Reductive amination

Last updated

Contents

Reductive amination
Reaction type Coupling reaction
Identifiers
RSC ontology ID RXNO:0000335

Reductive amination (also known as reductive alkylation) is a form of amination that converts a carbonyl group to an amine via an intermediate imine. The carbonyl group is most commonly a ketone or an aldehyde. It is a common method to make amines and is widely used in green chemistry since it can be done catalytically in one-pot under mild conditions. In biochemistry, dehydrogenase enzymes use reductive amination to produce the amino acid glutamate. Additionally, there is ongoing research on alternative synthesis mechanisms with various metal catalysts which allow the reaction to be less energy taxing, and require milder reaction conditions. Investigation into biocatalysts, such as imine reductases, have allowed for higher selectivity in the reduction of chiral amines which is an important factor in pharmaceutical synthesis. [1]

RedveAm.svg

Reaction process

Reductive amination occurs between a carbonyl such as an aldehyde or ketone and an amine in the presence of a reducing agent. [2] The reaction conditions are neutral or weakly acidic. [2]

The intermediates of a reductive amination reaction. Reaction scheme of reductive amination.png
The intermediates of a reductive amination reaction.

Reaction Steps

  1. The nucelophilic amine reacts at the carbon of the carbonyl group to form a hemiaminal species
  2. reversible loss of one molecule of water from the hemiaminal species by alkylimino-de-oxo-bisubstitution to form the imine intermediate. [3] The equilibrium between aldehyde/ketone and imine is shifted toward imine formation by dehydration. [2]
  3. The intermediate imine can be isolated or reacted in-situ with a suitable reducing agent (e.g., sodium borohydride) to produce the amine product. [2] Intramolecular reductive amination can also occur to afford a cyclic amine product if the amine and carbonyl are on the same molecule of starting material. [4]

There are two ways to conduct a reductive amination reaction: direct and indirect. [2]

Direct Reductive Amination

In a direct reaction, the carbonyl and amine starting materials and the reducing agent are combined and the reductions are done sequentially. [2] These are often one-pot reactions since the imine intermediate is not isolated before the final reduction to the product. [2] Instead, as the reaction proceeds, the imine becomes favoured for reduction over the carbonyl starting material. [2] The two most common methods for direct reductive amination are hydrogenation with catalytic platinum, palladium, or nickel catalysts and the use of hydride reducing agents like cyanoborohydride (NaBH3CN). [2]

Indirect Reductive Amination

Indirect reductive amination, also called a stepwise reduction, isolates the imine intermediate. [2] In a separate step, the isolated imine intermediate is reduced to form the amine product. [2]

Designing a reductive amination reaction

There are many considerations to be made when designing a reductive amination reaction. [5]

  1. Chemoselectivity issues may arise since the carbonyl group can also be reduced.
  2. The reaction between the carbonyl and amine are in equilibrium, favouring the carbonyl unless water is removed from the system.
  3. reduction-sensitive intermediates may form in the reaction which can affect chemoselectivity.
  4. The amine substrate, imine intermediate, or amine product might deactivate the catalyst.
  5. Acyclic imines have E/Z isomers. This makes it difficult to create enantiopure chiral compounds through stereoselective reductions.

To solve the last issue, asymmetric reductive amination reactions can be used to synthesize an enantiopure product of chiral amines. [5] In asymmetric reductive amination, a carbonyl that can be converted from achiral to chiral is used. [6] The carbonyl undergoes condensation with an amine in the presence of H2 and a chiral catalyst to form the imine intermediate, which is then reduced to form the amine. [6] However, this method is still limiting to synthesize primary amines which are non-selective and prone to overalkylation. [6]

Common reducing agents

Palladium Hydride

Palladium hydride (H2/Pd) is a versatile reducing agent commonly used in reductive amination reactions. Its catalytic efficiency stems from the ability of palladium to adsorb hydrogen gas, forming active hydride species. These hydrides facilitate the reduction of imines or iminium ions—key intermediates in reductive amination—into secondary or tertiary amines. This reaction typically occurs under mild conditions with excellent selectivity, which often makes H2/Pd the first choice for synthesizing amines in pharmaceuticals and fine chemicals. Additionally, H2/Pd is compatible with a wide range of functional groups, further enhancing its utility in complex organic synthesis.

