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PROCESS FOR PRODUCING A CATALYST, CATALYST AND USE THEREOF
A process for producing a supported catalyst comprising metal nanoparticles, said process comprises the following steps: (a) preparing a supported catalyst comprising metal nanoparticles; (b) peducing the catalyst of step (a); (c) treating the reduced catalyst of step (b) with at least one alcohol, and (d) calcining the treated catalyst of step (c) to remove carbon species, to produce said supported catalyst. A catalyst obtainable from this process can be used in amination, hydrogenation, dehydrogenation, hydrogenolysis and aerobic oxidation reactions.
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(2021/06/26)

Air Stable Iridium Catalysts for Direct Reductive Amination of Ketones
Half-sandwich iridium complexes bearing bidentate urea-phosphorus ligands were found to catalyze the direct reductive amination of aromatic and aliphatic ketones under mild conditions at 0.5 mol % loading with high selectivity towards primary amines. One of the complexes was found to be active in both the Leuckart–Wallach (NH4CO2H) type reaction as well as in the hydrogenative (H2/NH4AcO) reductive amination. The protocol with ammonium formate does not require an inert atmosphere, dry solvents, as well as additives and in contrast to previous reports takes place in hexafluoroisopropanol (HFIP) instead of methanol. Applying NH4CO2D or D2 resulted in a high degree of deuterium incorporation into the primary amine α-position.
Polishchuk, Iuliia,Sklyaruk, Jan,Lebedev, Yury,Rueping, Magnus
supporting information
p. 5919 - 5922
(2021/03/08)

Direct reductive amination of ketones with ammonium salt catalysed by Cp*Ir(iii) complexes bearing an amidato ligand
A series of half-sandwich Ir(iii) complexes1-6bearing an amidato bidentate ligand were conveniently synthesized and applied to the catalytic Leuckart-Wallach reaction to produce racemic α-chiral primary amines. With 0.1 mol% of complex1, a broad range of ketones, including aryl ketones, dialkyl ketones, cyclic ketones, α-keto acids, α-keto esters and diketones, could be transformed to their corresponding primary amines with moderate to excellent yields (40%-95%). Asymmetric transformation was also attempted with chiral Ir complexes3-6, and 16% ee of the desired primary amine was obtained. Despite the unsatisfactory enantio-control achieved so far, the current exploration might stimulate more efforts towards the discovery of better chiral catalysts for this challenging but important transformation.
Dai, Zengjin,Pan, Ying-Min,Wang, Shou-Guo,Yin, Qin,Zhang, Xumu
supporting information
p. 8934 - 8939
(2021/11/04)

Ruthenium-Catalyzed Hydroamination of Unactivated Terminal Alkenes with Stoichiometric Amounts of Alkene and an Ammonia Surrogate by Sequential Oxidation and Reduction
Hydroamination of alkenes catalyzed by transition-metal complexes is an atom-economical method for the synthesis of amines, but reactions of unactivated alkenes remain inefficient. Additions of N-H bonds to such alkenes catalyzed by iridium, gold, and lanthanide catalysts are known, but they have required a large excess of the alkene. New mechanisms for such processes involving metals rarely used previously for hydroamination could enable these reactions to occur with greater efficiency. We report ruthenium-catalyzed intermolecular hydroaminations of a variety of unactivated terminal alkenes without the need for an excess of alkene and with 2-aminopyridine as an ammonia surrogate to give the Markovnikov addition product. Ruthenium complexes have rarely been used for hydroaminations and have not previously catalyzed such reactions with unactivated alkenes. Identification of the catalyst resting state, kinetic measurements, deuterium labeling studies, and DFT computations were conducted and, together, strongly suggest that this process occurs by a new mechanism for hydroamination occurring by oxidative amination in concert with reduction of the resulting imine.
Ma, Senjie,Hill, Christopher K.,Olen, Casey L.,Hartwig, John F.
supporting information
p. 359 - 368
(2021/01/13)

Asymmetric synthesis of primary amines catalyzed by thermotolerant fungal reductive aminases
Chiral primary amines are important intermediates in the synthesis of pharmaceutical compounds. Fungal reductive aminases (RedAms) are NADPH-dependent dehydrogenases that catalyse reductive amination of a range of ketones with short-chain primary amines supplied in an equimolar ratio to give corresponding secondary amines. Herein we describe structural and biochemical characterisation as well as synthetic applications of two RedAms fromNeosartoryaspp. (NfRedAm andNfisRedAm) that display a distinctive activity amongst fungal RedAms, namely a superior ability to use ammonia as the amine partner. Using these enzymes, we demonstrate the synthesis of a broad range of primary amines, with conversions up to >97% and excellent enantiomeric excess. Temperature dependent studies showed that these homologues also possess greater thermal stability compared to other enzymes within this family. Their synthetic applicability is further demonstrated by the production of several primary and secondary amines with turnover numbers (TN) up to 14 000 as well as continous flow reactions, obtaining chiral amines such as (R)-2-aminohexane in space time yields up to 8.1 g L?1h?1. The remarkable features ofNfRedAmand NfisRedAm highlight their potential for wider synthetic application as well as expanding the biocatalytic toolbox available for chiral amine synthesis.
Cosgrove, Sebastian C.,Grogan, Gideon,Mangas-Sanchez, Juan,Marshall, James R.,Palmer, Ryan B.,Ramsden, Jeremy I.,Sharma, Mahima,Thorpe, Thomas W.,Turner, Nicholas J.
p. 5052 - 5057
(2020/06/09)

Ruthenium Catalyzed Direct Asymmetric Reductive Amination of Simple Aliphatic Ketones Using Ammonium Iodide and Hydrogen
The direct conversion of ketones into chiral primary amines is a key transformation in chemistry. Here, we present a ruthenium catalyzed asymmetric reductive amination (ARA) of purely aliphatic ketones with good yields and moderate enantioselectivity: up to 99 percent yield and 74 percent ee. The strategy involves [Ru(PPh3)3H(CO)Cl] in combination with the ligand (S,S)-f-binaphane as the catalyst, NH4I as the amine source and H2 as the reductant. This is a straightforward and user-friendly process to access industrially relevant chiral aliphatic primary amines. Although the enantioselectivity with this approach is only moderate, to the extent of our knowledge, the maximum ee of 74 percent achieved with this system is the highest reported till now apart from enzyme catalysis for the direct transformation of ketones into chiral aliphatic primary amines.
Ernst, Martin,Ghosh, Tamal,Hashmi, A. Stephen K.,Schaub, Thomas
supporting information

