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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)

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)

Synthesis of α-Deuterated Primary Amines via Reductive Deuteration of Oximes Using D2O as a Deuterium Source
Selective introduction of the deuterium atom into the α-position of amines is important for the development of all types of novel deuterated drugs and agrochemicals due to the pervasive presence of amines. In this study, we report the first general single-electron-transfer reductive deuteration of both ketoximes and aldoximes using SmI2 as an electron donor and D2O as a deuterium source for the synthesis of α-deuterated primary amines with excellent levels of deuterium incorporations (>95% [D]). This protocol exhibits excellent chemoselectivity and tolerates a variety of functional groups. The potential application of this new method was showcased in the synthesis of deuterated drugs, such as rimantadine-d4, the tebufenpyrad analogue, derivatives of nabumetone and pregnenolone, and a series of building blocks for the rapid and general assembly of deuterated drugs and pesticides.
Ning, Lei,Li, Hengzhao,Lai, Zemin,Szostak, Michal,Chen, Xingyue,Dong, Yanhong,Jin, Shuhui,An, Jie
p. 2907 - 2916
(2021/02/27)

Method for preparing primary amine by catalyzing reductive amination of aldehyde ketone compounds
The invention discloses a method for preparing primary amine by catalyzing reductive amination of aldehyde ketone compounds. The method comprises the following steps: 1) mixing nickel nitrate hexahydrate, citric acid and an organic solvent, carrying out heating and stirring until a colloidal material is obtained, drying the colloidal material, roasting the colloidal material in a protective atmosphere, pickling, washing and drying a roasted product, and performing a partial oxidation reaction on a dried product in an oxygen-nitrogen mixed atmosphere to obtain a catalyst for a reductive amination reaction; and 2) mixing aldehyde or ketone compounds, a methanol solution of ammonia and the reductive amination reaction catalyst, introducing hydrogen, and carrying out a reductive amination reaction. The method has the advantages of high primary amine yield, high selectivity, wide aldehyde ketone substrate range, short reaction time, mild reaction conditions, low cost, greenness, economicalperformance and the like; the used reductive amination reaction catalyst can be recycled more than 10 times, and the catalytic activity of the catalyst is not obviously changed in gram-level reactions; and the method is suitable for large-scale application.
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Paragraph 0027-0030; 0080-0083

(2020/05/30)

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)

The Synthesis of Primary Amines through Reductive Amination Employing an Iron Catalyst
The reductive amination of ketones and aldehydes by ammonia is a highly attractive method for the synthesis of primary amines. The use of catalysts, especially reusable catalysts, based on earth-abundant metals is similarly appealing. Here, the iron-catalyzed synthesis of primary amines through reductive amination was realized. A broad scope and a very good tolerance of functional groups were observed. Ketones, including purely aliphatic ones, aryl–alkyl, dialkyl, and heterocyclic, as well as aldehydes could be converted smoothly into their corresponding primary amines. In addition, the amination of pharmaceuticals, bioactive compounds, and natural products was demonstrated. Many functional groups, such as hydroxy, methoxy, dioxol, sulfonyl, and boronate ester substituents, were tolerated. The catalyst is easy to handle, selective, and reusable and ammonia dissolved in water could be employed as the nitrogen source. The key is the use of a specific Fe complex for the catalyst synthesis and an N-doped SiC material as catalyst support.
B?umler, Christoph,Bauer, Christof,Kempe, Rhett
p. 3110 - 3114
(2020/06/01)

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)

Cobalt-Catalyzed Intermolecular Markovnikov Hydroamination of Nonactivated Olefins: N2-Selective Alkylation of Benzotriazole
Cobalt-catalyzed Markovnikov-selective hydroamination of nonactivated olefins was developed. Hydrogen atom transfer from a catalytically generated cobalt(III)-hydride complex to the olefins proceeded regioselectively, and the nucleophilic addition of benzotriazoles occurred selectively at their N2-positions. The synthetic utility of the obtained N2-alkylated benzotriazoles as stable amine protecting groups under various reaction conditions was demonstrated, and the products were also transformed into primary amines by zinc-mediated reduction.
Yahata, Kenzo,Kaneko, Yuki,Akai, Shuji
p. 598 - 603
(2020/02/04)