Sodium Borohydride

Sodium Borohydride (NaBH4) reduces both imines and carbonyl groups. [3] However, it is not very selective and can reduce other reducible functional groups present in the reaction. [3] To ensure that this does not occur, reagents with weak electrophilic carbonyl groups, poor nucleophilic amines and sterically hindered reactive centres should not be used, as these properties do not favour the reduction of the carbonyl to form an imine and increases the chance that other functional groups will be reduced instead. [3]

Sodium Cyanoborohydride

Sodium cyanoborohydride (NaBH3CN) is soluble in hydroxylic solvents, stable in acidic solutions, and has different selectivities depending on the pH. [2] At low pH values, it efficiently reduces aldehydes and ketones. [7] As the pH increases, the reduction rate slows and instead, the imine intermediate becomes preferential for reduction. [7] For this reason, NaBH3CN is an ideal reducing agent for one-pot direct reductive amination reactions that don't isolate the intermediate imine. [2]

When used as a reducing agent, NaBH3CN can release toxic by-products like HCN and NaCN during work up. [2]

Sodium Triacetoxyborohydride

Sodium triacetoxyborohydride (STAB, NaBH(OAc)3) is a common reducing agent for reductive aminations. STAB selectively reduces the imine intermediate formed through dehydration of the molecule. [8] STAB is a weaker reductant than NaBH4, and can preferentially reduce the imine group in the presence of other reduction-sensitive functional groups. While STAB has also been reported as a selective reducing agent for aldehydes in the presence of keto groups, standard reductive amination reaction conditions greatly favour imine reduction to form an amine. [9] [10]

Table 1. Physical and Chemical Characteristics of Common Reducing Agents [11]

H2/PdNaBH4NaBH(OAc) 3NaBH3CNCO/Rh
SelectivityLowLowHighHighHigh
Atom economyHighSolid wastesSolid wastesSolid wastesHigh
Work upRequiredNot requiredNot requiredNot requiredRequired
FlammabilityHighLowHighHighHigh
Sensitivity to H2O, O2LowHighHighHighLow
ToxicityNoneHigh, CarcinogenLowHighHigh

The reductive amination reaction is related to the Eschweiler–Clarke reaction, in which amines are methylated to tertiary amines, the Leuckart–Wallach reaction, [12] and other amine alkylation methods such as the Mannich reaction and Petasis reaction.

A classic named reaction is the Mignonac reaction (1921) [13] involving reaction of a ketone with ammonia over a nickel catalyst. An example of this reaction is the synthesis of 1-phenylethylamine from acetophenone: [14]

Reductive amination acetophenone ammonia Reductive amination acetophenone ammonia.svg
Reductive amination acetophenone ammonia

Additionally, many systems catalyze reductive aminations with hydrogenation catalysts. [15] Generally, catalysis is preferred to stoichiometric reactions as they may improve reaction efficiency and atom economy, and produce less waste. [16] These reactions can utilize homogeneous or heterogeneous catalyst systems. [15] These systems provide alternative synthesis routes which are efficient, require fewer volatile reagents and are redox-economical. [15] [17] As well, this method can be used in the reduction of alcohols, along with aldehydes and ketones to form the amine product. [15] One example of a heterogeneous catalytic system is the Ni-catalyzed reductive amination of alcohols. [15] [18] Nickel is commonly used as a catalyst for reductive amination because of its abundance and relatively good catalytic activity. [15] [19]

First, the nickel metal dehydrogenates the alcohol to form a ketone and Ni-H complex. Then, the ketone reacts with ammonia to form an imine. Finally, the imine reacts with Ni-H to regenerate catalyst and form primary amine. Reaction Scheme of Ni-Catalyzed reductive amination.png
First, the nickel metal dehydrogenates the alcohol to form a ketone and Ni-H complex. Then, the ketone reacts with ammonia to form an imine. Finally, the imine reacts with Ni-H to regenerate catalyst and form primary amine.