(2020/07/14)

Separate Sets of Mutations Enhance Activity and Substrate Scope of Amine Dehydrogenase
Mutations were introduced into the leucine amine dehydrogenase (L-AmDH) derived from G. stearothermophilus leucine dehydrogenase (LeuDH) with the goals of increased activity and expanded substrate acceptance. A triple variant (L-AmDH-TV) including D32A, F101S, and C290V showed an average of 2.5-fold higher activity toward aliphatic ketones and an 8.0 °C increase in melting temperature. L-AmDH-TV did not show significant changes in relative activity for different substrates. In contrast, L39A, L39G, A112G, and T133G in varied combinations added to L-AmDH-TV changed the shape of the substrate binding pocket. L-AmDH-TV was not active on ketones larger than 2-hexanone. L39A and L39G enabled activity for straight-chain ketones as large as 2-decanone and in combination with A112G enabled activity toward longer branched ketones including 5-methyl-2-octanone.
Franklin, Robert D.,Mount, Conner J.,Bommarius, Bettina R.,Bommarius, Andreas S.
p. 2436 - 2439
(2020/04/16)

Development of an engineered thermostable amine dehydrogenase for the synthesis of structurally diverse chiral amines
Amine dehydrogenases (AmDHs) are emerging as a class of attractive biocatalysts for synthesizing chiral amines via asymmetric reductive amination of ketones with inexpensive ammonia as an amino donor. However, the AmDHs developed to date exhibit limited substrate scope. Here, using directed evolution, we engineered a GkAmDH based on a thermostable phenylalanine dehydrogenase from Geobacillus kaustophilus. The newly developed AmDH is able to catalyze reductive amination of a diverse set of ketones and functionalized hydroxy ketones with ammonia or primary amines with up to >99% conversion, thus accessing structurally diverse chiral primary and secondary amines and chiral vicinal amino alcohols, with excellent enantioselectivity (up to >99% ee) and releasing water as the sole by-product.
Chen, Fei-Fei,Chen, Qi,Liu, Lei,Wang, Dong-Hao,Wang, Zhi-Long,Xu, Jian-He,Zhang, Zhi-Jun,Zheng, Gao-Wei
p. 2353 - 2358
(2020/05/13)

One-pot reductive amination of carboxylic acids: a sustainable method for primary amine synthesis
The reductive amination of carboxylic acids is a very green, efficient and sustainable method for the production of (bio-based) amines. However, with current technology, this reaction requires two to three reaction steps. Here, we report the first (heterogeneous) catalytic system for the one-pot reductive amination of carboxylic acids to amines, with solely H2 and NH3 as the reactants. This reaction can be performed with relatively cheap ruthenium-tungsten bimetallic catalysts in the green and benign solvent cyclopentyl methyl ether (CPME). Selectivities of up to 99% for the primary amine could be achieved at high conversions. Additionally, the catalyst is recyclable and tolerant for common impurities such as water and cations (e.g. sodium carboxylate).
Coeck, Robin,De Vos, Dirk E.
supporting information
p. 5105 - 5114
(2020/08/25)

Ambient-Temperature Synthesis of Primary Amines via Reductive Amination of Carbonyl Compounds
Efficient synthesis of primary amines via low-temperature reductive amination of carbonyl compounds using NH3 and H2 as the nitrogen and hydrogen resources is highly desired and challenging in the chemistry community. Herein, we employed naturally occurring phytic acid as a renewable precursor to fabricate titanium phosphate (TiP)-supported Ru nanocatalysts with different reduction degrees of RuO2 (Ru/TiP-x, x represents the reduction temperature) by combining ball milling and molten-salt processes. Very interestingly, the obtained Ru/TiP-100 had good catalytic performance for the reductive amination of carbonyl compounds at ambient temperature, resulting from the synergistic cooperation of the support (TiP) and the Ru/RuO2 with a suitable proportion of Ru0 (52%). Various carbonyl compounds could be efficiently converted into the corresponding primary amines with high yields. More importantly, the conversion of other substrates with reducible groups could also be achieved at ambient temperature. Detailed investigations indicated that the partially reduced Ru and the support (TiP) were indispensable. The high activity and selectivity of Ru/TiP-100 catalyst originates from the relatively high acidity and the suitable electron density of metallic Ru0.
Xie, Chao,Song, Jinliang,Hua, Manli,Hu, Yue,Huang, Xin,Wu, Haoran,Yang, Guanying,Han, Buxing
p. 7763 - 7772
(2020/08/21)

Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions
The primary objective of many researchers in chemical synthesis is the development of recyclable and easily accessible catalysts. These catalysts should preferably be made from Earth-abundant metals and have the ability to be utilised in the synthesis of pharmaceutically important compounds. Amines are classified as privileged compounds, and are used extensively in the fine and bulk chemical industries, as well as in pharmaceutical and materials research. In many laboratories and in industry, transition metal catalysed reductive amination of carbonyl compounds is performed using predominantly ammonia and H2. However, these reactions usually require precious metal-based catalysts or RANEY nickel, and require harsh reaction conditions and yield low selectivity for the desired products. Herein, we describe a simple and environmentally friendly method for the preparation of thin graphene spheres that encapsulate uniform Ni/NiO nanoalloy catalysts (Ni/NiO?C) using nickel citrate as the precursor. The resulting catalysts are stable and reusable and were successfully used for the synthesis of primary, secondary, tertiary, and N-methylamines (more than 62 examples). The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, and H2 under very mild industrially viable and scalable conditions (80 °C and 1 MPa H2 pressure, 4 h), offering cost-effective access to numerous functionalized, structurally diverse linear and branched benzylic, heterocyclic, and aliphatic amines including drugs and steroid derivatives. We have also demonstrated the scale-up of the heterogeneous amination protocol to gram-scale synthesis. Furthermore, the catalyst can be immobilized on a magnetic stirring bar and be conveniently recycled up to five times without any significant loss of catalytic activity and selectivity for the product.
Cui, Zhibing,Liu, Jianguo,Liu, Qiying,Ma, Longlong,Singh, Thishana,Wang, Chenguang,Wang, Nan,Zhu, Yuting
supporting information
p. 7387 - 7397
(2020/11/19)

