9] Ad ecade ago, Cole-Hamilton andc o-workers reported the first homogeneous hydrogenation of amides using Ru(acac) 3 / triphos (acac = acetylacetonate, triphos = 1,1,1-tris(diphenylphosphinomethyl)ethane), [10] throughap redominantly deoxygenative hydrogenation pathway that displayed alow selectivity.T oe nhancet his selectivity,a na cid cocatalyst has been used. [11] Subsequently,s electiveC ÀNb ond hydrogenation of amides hasb een demonstrated using catalysts developed by Milstein et al., [12] Ikariyae tal., [13] Saito et al., [14] Bergens et al., [15] Mashima et al., [16] Beller et al., [17] and others, [18] and the majority of these examples require an excessa mount of base to ensure ag ood activity.I nam anner akin to the work of Noyori et al. on metal-mediated carbonyl group hydrogenation under basefree conditions, [19] two examples have also emerged that can operate under similar conditions. [15c, 17a] However, these basefree catalysts, disclosed by Bergen et al. and Beller et al., [15c,17a] are limited in their substrate scope, and some amides (e.g.,primary) are not conducive to reduction. Hence, there is a The ruthenium(II) complex,[ fac-PN H N]RuH(...

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Catalytic hydrogenation of functionalized amides under basic and neutral conditions

Abstract: A new, base-free high turnover number (TON) catalyst for hydrogenation of simple and functionalized amides is prepared by reacting [Ru(η3-C3H5)(Ph2P(CH2)2NH2)2]BF4 and BH4− under hydrogen.

Cited by 46 publications

References 33 publications

Lewis Acid-Promoted Heterogeneous Platinum Catalysts for Hydrogenation of Amides to Amines

Lewis Acid-Promoted Heterogeneous Platinum Catalysts for Hydrogenation of Amides to Amines

Ruthenium‐Pincer‐Catalyzed Hydrogenation of Lactams to Amino Alcohols

Direct Hydrogenation of a Broad Range of Amides under Base‐free Conditions using an Efficient and Selective Ruthenium(II) Pincer Catalyst

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