An example of a homogeneous catalytic system is the reductive amination of ketones done with an iridium catalyst. [20] Homogenous Iridium (III) catalysts have been shown to be effective in the reductive amination of carboxylic acids, which in the past has been more difficult than aldehydes and ketones. [16] Homogeneous catalysts are often favored because they are more environmentally and economically friendly compared to most heterogeneous systems. [15]

Ketone reacting with ammonium formate, catalyzed by iridium catalyst, to form primary amine. General Reaction Scheme of Iridium Catalyzed RA.png
Ketone reacting with ammonium formate, catalyzed by iridium catalyst, to form primary amine.

In industry, tertiary amines such as triethylamine and diisopropylethylamine are formed directly from ketones with a gaseous mixture of ammonia and hydrogen and a suitable catalyst.

In green chemistry

Reductive amination is commonly used over other methods for introducing amines to alkyl substrates, such as SN2-type reactions with halides, since it can be done in mild conditions and has high selectivity for nitrogen-containing compounds. [21] [22] Reductive amination can occur sequentially in one-pot reactions, which eliminates the need for intermediate purifications and reduces waste. [21] Some multistep synthetic pathways have been reduced to one step through one-pot reductive amination. [21] This makes it a highly appealing method to produce amines in green chemistry.

Biochemistry

In biochemistry, dehydrogenase enzymes can catalyze the reductive amination of α-keto acids and ammonia to yield α-amino acids. Reductive amination is predominantly used for the synthesis of the amino acid glutamate starting from α-ketoglutarate, while biochemistry largely relies on transamination to introduce nitrogen in the other amino acids. [23] The use of enzymes as a catalyst is advantageous because the enzyme active sites are often stereospecific and have the ability to selectively synthesize a certain enantiomer. [24] This is useful in the pharmaceutical industry, particularly for drug-development, because enantiomer pairs can have different reactivities in the body. [1] [25] Additionally, enzyme biocatalysts are often quite selective in reactivity so they can be used in the presence of other functional groups, without the use of protecting groups. [24] [26] For instance a class of enzymes called imine reductases, IREDs, can be used to catalyze direct asymmetric reductive amination to form chiral amines. [1] [26]

In the critically acclaimed drama Breaking Bad , main character Walter White uses the reductive amination reaction to produce his high purity methamphetamine, relying on phenyl-2-propanone and methylamine.

See also

Related Research Articles

<span class="mw-page-title-main">Hydrogenation</span> Chemical reaction between molecular hydrogen and another compound or element

Hydrogenation is a chemical reaction between molecular hydrogen (H2) and another compound or element, usually in the presence of a catalyst such as nickel, palladium or platinum. The process is commonly employed to reduce or saturate organic compounds. Hydrogenation typically constitutes the addition of pairs of hydrogen atoms to a molecule, often an alkene. Catalysts are required for the reaction to be usable; non-catalytic hydrogenation takes place only at very high temperatures. Hydrogenation reduces double and triple bonds in hydrocarbons.

<span class="mw-page-title-main">Enamine</span> Class of chemical compounds

An enamine is an unsaturated compound derived by the condensation of an aldehyde or ketone with a secondary amine. Enamines are versatile intermediates.

<span class="mw-page-title-main">Imine</span> Organic compound or functional group containing a C=N bond

In organic chemistry, an imine is a functional group or organic compound containing a carbon–nitrogen double bond. The nitrogen atom can be attached to a hydrogen or an organic group (R). The carbon atom has two additional single bonds. Imines are common in synthetic and naturally occurring compounds and they participate in many reactions.