Novel heterogeneous ruthenium racemization catalyst for dynamic kinetic resolution of chiral aliphatic amines
Only few dynamic kinetic resolution (DKR) systems are known for chiral aliphatic amines due to the difficult racemization of these amines. In this work, each aspect of the DKR of aliphatic amines is investigated. Various ruthenium catalysts were evaluated to increase their applicability in racemization as an alternative to established heterogeneous palladium catalysts. A heterogeneous Ru(iii) on zeolite catalyst showed good activity for racemization in aprotic polar media. Next, kinetic resolution was evaluated; excellent yields (50%) and selectivities (>99%) were obtained in apolar solvents when employing isopentyl propionate as resolving agent. After evaluation of both components, the complete dynamic kinetic resolution of an aliphatic amine was established with good selectivity (97%), enantiomeric excess (96%) and a yield exceeding the kinetic resolution limit of 50%.
Adriaensen, Koen,Vercammen, Jannick,Van Goethem, Cédric,Eyley, Samuel,Vankelecom, Ivo,Thielemans, Wim,De Vos, Dirk
p. 85 - 93
(2020/01/13)

Upgraded Bioelectrocatalytic N2 Fixation: From N2 to Chiral Amine Intermediates
Enantiomerically pure chiral amines are of increasing value in the preparation of bioactive compounds, pharmaceuticals, and agrochemicals. ω-Transaminase (ω-TA) is an ideal catalyst for asymmetric amination because of its excellent enantioselectivity and wide substrate scope. To shift the equilibrium of reactions catalyzed by ω-TA to the side of the amine product, an upgraded N2 fixation system based on bioelectrocatalysis was developed to realize the conversion from N2 to chiral amine intermediates. The produced NH3 was in situ reacted with l-alanine dehydrogenase to generate alanine with NADH as a coenzyme. ω-TA transferred the amino group from alanine to ketone substrates and finally produced the desired chiral amine intermediates. The cathode of the upgraded N2 fixation system supplied enough reducing power to synchronously realize the regeneration of reduced methyl viologen (MV?+) and NADH for the nitrogenase and l-alanine dehydrogenase. The coproduct, pyruvate, was consumed by l-alanine dehydrogenase to regenerate alanine and push the equilibrium to the side of amine. After 10 h of reaction, the concentration of 1-methyl-3-phenylpropylamine achieved 0.54 mM with the 27.6% highest faradaic efficiency and >99% enantiomeric excess (eep). Because of the wide substrate scope and excellent enantioselectivity of ω-TA, the upgraded N2 fixation system has great potential to produce a variety of chiral amine intermediates for pharmaceuticals and other applications.
Chen, Hui,Cai, Rong,Patel, Janki,Dong, Fangyuan,Chen, Hsiaonung,Minteer, Shelley D.
p. 4963 - 4971
(2019/03/26)

Morphology-Tuned Activity of Ru/Nb2O5 Catalysts for Ketone Reductive Amination
Amines are important compounds in natural products and medicines. Specifically, cyclopentylamine is one of the value-added chemicals widely used in the production of pesticides, cosmetics and medicines. In this work, three Ru/Nb2O5 catalysts with different Nb2O5 morphologies were used in the reductive amination of cyclopentanone under mild reaction conditions (90 °C, 2 MPa H2), among which 1 %Ru/Nb2O5?L catalyst exhibits best performance with the yield of cyclopentylamine reaching 84 %. This catalytic system is stable and has not significant deactivation even after 5 runs in the durability test. In addition, this catalyst can be extended to a series of aldehydes/ketones. Further comprehensive characterizations (XPS analysis and CO-adsorption DRIFT) reveal that the electronic effect of Ru species can be ruled out; instead, the activity of the catalyst is strongly influenced by the geometric effect. Layered Nb2O5 material possesses the highest surface area, resulting in the highest Ru dispersion, and therefore shows the highest catalytic activity. The in-situ DRIFT-MS technique was also used to reveal and understand the reaction mechanism. It is found that Ru species play a key role in activating carbonyl groups. This study illustrates a promising application of Ru/Nb2O5-Layer catalyst in the synthesis of amine and provides an understanding to the reaction mechanism.
Guo, Wanjun,Tong, Tao,Liu, Xiaohui,Guo, Yong,Wang, Yanqin
p. 4130 - 4138
(2019/05/24)

Efficient synthesis of enantiopure amines from alcohols using resting: E. coli cells and ammonia
α-Chiral amines are pivotal building blocks for chemical manufacturing. Stereoselective amination of alcohols is receiving increased interest due to its higher atom-efficiency and overall improved environmental footprint compared with other chemocatalytic and biocatalytic methods. We previously developed a hydrogen-borrowing amination by combining an alcohol dehydrogenase (ADH) with an amine dehydrogenase (AmDH) in vitro. Herein, we implemented the ADH-AmDH bioamination in resting Escherichia coli cells for the first time. Different genetic constructs were created and tested in order to obtain balanced expression levels of the dehydrogenase enzymes in E. coli. Using the optimized constructs, the influence of several parameters towards the productivity of the system were investigated such as the intracellular NAD+/NADH redox balance, the cell loading, the survival rate of recombinant E. coli cells, the possible toxicity of the components of the reaction at different concentrations and the influence of different substrates and cosolvents. In particular, the cofactor redox-balance for the bioamination was maintained by the addition of moderate and precise amounts of glucose. Higher concentrations of certain amine products resulted in toxicity and cell death, which could be alleviated by the addition of a co-solvent. Notably, amine formation was consistent using several independently grown E. coli batches. The optimized E. coli/ADH-AmDH strains produced enantiopure amines from the alcohols with up to 80% conversion and a molar productivity up to 15 mM. Practical applicability was demonstrated in a gram-scale biotransformation. In summary, the present E. coli-ADH-AmDH system represents an important advancement towards the development of 'green', efficient and selective biocatalytic processes for the amination of alcohols.
Houwman, Joseline A.,Knaus, Tanja,Costa, Magda,Mutti, Francesco G.
supporting information
p. 3846 - 3857
(2019/07/31)