<span class="mw-page-title-main">Organic redox reaction</span> Redox reaction that takes place with organic compounds

Organic reductions or organic oxidations or organic redox reactions are redox reactions that take place with organic compounds. In organic chemistry oxidations and reductions are different from ordinary redox reactions, because many reactions carry the name but do not actually involve electron transfer. Instead the relevant criterion for organic oxidation is gain of oxygen and/or loss of hydrogen. Simple functional groups can be arranged in order of increasing oxidation state. The oxidation numbers are only an approximation:

<span class="mw-page-title-main">Corey–Itsuno reduction</span>

The Corey–Itsuno reduction, also known as the Corey–Bakshi–Shibata (CBS) reduction, is a chemical reaction in which a prochiral ketone is enantioselectively reduced to produce the corresponding chiral, non-racemic alcohol. The oxazaborolidine reagent which mediates the enantioselective reduction of ketones was previously developed by the laboratory of Itsuno and thus this transformation may more properly be called the Itsuno-Corey oxazaborolidine reduction.

In chemistry, transfer hydrogenation is a chemical reaction involving the addition of hydrogen to a compound from a source other than molecular H2. It is applied in laboratory and industrial organic synthesis to saturate organic compounds and reduce ketones to alcohols, and imines to amines. It avoids the need for high-pressure molecular H2 used in conventional hydrogenation. Transfer hydrogenation usually occurs at mild temperature and pressure conditions using organic or organometallic catalysts, many of which are chiral, allowing efficient asymmetric synthesis. It uses hydrogen donor compounds such as formic acid, isopropanol or dihydroanthracene, dehydrogenating them to CO2, acetone, or anthracene respectively. Often, the donor molecules also function as solvents for the reaction. A large scale application of transfer hydrogenation is coal liquefaction using "donor solvents" such as tetralin.

<span class="mw-page-title-main">Sodium cyanoborohydride</span> Chemical compound

Sodium cyanoborohydride is a chemical compound with the formula Na[BH3(CN)]. It is a colourless salt used in organic synthesis for chemical reduction including that of imines and carbonyls. Sodium cyanoborohydride is a milder reductant than other conventional reducing agents.

The Meerwein–Ponndorf–Verley (MPV) reduction in organic chemistry is the reduction of ketones and aldehydes to their corresponding alcohols utilizing aluminium alkoxide catalysis in the presence of a sacrificial alcohol. The advantages of the MPV reduction lie in its high chemoselectivity and its use of a cheap environmentally friendly metal catalyst. MPV reductions have been described as "obsolete" owing to the development of sodium borohydride and related reagents.

In organic chemistry, the Buchwald–Hartwig amination is a chemical reaction for the synthesis of carbon–nitrogen bonds via the palladium-catalyzed coupling reactions of amines with aryl halides. Although Pd-catalyzed C–N couplings were reported as early as 1983, Stephen L. Buchwald and John F. Hartwig have been credited, whose publications between 1994 and the late 2000s established the scope of the transformation. The reaction's synthetic utility stems primarily from the shortcomings of typical methods for the synthesis of aromatic C−N bonds, with most methods suffering from limited substrate scope and functional group tolerance. The development of the Buchwald–Hartwig reaction allowed for the facile synthesis of aryl amines, replacing to an extent harsher methods while significantly expanding the repertoire of possible C−N bond formations.

The Hajos–Parrish–Eder–Sauer–Wiechert and Barbas-List reactions in organic chemistry are a family of proline-catalysed asymmetric aldol reactions.