Rapid and Quantitative Profiling of Substrate Specificity of ω-Transaminases for Ketones
ω-Transaminases (ω-TAs) have gained growing attention owing to their capability for asymmetric synthesis of chiral amines from ketones. Reliable high-throughput activity assay of ω-TAs is essential in carrying out extensive substrate profiling and establishing a robust screening platform. Here we report spectrophotometric and colorimetric methods enabling rapid quantitation of ω-TA activities toward ketones in a 96-well microplate format. The assay methods employ benzylamine, a reactive amino donor for ω-TAs, as a cosubstrate and exploit aldehyde dehydrogenase (ALDH) as a reporter enzyme, leading to formation of benzaldehyde detectable by ALDH owing to concomitant NADH generation. Spectrophotometric substrate profiling of two wild-type ω-TAs of opposite stereoselectivity was carried out at 340 nm with 22 ketones, revealing subtle differences in substrate specificities that were consistent with docking simulation results obtained with cognate amines. Colorimetric readout for naked eye detection of the ω-TA activity was also demonstrated by supplementing the assay mixture with color-developing reagents whose color reaction could be quantified at 580 nm. The colorimetric assay was applied to substrate profiling of an engineered ω-TA for 24 ketones, leading to rapid identification of reactive ketones. The ALDH-based assay is expected to be promising for high-throughput screening of enzyme collections and mutant libraries to fish out the best ω-TA candidate as well as to tailor enzyme properties for efficient amination of a target ketone.
Han, Sang-Woo,Shin, Jong-Shik
p. 3287 - 3295
(2019/06/21)

Reshaping the Active Pocket of Amine Dehydrogenases for Asymmetric Synthesis of Bulky Aliphatic Amines
The asymmetric reductive amination of ketones with ammonia using engineered amine dehydrogenases (AmDHs) is a particularly attractive and environmentally friendly method for the synthesis of chiral amines. However, one major challenge for these engineered AmDHs is their limited range of accepted substrates. Herein, several engineered AmDHs were developed through the evolution of naturally occurring leucine dehydrogenases, which displayed good amination activity toward aliphatic ketones but restricted catalytic scope for short-chain substrates. Computational analysis helped identify two residues, located at the distal end of the substrate-binding cavity, that generate steric hindrance and prevent the binding of bulky aliphatic ketones. By fine-tuning these two key hotspots, the resulting AmDH mutants are able to accept previously inaccessible bulky substrates. More importantly, the mutations were also proved applicable for expanding the substrate scope of other homologous AmDHs with sequence identities as low as 70%, indicating a broad effect on the development of AmDHs and the synthesis of structurally diverse chiral amines.
Chen, Fei-Fei,Zheng, Gao-Wei,Liu, Lei,Li, Hao,Chen, Qi,Li, Fu-Long,Li, Chun-Xiu,Xu, Jian-He
p. 2622 - 2628
(2018/03/13)

3,3-Dimethoxypropylsulfonyl Group: A new versatile protecting and activating group for amine synthesis
3,3-Dimethoxypropylsulfonyl (Dimps) chloride was prepared and used as a new versatile sulfonating agent for ammonia, primary and secondary amines to afford corresponding Dimps-amides in excellent yields. The resulting N-nonsubstituted and N-monosubstituted Dimps-amides, activated amines, were alkylated satisfactorily under new Mitsunobu conditions. The Dimps group was removed by treatment in aqueous solution under acidic followed by basic conditions. Furthermore, epilachnene, the defensive droplets from the Mexican bean beetle, Epilachna varivestis, was synthesized utilizing this Dimps methodology in short steps.
Sakamoto, Izumi,Iwaoka, Kazuya,Kawada, Yuta,Naito, Takanori,Makida, Kazuyoshi,Takeuchi, Yuki,Nishii, Takeshi,Horikawa, Mitsuyo,Kaku, Hiroto,Tsunoda, Tetsuto
p. 3052 - 3060
(2018/05/23)

Vicinal Diamines as Smart Cosubstrates in the Transaminase-Catalyzed Asymmetric Amination of Ketones
Transaminases (TAs) have recently been established as catalysts for the asymmetric, reductive amination of prochiral ketones. Depending on the ketone substrate and the amine donor (the cosubstrate), equilibrium constants may limit high conversions; thus, methods to overcome this limitation are required. Removal of the co-product from the reaction equilibrium through spontaneous, intramolecular reactions has provided a successful solution to this problem; therefore, these amine donors have been named “smart cosubstrates”. Here, we present a comparison of various bifunctional amine donors including vicinal diamines as potential structural cosubstrate motifs. Upon TA-catalyzed deamination of 1,2-diamines, spontaneous dimerization of the resulting α-aminoketones and oxidation gave heteroaromatic pyrazines.
Payer, Stefan E.,Schrittwieser, Joerg H.,Kroutil, Wolfgang
supporting information
p. 2553 - 2559
(2017/05/12)

Amine dehydrogenases: Efficient biocatalysts for the reductive amination of carbonyl compounds
Amines constitute the major targets for the production of a plethora of chemical compounds that have applications in the pharmaceutical, agrochemical and bulk chemical industries. However, the asymmetric synthesis of α-chiral amines with elevated catalytic efficiency and atom economy is still a very challenging synthetic problem. Here, we investigated the biocatalytic reductive amination of carbonyl compounds employing a rising class of enzymes for amine synthesis: amine dehydrogenases (AmDHs). The three AmDHs from this study-operating in tandem with a formate dehydrogenase from Candida boidinii (Cb-FDH) for the recycling of the nicotinamide coenzyme-performed the efficient amination of a range of diverse aromatic and aliphatic ketones and aldehydes with up to quantitative conversion and elevated turnover numbers (TONs). Moreover, the reductive amination of prochiral ketones proceeded with perfect stereoselectivity, always affording the (R)-configured amines with more than 99% enantiomeric excess. The most suitable amine dehydrogenase, the optimised catalyst loading and the required reaction time were determined for each substrate. The biocatalytic reductive amination with this dual-enzyme system (AmDH-Cb-FDH) possesses elevated atom efficiency as it utilizes the ammonium formate buffer as the source of both nitrogen and reducing equivalents. Inorganic carbonate is the sole by-product.
Knaus, Tanja,B?hmer, Wesley,Mutti, Francesco G.
p. 453 - 463
(2017/08/14)

In vitro biocatalytic pathway design: Orthogonal network for the quantitative and stereospecific amination of alcohols
The direct and efficient conversion of alcohols into amines is a pivotal transformation in chemistry. Here, we present an artificial, oxidation-reduction, biocatalytic network that employs five enzymes (alcohol dehydrogenase, NADP-oxidase, catalase, amine dehydrogenase and formate dehydrogenase) in two concurrent and orthogonal cycles. The NADP-dependent oxidative cycle converts a diverse range of aromatic and aliphatic alcohol substrates to the carbonyl compound intermediates, whereas the NAD-dependent reductive aminating cycle generates the related amine products with >99% enantiomeric excess (R) and up to >99% conversion. The elevated conversions stem from the favorable thermodynamic equilibrium (K′eq = 1.88 × 1042 and 1.48 × 1041 for the amination of primary and secondary alcohols, respectively). This biocatalytic network possesses elevated atom efficiency, since the reaction buffer (ammonium formate) is both the aminating agent and the source of reducing equivalents. Additionally, only dioxygen is needed, whereas water and carbonate are the by-products. For the oxidative step, we have employed three variants of the NADP-dependent alcohol dehydrogenase from Thermoanaerobacter ethanolicus and we have elucidated the origin of the stereoselective properties of these variants with the aid of in silico computational models.
Knaus, Tanja,Cariati, Luca,Masman, Marcelo F,Mutti, Francesco G.
p. 8313 - 8325
(2017/10/19)

MOF-derived cobalt nanoparticles catalyze a general synthesis of amines
The development of base metal catalysts for the synthesis of pharmaceutically relevant compounds remains an important goal of chemical research. Here, we report that cobalt nanoparticles encapsulated by a graphitic shell are broadly effective reductive amination catalysts. Their convenient and practical preparation entailed template assembly of cobaltdiamine- dicarboxylic acid metal organic frameworks on carbon and subsequent pyrolysis under inert atmosphere.The resulting stable and reusable catalysts were active for synthesis of primary, secondary, tertiary, and N-methylamines (more than 140 examples).The reaction couples easily accessible carbonyl compounds (aldehydes and ketones) with ammonia, amines, or nitro compounds, and molecular hydrogen under industrially viable and scalable conditions, offering cost-effective access to numerous amines, amino acid derivatives, and more complex drug targets.
Jagadeesh, Rajenahally V.,Murugesan, Kathiravan,Alshammari, Ahmad S.,Neumann, Helfried,Pohl, Marga-Martina,Radnik, J?rg,Beller, Matthias
p. 326 - 332
(2017/09/28)

Production of Primary Amines by Reductive Amination of Biomass-Derived Aldehydes/Ketones
Transformation of biomass into valuable nitrogen-containing compounds is highly desired, yet limited success has been achieved. Here we report an efficient catalyst system, partially reduced Ru/ZrO2, which could catalyze the reductive amination of a variety of biomass-derived aldehydes/ketones in aqueous ammonia. With this approach, a spectrum of renewable primary amines was produced in good to excellent yields. Moreover, we have demonstrated a two-step approach for production of ethanolamine, a large-market nitrogen-containing chemical, from lignocellulose in an overall yield of 10 %. Extensive characterizations showed that Ru/ZrO2-containing multivalence Ru association species worked as a bifunctional catalyst, with RuO2 as acidic promoter to facilitate the activation of carbonyl groups and Ru as active sites for the subsequent imine hydrogenation.
Liang, Guanfeng,Wang, Aiqin,Li, Lin,Xu, Gang,Yan, Ning,Zhang, Tao
supporting information
p. 3050 - 3054
(2017/03/14)

But-2-ene-1,4-diamine and But-2-ene-1,4-diol as Donors for Thermodynamically Favored Transaminase- and Alcohol Dehydrogenase-Catalyzed Processes
Both cis- and trans-but-2-ene-1,4-diamines have been prepared and efficiently applied as sacrificial cosubstrates in enzymatic transamination reactions. The best results were obtained with the cis-diamine. The thermodynamic equilibrium of the stereoselective transamination process is shifted to the amine formation due to tautomerization of 5H-pyrrole into 1H-pyrrole, achieving high conversions (78–99%) and enantiomeric excess (up to >99%) by using a small excess of the amine donor. Furthermore, when the reaction proceeded, a strong coloration was observed due to polymerization of 1H-pyrrole. A structurally related compound, cis-but-2-ene-1,4-diol, has been utilized as cosubstrate in different alcohol dehydrogenase (ADH)-mediated bioreductions. In this case, high conversions (91–99%) were observed due to a lactonization process. Both strategies are convenient from both synthetic and atom economy points of view in the production of valuable optically active products. (Figure presented.).
Martínez-Montero, Lía,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
supporting information
p. 1618 - 1624
(2016/10/13)

CATALYST COMPOUNDS
The present invention relates to an iridium-based catalyst compound for hydrogenating reducible moieties, especially imines and iminiums, the catalyst compounds being defined by the formulas: where ring B is either itself polycyclic, or ring B together with R is polycyclic. The catalysts of the invention are particularly effective in reductive amination procedures 10 which involve the in situ generation of the imine or iminium under reductive hydrogenative conditions.
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Paragraph 0314; 0322

(2015/03/28)

Asymmetric Biocatalytic Amination of Ketones at the Expense of NH3 and Molecular Hydrogen
A biocatalytic system is presented for the stereoselective amination of ketones at the expense of NH3 and molecular hydrogen. By using a NAD+-reducing hydrogenase, an alanine dehydrogenase, and a suitable ω-transaminase, the R- as well as the S-enantiomer of various amines could be prepared with up to >99% ee and 98% conversion. (Chemical Equation Presented).
Holzer, Anja K.,Hiebler, Katharina,Mutti, Francesco G.,Simon, Robert C.,Lauterbach, Lars,Lenz, Oliver,Kroutil, Wolfgang
supporting information
p. 2431 - 2433
(2015/06/02)