Asymmetric hydrogenation is a chemical reaction that adds two atoms of hydrogen to a target (substrate) molecule with three-dimensional spatial selectivity. Critically, this selectivity does not come from the target molecule itself, but from other reagents or catalysts present in the reaction. This allows spatial information to transfer from one molecule to the target, forming the product as a single enantiomer. The chiral information is most commonly contained in a catalyst and, in this case, the information in a single molecule of catalyst may be transferred to many substrate molecules, amplifying the amount of chiral information present. Similar processes occur in nature, where a chiral molecule like an enzyme can catalyse the introduction of a chiral centre to give a product as a single enantiomer, such as amino acids, that a cell needs to function. By imitating this process, chemists can generate many novel synthetic molecules that interact with biological systems in specific ways, leading to new pharmaceutical agents and agrochemicals. The importance of asymmetric hydrogenation in both academia and industry contributed to two of its pioneers — William Standish Knowles and Ryōji Noyori — being collectively awarded one half of the 2001 Nobel Prize in Chemistry.

<span class="mw-page-title-main">Oxocarbenium</span>

An oxocarbeniumion is a chemical species characterized by a central sp2-hybridized carbon, an oxygen substituent, and an overall positive charge that is delocalized between the central carbon and oxygen atoms. An oxocarbenium ion is represented by two limiting resonance structures, one in the form of a carbenium ion with the positive charge on carbon and the other in the form of an oxonium species with the formal charge on oxygen. As a resonance hybrid, the true structure falls between the two. Compared to neutral carbonyl compounds like ketones or esters, the carbenium ion form is a larger contributor to the structure. They are common reactive intermediates in the hydrolysis of glycosidic bonds, and are a commonly used strategy for chemical glycosylation. These ions have since been proposed as reactive intermediates in a wide range of chemical transformations, and have been utilized in the total synthesis of several natural products. In addition, they commonly appear in mechanisms of enzyme-catalyzed biosynthesis and hydrolysis of carbohydrates in nature. Anthocyanins are natural flavylium dyes, which are stabilized oxocarbenium compounds. Anthocyanins are responsible for the colors of a wide variety of common flowers such as pansies and edible plants such as eggplant and blueberry.

<span class="mw-page-title-main">Strychnine total synthesis</span>

Strychnine total synthesis in chemistry describes the total synthesis of the complex biomolecule strychnine. The first reported method by the group of Robert Burns Woodward in 1954 is considered a classic in this research field.

In nitrile reduction a nitrile is reduced to either an amine or an aldehyde with a suitable chemical reagent.

<span class="mw-page-title-main">Carbonyl reduction</span> Organic reduction of any carbonyl group by a reducing agent

In organic chemistry, carbonyl reduction is the conversion of any carbonyl group, usually to an alcohol. It is a common transformation that is practiced in many ways. Ketones, aldehydes, carboxylic acids, esters, amides, and acid halides - some of the most pervasive functional groups, -comprise carbonyl compounds. Carboxylic acids, esters, and acid halides can be reduced to either aldehydes or a step further to primary alcohols, depending on the strength of the reducing agent. Aldehydes and ketones can be reduced respectively to primary and secondary alcohols. In deoxygenation, the alcohol group can be further reduced and removed altogether by replacement with H.

In organic chemistry, the Baylis–Hillman, Morita–Baylis–Hillman, or MBH reaction is a carbon-carbon bond-forming reaction between an activated alkene and a carbon electrophile in the presence of a nucleophilic catalyst, such as a tertiary amine or phosphine. The product is densely functionalized, joining the alkene at the α-position to a reduced form of the electrophile.

<span class="mw-page-title-main">Sodium triacetoxyborohydride</span> Chemical compound

Sodium triacetoxyborohydride, also known as sodium triacetoxyhydroborate, commonly abbreviated STAB, is a chemical compound with the formula Na[(CH3COO)3BH]. Like other borohydrides, it is used as a reducing agent in organic synthesis. This colourless salt is prepared by protonolysis of sodium borohydride with acetic acid:

<span class="mw-page-title-main">Hydrogen-bond catalysis</span>

Hydrogen-bond catalysis is a type of organocatalysis that relies on use of hydrogen bonding interactions to accelerate and control organic reactions. In biological systems, hydrogen bonding plays a key role in many enzymatic reactions, both in orienting the substrate molecules and lowering barriers to reaction. The field is relatively undeveloped compared to research in Lewis acid catalysis.

The Crabbé reaction is an organic reaction that converts a terminal alkyne and aldehyde into an allene in the presence of a soft Lewis acid catalyst and secondary amine. Given continued developments in scope and generality, it is a convenient and increasingly important method for the preparation of allenes, a class of compounds often viewed as exotic and synthetically challenging to access.

The ketimine Mannich reaction is an asymmetric synthetic technique using differences in starting material to push a Mannich reaction to create an enantiomeric product with steric and electronic effects, through the creation of a ketimine group. Typically, this is done with a reaction with proline or another nitrogen-containing heterocycle, which control chirality with that of the catalyst. This has been theorized to be caused by the restriction of undesired (E)-isomer by preventing the ketone from accessing non-reactive tautomers. Generally, a Mannich reaction is the combination of an amine, a ketone with a β-acidic proton and aldehyde to create a condensed product in a β-addition to the ketone. This occurs through an attack on the ketone with a suitable catalytic-amine unto its electron-starved carbon, from which an imine is created. This then undergoes electrophilic addition with a compound containing an acidic proton. It is theoretically possible for either of the carbonyl-containing molecules to create diastereomers, but with the addition of catalysts which restrict addition as of the enamine creation, it is possible to extract a single product with limited purification steps and in some cases as reported by List et al.; practical one-pot syntheses are possible. The process of selecting a carbonyl-group gives the reaction a direct versus indirect distinction, wherein the latter case represents pre-formed products restricting the reaction's pathway and the other does not. Ketimines selects a reaction group, and circumvent a requirement for indirect pathways.