Conversion of alcohols to enantiopure amines through dual-enzyme hydrogen-borrowing cascades
α-Chiral amines are key intermediates for the synthesis of a plethora of chemical compounds at industrial scale. We present a biocatalytic hydrogen-borrowing amination of primary and secondary alcohols that allows for the efficient and environmentally benign production of enantiopure amines. The method relies on a combination of two enzymes: an alcohol dehydrogenase (from Aromatoleum sp., Lactobacillus sp., or Bacillus sp.) operating in tandem with an amine dehydrogenase (engineered from Bacillus sp.) to aminate a structurally diverse range of aromatic and aliphatic alcohols, yielding up to 96% conversion and 99% enantiomeric excess. Primary alcohols were aminated with high conversion (up to 99%). This redox self-sufficient cascade possesses high atom efficiency, sourcing nitrogen from ammonium and generating water as the sole by-product.
Mutti, Francesco G.,Knaus, Tanja,Scrutton, Nigel S.,Breuer, Michael,Turner, Nicholas J.
p. 1525 - 1529
(2015/10/05)

Selective synthesis of primary amines by reductive amination of ketones with ammonia over supported Pt catalysts
Supported platinum catalysts are studied for the reductive amination of ketones under ammonia and hydrogen. For a model reaction with 2-adamantanone, Pt-loaded MoOx/TiO2 (Pt-MoOx/TiO2) shows the highest yield of primary amine. The catalyst is effective for the selective transformation of various aliphatic and aromatic ketones to the corresponding primary amines, which demonstrates the first example of the selective synthesis of primary amines by this reaction. The yield of the amine increases with increase in the negative shift of the C￡O stretching band in the infrared spectra of adsorbed acetone on the catalysts, suggesting that Lewis acid sites on the support material play an important role in this catalytic system.
Nakamura, Yoichi,Kon, Kenichi,Touchy, Abeda Sultana,Shimizu, Ken-Ichi,Ueda, Wataru
p. 921 - 924
(2015/03/18)

Broadening the chemical scope of laccases: Selective deprotection of N-benzyl groups
Laccase from Trametes versicolor together with TEMPO has been found to be a very efficient system to deprotect N-benzylated primary amines, differing from previously described methods since it uses oxygen as a mild oxidant in aqueous medium. Chemoselective removal of the benzyl group was achieved with excellent yields when secondary amines and alcohol moieties were also present.
Martínez-Montero, Lía,Díaz-Rodríguez, Alba,Gotor, Vicente,Gotor-Fernández, Vicente,Lavandera, Iván
supporting information
p. 2794 - 2798
(2015/05/27)

N-alkylation of ammonia and amines with alcohols catalyzed by Ni-loaded CaSiO3
Nickel nanoparticles loaded onto calcium silicate (Ni/CaSiO3) have been prepared by ion-exchange method followed by in situ H 2-reduction of the calcined precursor. Ni/CaSiO3 was found to be effective for the catalytic direct synthesis of primary amines from alcohols and NH3 under relatively mild conditions. Various aliphatic alcohols are tolerated, and the turnover number (TON) was higher than those of Ru-based homogeneous catalysts. The catalyst was recoverable and was reused. Effects of the surface oxidation states and particle size of Ni on the catalytic activity were studied by infrared (IR) investigation of the states of adsorbed CO and transmission electron microscopy (TEM). It is clarified that the surface Ni0 sites on small (3 nm) sized Ni nanoparticles are the catalytically active species. Ni/CaSiO3 was also effective for the alkylation of anilines and aliphatic amines with various alcohols (benzyl and aliphatic alcohols) under additive free conditions; primary amines were converted into secondary amines and secondary amines into tertiary amines.
Shimizu, Ken-Ichi,Kanno, Shota,Kon, Kenichi,Hakim Siddiki,Tanaka, Hideyuki,Sakata, Yoshihisa
p. 134 - 138
(2014/06/09)

Primary amines by transfer hydrogenative reductive amination of ketones by using cyclometalated IrIII catalysts
Cyclometalated iridium complexes are found to be versatile catalysts for the direct reductive amination (DRA) of carbonyls to give primary amines under transfer-hydrogenation conditions with ammonium formate as both the nitrogen and hydrogen source. These complexes are easy to synthesise and their ligands can be easily tuned. The activity and chemoselectivity of the catalyst towards primary amines is excellent, with a substrate to catalyst ratio (S/C) of 1000 being feasible. Both aromatic and aliphatic primary amines were obtained in high yields. Moreover, a first example of homogeneously catalysed transfer-hydrogenative DRA has been realised for β-keto ethers, leading to the corresponding β-amino ethers. In addition, non-natural α-amino acids could also be obtained in excellent yields with this method. Reduce the work! A broad range of ketones have been successfully aminated to afford primary amines under transfer-hydrogenation conditions by using ammonium formate as the amine source and 0.1 mol % of a cyclometalated IrIII catalyst (see scheme). Copyright
Talwar, Dinesh,Salguero, Noemi Poyatos,Robertson, Craig M.,Xiao, Jianliang
supporting information
p. 245 - 252
(2014/01/17)

CATALYST COMPOUNDS
The present invention relates to an iridium-based catalyst compound for hydrogenating reducible moieties, especially imines and iminiums, the catalyst compounds being defined by the formulas: where ring B is either itself polycyclic, or ring B together with R is polycyclic. The catalysts of the invention are particularly effective in reductive amination procedures 10 which involve the in situ generation of the imine or iminium under reductive hydrogenative conditions.
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Paragraph 00163; 00171

(2013/11/05)

Connecting Unexplored Protein Crystal Structures to Enzymatic Function
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Steffen-Munsberg, Fabian,Vickers, Clare,Thontowi, Ahmad,Schaetzle, Sebastian,Tumlirsch, Tony,SvedendahlHumble, Maria,Land, Henrik,Berglund, Per,Bornscheuer, Uwe T.,Hoehne, Matthias
p. 150 - 153
(2013/03/13)