References

  1. 1 2 3 Thorpe, Thomas W.; Marshall, James R.; Harawa, Vanessa; Ruscoe, Rebecca E.; Cuetos, Anibal; Finnigan, James D.; Angelastro, Antonio; Heath, Rachel S.; Parmeggiani, Fabio; Charnock, Simon J.; Howard, Roger M.; Kumar, Rajesh; Daniels, David S. B.; Grogan, Gideon; Turner, Nicholas J. (7 April 2022). "Multifunctional biocatalyst for conjugate reduction and reductive amination". Nature. 604 (7904): 86–91. Bibcode:2022Natur.604...86T. doi:10.1038/s41586-022-04458-x. hdl: 11311/1232494 . ISSN   0028-0836. PMID   35388195. S2CID   248001189.
  2. 1 2 3 4 5 6 7 8 9 10 11 12 13 14 Abdel-Magid, Ahmed F.; Carson, Kenneth G.; Harris, Bruce D.; Maryanoff, Cynthia A.; Shah, Rekha D. (1 January 1996). "Reductive Amination of Aldehydes and Ketones with Sodium Triacetoxyborohydride. Studies on Direct and Indirect Reductive Amination Procedures 1". The Journal of Organic Chemistry. 61 (11): 3849–3862. doi:10.1021/jo960057x. ISSN   0022-3263. PMID   11667239.
  3. 1 2 3 4 Tripathi, Rama P.; Verma, Shyam S.; Pandey, Jyoti; Tiwari, Vinod K. (2008). "Recent Development on Catalytic Reductive Amination and Applications". Current Organic Chemistry. 12 (13): 1093–1115. doi:10.2174/138527208785740283.
  4. ↑ Sawant, Rajiv T.; Waghmode, Suresh B. (13 March 2010). "Intramolecular reductive amination strategy to the synthesis of (R)-N-Boc-2-hydroxymethylmorpholine, N-(3,4-dichlorobenzyl)(R)-2-hydroxymethylmorpholine, and (R)-2-benzylmorpholine". Tetrahedron. 66 (11): 2010–2014. doi:10.1016/j.tet.2010.01.047. ISSN   0040-4020.
  5. 1 2 Wang, Chao; Xiao, Jianliang (2013), Li, Wei; Zhang, Xumu (eds.), "Asymmetric Reductive Amination", Stereoselective Formation of Amines, vol. 343, Berlin, Heidelberg: Springer Berlin Heidelberg, pp. 261–282, doi:10.1007/128_2013_484, ISBN   978-3-642-53928-2, PMID   24158548 , retrieved 6 November 2023
  6. 1 2 3 Reshi, Noor U Din; Saptal, Vitthal B.; Beller, Matthias; Bera, Jitendra K. (19 November 2021). "Recent Progress in Transition-Metal-Catalyzed Asymmetric Reductive Amination". ACS Catalysis. 11 (22): 13809–13837. doi:10.1021/acscatal.1c04208. ISSN   2155-5435. S2CID   240250685.
  7. 1 2 Borch, Richard F.; Durst, H. Dupont (July 1969). "Lithium cyanohydridoborate, a versatile new reagent". Journal of the American Chemical Society. 91 (14): 3996–3997. doi:10.1021/ja01042a078. ISSN   0002-7863.
  8. ↑ Abdel-Magid, Ahmed F.; Carson, Kenneth G.; Harris, Bruce D.; Maryanoff, Cynthia A.; Shah, Rekha D. (1 January 1996). "Reductive Amination of Aldehydes and Ketones with Sodium Triacetoxyborohydride. Studies on Direct and Indirect Reductive Amination Procedures1". The Journal of Organic Chemistry. 61 (11): 3849–3862. doi:10.1021/jo960057x. ISSN   0022-3263.
  9. ↑ Abdel-Magid, Ahmed F.; Mehrman, Steven J. (1 September 2006). "A Review on the Use of Sodium Triacetoxyborohydride in the Reductive Amination of Ketones and Aldehydes". Organic Process Research & Development. 10 (5): 971–1031. doi:10.1021/op0601013. ISSN   1083-6160.
  10. ↑ Oliphant, Shannon J.; Morris, Robert H. (30 August 2022). "Density Functional Theory Study on the Selective Reductive Amination of Aldehydes and Ketones over Their Reductions to Alcohols Using Sodium Triacetoxyborohydride". ACS Omega. 7 (34): 30554–30564. doi:10.1021/acsomega.2c04056.
  11. ↑ Podyacheva, Evgeniya; Afanasyev, Oleg I.; Tsygankov, Alexey A.; Makarova, Maria; Chusov, Denis (2019-07). "Hitchhiker's Guide to Reductive Amination". Synthesis. 51 (13): 2667–2677. doi:10.1055/s-0037-1611788. ISSN   0039-7881.{{cite journal}}: Check date values in: |date= (help)
  12. ↑ George, Frederick & Saunders, Bernard (1960). Practical Organic Chemistry, 4th Ed. London: Longman. p. 223. ISBN   9780582444072.