Heterogeneous Ni catalyst for direct synthesis of primary amines from alcohols and ammonia
This paper reports the synthesis of primary amines from alcohols and NH3 by an Al2O3-supported Ni nanoparticle catalyst as the first example of heterogeneous and noble-metal-free catalytic system for this reaction without additional hydrogen sources under relatively mild conditions. Various aliphatic alcohols are tolerated, and turnover numbers were higher than those of Ru-based homogeneous catalysts. The catalyst was recoverable and was reused. The effects of the Ni oxidation states and the acid-base nature of support oxides on the catalytic activity are studied. It is clarified that the surface metallic Ni sites are the catalytically active species, and the copresence of acidic and basic sites on the support surface is also indispensable for this catalytic system.
Shimizu, Ken-Ichi,Kon, Kenichi,Onodera, Wataru,Yamazaki, Hiroshi,Kondo, Junko N.
p. 112 - 117
(2013/03/29)

PROCESS FOR THE DIRECT AMINATION OF SECONDARY ALCOHOLS WITH AMMONIA TO GIVE PRIMARY AMINES
The invention relates to a process for preparing primary amines which comprises the process steps A) provision of a solution of a secondary alcohol in a fluid, nongaseous phase,B) contacting of the phase with free ammonia and/or at least one ammonia-releasing compound and a homogeneous catalyst and optionallyC) isolation of the primary amine formed in process step B), characterized in that the volume ratio of the volume of the liquid phase to the volume of the gas phase in process step B is greater than or equal to 0.25, and/or in that the ammonia is used in process step B) in a molar ratio based on the hydroxyl groups in the secondary alcohol of at least 5:1.
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Paragraph 0083

(2013/07/05)

Utilization of common ligands for the ruthenium-catalyzed amination of alcohols
Simultaneous presence of bidentate phosphines with surprisingly simple structure and of the ligand triphenylphosphine were revealed as structural characteristics of new Ru catalysts for the selective conversion of primary and secondary alcohols and diols into their corresponding primary amines and diamines (see scheme). Copyright
Baumann, Wolfgang,Spannenberg, Anke,Pfeffer, Jan,Haas, Thomas,Koeckritz, Angela,Martin, Andreas,Deutsch, Jens
supporting information
p. 17702 - 17706
(2014/01/17)

PROCESS FOR THE DIRECT AMINATION OF ALCOHOLS USING AMMONIA TO FORM PRIMARY AMINES BY MEANS OF A XANTPHOS CATALYST SYSTEM
The present invention relates to a chemocatalytic liquid-phase process for the direct one-stage amination of alcohols to primary amines by means of ammonia in high yields using a catalyst system containing at least one transition metal compound and a xantphos ligand.
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Paragraph 0060

(2014/01/08)

Nickel nanoparticles as racemization catalysts for primary amines
By combining bases that are known to racemize benzylic amines with a nickel(II) salt, active nickel nanoparticles were obtained that can be used as catalysts in the racemization of both aliphatic and benzylic primary amines. The nanoparticles are stable in the ionic liquid tetrabutylammonium bromide and can complete most racemizations within a few hours with excellent selectivity. The problem of the incompatibility of the strongly reducing racemization catalyst and the enzymatic amine resolution catalyst was overcome by using a two-pot system with a biphasic racemization step. Consecutive contact of a nonane layer that contained the amine with the acylating enzyme and with the racemizing Ni nanoparticles in the ionic liquid allowed the 50 % amide yield limit of a kinetic resolution to be successfully surpassed. Copyright
Geukens, Inge,Plessers, Eva,Seo, Jin Won,De Vos, Dirk E.
p. 2623 - 2628
(2013/07/11)

Step-efficient access to chiral primary amines
Routes to enantioenriched amines are outlined that employ reductive amination and carbanion addition methods. The strategies require either one or two reaction steps from prochiral carbonyl compounds for the synthesis of the corresponding chiral primary amines. Georg Thieme Verlag Stuttgart New York.
Nugent, Thomas C.,Marinova, Sofiya M.
p. 153 - 166
(2013/02/25)

Asymmetric bio-amination of ketones in organic solvents
ω-Transaminases, employed as a lyophilised crude cell-free extract, were successfully employed in organic solvent for the asymmetric amination of ketones without the need for immobilisation. Best activity was found for methyl tert-butyl ether (MTBE) at a water activity of 0.6. The ω-transaminases (9 different enzymes) accepted efficiently 2-propylamine as amine donor when used in the solvent, which is not the case when they are used in aqueous solution. The bio-amination in organic solvent showed several advantages such as higher reaction rates (up to 17-fold), general acceptance of 2-propylamine as amine donor, simple work-up procedure (i.e., no basification and extraction required), easy recycling of the catalyst and lack of substrate inhibition. The biocatalysts maintained their excellent stereoselectivity in MTBE allowing the preparation of optically pure amines (ee >99%) with up to >99% conversion.
Mutti, Francesco G.,Kroutil, Wolfgang
supporting information
p. 3409 - 3413
(2013/02/25)

ω-Transaminase-catalyzed kinetic resolution of chiral amines using l-threonine as an amino acceptor precursor
Kinetic resolution of chiral amines using l-threonine as a cosubstrate was demonstrated by a biocatalytic strategy in which (S)-selective ω-transaminase (ω-TA) was coupled with threonine deaminase (TD), eliminating the need to use an expensive keto acid as an amino acceptor. The coupled enzyme reaction enabled simultaneous production of enantiopure (R)-amine and l-homoalanine which are pharmaceutically important building blocks. To extend the versatility of this strategy to production of both enantiomers of chiral amines, (R)-selective ω-TA coupled with TD was employed to produce (S)-amine.
Malik, M. Shaheer,Park, Eul-Soo,Shin, Jong-Shik
supporting information; experimental part
p. 2137 - 2140
(2012/09/25)

Sequential reductive amination-hydrogenolysis: A one-pot synthesis of challenging chiral primary amines
Difficult-to-access chiral primary amines were formed in good to high yield and ee using a rare example of a one-pot synthesis from prochiral ketones (sequential reductive amination-hydrogenloysis). As a highlight we also demonstrate a one-pot reductive amination-hydrogenolysis-reductive amination (five reactions) of ortho-methoxyacetophenone resulting in the chiral diamine 1-(2-methoxyphenyl)ethyl-(2-pyridylmethyl)-amine (4) (58% overall yield, >99% ee), a new organocatalyst for aqueous enantioselective aldol reactions. Copyright
Nugent, Thomas C.,Negru, Daniela E.,El-Shazly, Mohamed,Hu, Dan,Sadiq, Abdul,Bibi, Ahtaram,Umar, M. Naveed
p. 2085 - 2092
(2011/10/19)

Stereoselectivity of four (R)-selective transaminases for the asymmetric amination of ketones
Four (R)-ω-transaminases originating from Hyphomonas neptunium (HN-ωTA), Aspergillus terreus (AT-ωTA) and Arthrobacter sp. (ArR-ωTA), as well as an evolved transaminase (ArRmut11-ωTA) were successfully employed for the amination of prochiral ketones leading to optically pure (R)-amines. The first three transaminases displayed perfect stereoselectivity for the amination of all substrates tested (ee >99%). Furthermore, the transaminase AT-ωTA led in most cases to better conversion than ArR-ωTA and HN-ωTA using D-alanine as amine donor. α-Tetralone, which was the only substrate not accepted by HN-ωTA, ArR-ωTA, and AT-ωTA, was successfully transformed with perfect enantioselectivity (ee >99%) into the corresponding optically pure amine employing the variant ArRmut11-ωTA. Copyright
Mutti, Francesco G.,Fuchs, Christine S.,Pressnitz, Desiree,Sattler, Johann H.,Kroutil, Wolfgang
experimental part
p. 3227 - 3233
(2012/01/03)

A direct and stereoretentive synthesis of amides from cyclic alcohols
Chlorosulfites prepared in situ using thionyl chloride react with nitrile complexes of titanium(IV) fluoride to give a one-pot conversion of alcohols into amides. For the first time, amides are obtained from cyclic alcohols with stereoretention. Critical to the design of these new TiIV reactions has been the use of little-explored TiIV nitrile complexes that are thought to chelate chlorosulfites in the transition state tocreate a carbocation that is rapidly captured by the nitrile nucleophile through a front-side attack mechanism.
Mondal, Deboprosad,Bellucci, Luca,Lepore, Salvatore D.
supporting information; experimental part
p. 7057 - 7061
(2012/01/03)

Chemoenzymatic dynamic kinetic resolution of primary amines catalyzed by CAL-B at 38-40°c
The (R)-selective chemoenzymatic dynamic kinetic resolution of primary amines was performed at 38-40 °C in MTBE, in good to high yields and with high enantiomeric excesses. These reactions associating CAL-B to octanethiol as radical racemizing agent were carried out in the presence of methyl β-methoxy propanoate as acyl donor, under photochemical irradiation at 350 nm in glassware.
Poulhes, Florent,Vanthuyne, Nicolas,Bertrand, Michele P.,Gastaldi, Stephane,Gil, Gerard
experimental part
p. 7281 - 7286
(2011/10/10)

Asymmetric intermolecular hydroamination of unactivated alkenes with simple amines
A hard nut to crack: The asymmetric intermolecular Markovnikov addition of simple amines to unactivated alkenes can be achieved utilizing binaphtholate rare-earth-metal catalysts with up to 61% ee and 73% de in the case where R 2 contains a stereogenic center.
Reznichenko, Alexander L.,Nguyen, Hiep N.,Hultzsch, Kai C.
supporting information; experimental part
p. 8984 - 8987
(2011/02/21)

Direct amination of secondary alcohols using ammonia
Hydrogen shuttle: For the first time secondary alcohols and ammonia can be directly converted into primary amines with a selectivity of up to 99% by using a simple ruthenium/phosphine catalyst (see scheme; R1, R2= alkyl, aryl, alkenyl; M=[Ru3(CO)12]; and L=phosphine ligand).
Pingen, Dennis,Mueller, Christian,Vogt, Dieter
supporting information; experimental part
p. 8130 - 8133
(2011/02/22)

An efficient and general synthesis of primary amines by ruthenium-catalyzed amination of secondary alcohols with ammonia
Atom efficiency and selectivity are the key features of the first homogeneously catalyzed amination of secondary alcohols with ammonia to give the corresponding primary amines (see scheme). This novel amination method relies on the commercially available catalyst [Ru3(CO)12]/ cataCXium PCy and does not require any additional source of hydrogen.
Imm, Sebastian,Neubert, Lorenz,Neumann, Helfried,Beller, Matthias
supporting information; experimental part
p. 8126 - 8129
(2011/02/22)

Formal asymmetric biocatalytic reductive amination
All for one: A combination of three biocatalysts (ω-transaminase, alanine dehydrogenase, and an enzyme such as formate dehydrogenase for cofactor recycling) catalyze a cascade to achieve the asymmetric transformation of a ketone into a primary α-chiral unprotected amine through a formal stereoselective reductive amination (see scheme). Only ammonia and the reducing agent (formate) are consumed during this reaction. (Chemical Equation Presented).
Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Guebitz, Georg M.,Rozzell, David,Kroutil, Wolfgang
supporting information; experimental part
p. 9337 - 9340
(2009/05/15)

Asymmetric synthesis of optically pure pharmacologically relevant amines employing ω-transaminases
Various ω-transaminases were tested for the synthesis of enantiomerically pure amines from the corresponding ketones employing D- or L-alanine as amino donor and lactate dehydrogenase to remove the side-product pyruvate to shift the unfavourable reaction equilibrium to the product side. Both enantiomers, (R)- and (S)-amines, could be prepared with up to 99% ee and >99% conversions within 24 h at 50 mM substrate concentration. The activity and stereoselectivity of the amination reaction depended on the ω-transaminase and substrate employed; furthermore the co-solvent significantly influenced both the stereoselectivity and activity of the transaminases. Best results were obtained by employing ATA-117 to obtain the (R)-enantiomer and ATA-113 or ATA-103 to access the (S)-enantiomer with 15% v v-1 DMSO.
Koszelewski, Dominik,Lavandera, Ivan,Clay, Dorina,Rozzell, David,Kroutil, Wolfgang
scheme or table
p. 2761 - 2766
(2009/10/06)