  13. ↑ Mignonac, Georges (1921). "Nouvelle méthode générale de préparation des amines à partir des aldéhydes ou des cétones" [New general method for preparation of amines from aldehydes or ketones]. Comptes rendus (in French). 172: 223.
  14. ↑ Robinson, John C.; Snyder, H. R. (1955). "α-Phenylethylamine". Organic Syntheses . doi:10.1002/0471264180.os023.27 ; Collected Volumes, vol. 3, p. 717.
  15. 1 2 3 4 5 6 7 Huang, Hao; Wei, Yuejun; Cheng, Yuran; Xiao, Shuwen; Chen, Mingchih; Wei, Zuojun (7 October 2023). "The Acquisition of Primary Amines from Alcohols through Reductive Amination over Heterogeneous Catalysts". Catalysts. 13 (10): 1350. doi: 10.3390/catal13101350 . ISSN   2073-4344.
  16. 1 2 Ouyang, Lu; Miao, Rui; Yang, Zhanhui; Luo, Renshi (1 February 2023). "Iridium-catalyzed reductive amination of carboxylic acids". Journal of Catalysis. 418: 283–289. doi:10.1016/j.jcat.2023.01.030. ISSN   0021-9517.
  17. ↑ Burns, Noah Z.; Baran, Phil S.; Hoffmann, Reinhard W. (6 April 2009). "Redox Economy in Organic Synthesis". Angewandte Chemie International Edition. 48 (16): 2854–2867. doi:10.1002/anie.200806086. ISSN   1433-7851. PMID   19294720.
  18. ↑ Kalbasi, Roozbeh Javad; Mazaheri, Omid (2015). "Synthesis and characterization of hierarchical ZSM-5 zeolite containing Ni nanoparticles for one-pot reductive amination of aldehydes with nitroarenes". Catalysis Communications. 69: 86–91. doi:10.1016/j.catcom.2015.05.016.
  19. ↑ Chernyshev, Victor M.; Ananikov, Valentine P. (21 January 2022). "Nickel and Palladium Catalysis: Stronger Demand than Ever". ACS Catalysis. 12 (2): 1180–1200. doi:10.1021/acscatal.1c04705. ISSN   2155-5435. S2CID   245795966.
  20. ↑ Tanaka, Kouichi; Miki, Takashi; Murata, Kunihiko; Yamaguchi, Ayumi; Kayaki, Yoshihito; Kuwata, Shigeki; Ikariya, Takao; Watanabe, Masahito (6 September 2019). "Reductive Amination of Ketonic Compounds Catalyzed by Cp*Ir(III) Complexes Bearing a Picolinamidato Ligand". The Journal of Organic Chemistry. 84 (17): 10962–10977. doi:10.1021/acs.joc.9b01565. ISSN   0022-3263. PMID   31362498. S2CID   199000460.
  21. 1 2 3 Van Praet, Sofie; Preegel, Gert; Rammal, Fatima; Sels, Bert F. (12 May 2022). "One-Pot Consecutive Reductive Amination Synthesis of Pharmaceuticals: From Biobased Glycolaldehyde to Hydroxychloroquine". ACS Sustainable Chemistry & Engineering. 10 (20): 6503–6508. doi:10.1021/acssuschemeng.2c00570. ISSN   2168-0485. S2CID   248767494.
  22. ↑ He, Jian; Chen, Lulu; Liu, Shima; Song, Ke; Yang, Song; Riisager, Anders (2020). "Sustainable access to renewable N-containing chemicals from reductive amination of biomass-derived platform compounds". Green Chemistry. 22 (20): 6714–6747. doi:10.1039/d0gc01869d. ISSN   1463-9262. S2CID   225001665.
  23. ↑ Metzler, D. E. "Biochemistry—The Chemical Reactions of Living Cells, Vol. 2" 2nd Ed. Academic Press: San Diego, 2003.
  24. 1 2 Wohlgemuth, Roland; Littlechild, Jennifer (22 July 2022). "Complexity reduction and opportunities in the design, integration and intensification of biocatalytic processes for metabolite synthesis". Frontiers in Bioengineering and Biotechnology. 10. doi: 10.3389/fbioe.2022.958606 . hdl: 10871/130495 . ISSN   2296-4185.
  25. ↑ Brooks, W. H.; Guida, W. C.; Daniel, K. G. (2011). "The Significance of Chirality in Drug Design and Development". Current Topics in Medicinal Chemistry. 11 (7): 760–770. doi:10.2174/156802611795165098. PMC   5765859 . PMID   21291399.
  26. 1 2 Wu, Kai; Huang, Junhai; Shao, Lei (22 November 2022). "Imine Reductases: Multifunctional Biocatalysts with Varying Active Sites and Catalytic Mechanisms". ChemCatChem. 14 (22). doi:10.1002/cctc.202200921. ISSN   1867-3880. S2CID   252271457.
This page is based on this Wikipedia article
Text is available under the CC BY-SA 4.0 license; additional terms may apply.
Images, videos and audio are available under their respective licenses.