Cobalt-Catalyzed Markovnikov Selective Sequential Hydrogenation/Hydrohydrazidation of Aliphatic Terminal Alkynes
Here, we reported for the first time a mechanistically distinctive cobalt-catalyzed Markovnikov-type sequential semihydrogenation/hydrohydrazidation of aliphatic terminal alkynes in one pot. A cobalt hydride species was employed as two roles for both a unique metal-catalyzed Markovnikov-type insertion of the aliphatic terminal alkynes and then metal-catalyzed hydrogen atom transfer of alkenes. This operationally simple protocol exhibits excellent functional group tolerance and step economy. The hydrazone products could be easily transferred to various valuable amine derivatives.
Chen, Jieping,Shen, Xuzhong,Lu, Zhan
supporting information
p. 14455 - 14460
(2020/10/13)

Reductive amination of ketonic compounds catalyzed by Cp*Ir(III) complexes bearing a picolinamidato ligand
Cp*Ir complexes bearing a 2-picolinamide moiety serve as effective catalysts for the direct reductive amination of ketonic compounds to give primary amines under transfer hydrogenation conditions using ammonium formate as both the nitrogen and hydrogen source. The clean and operationally simple transformation proceeds with a substrate to catalyst molar ratio (S/C) of up to 20,000 at relatively low temperature and exhibits excellent chemoselectivity toward primary amines.
Tanaka, Kouichi,Miki, Takashi,Murata, Kunihiko,Yamaguchi, Ayumi,Kayaki, Yoshihito,Kuwata, Shigeki,Ikariya, Takao,Watanabe, Masahito
p. 10962 - 10977
(2019/09/03)

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)

Chemoselective Photoredox Synthesis of Unprotected Primary Amines Using Ammonia
Unprotected α-amino carbon radicals are produced as novel intermediates via a transformation that merges acid-promoted N-H imine generation and chemoselective photocatalytic single-electron reduction. Coupling ammonia and aldehydes/ketones allows the generation of primary amines under mild conditions without the need for protecting groups. The key intermediate can be efficiently transformed into primary (di)amines by a formal dimerization, reductive amination via hydrogen atom transfer, and arylation through radical-radical coupling.
Rong, Jiawei,Seeberger, Peter H.,Gilmore, Kerry
supporting information
p. 4081 - 4085
(2018/07/15)

Mild dynamic kinetic resolution of amines by coupled visible-light photoredox and enzyme catalysis
Herein, we described photoenzymatic dynamic kinetic resolution (DKR) of amines under mild conditions. The racemization of amines via a photoredox-mediated hydrogen atom transfer (HAT) protocol in conjunction with an enzyme catalyst to achieve the DKR of amines allows a variety of primary amines to be converted into a single enantiomer in high yield and with excellent enantioselectivity. Notably, this protocol can also be extended to 1,4-diamine derivatives with high levels of diastereo- and enantioselectivity.
Yang, Qiong,Zhao, Fengqian,Zhang, Na,Liu, Mingke,Hu, Huanhuan,Zhang, Jingjie,Zhou, Shaolin
supporting information
p. 14065 - 14068
(2019/01/03)

N-Alkylation of Aqueous Ammonia with Alcohols Leading to Primary Amines Catalyzed by Water-Soluble N-Heterocyclic Carbene Complexes of Iridium
A new catalytic system for the N-monoalkylation of aqueous ammonia with a variety of alcohols was developed. Water-soluble dicationic complexes of iridium bearing N-heterocyclic carbene and diammine ligands exhibited high catalytic activity for this type of reaction on the basis of hydrogen-transfer processes without generating harmful or wasteful byproducts. Various primary amines were efficiently synthesized by using safe, inexpensive, and easily handled aqueous ammonia as a nitrogen source. For example, the reaction of 1-(4-methylphenyl)ethanol with aqueous ammonia in the presence of a water-soluble N-heterocyclic carbene complex of iridium at 150 °C for 40 h gave 1-(4-methylphenyl)ethylamine in 83 % yield.
Fujita, Ken-Ichi,Furukawa, Shohichi,Morishima, Namino,Shimizu, Mineyuki,Yamaguchi, Ryohei
p. 1993 - 1997
(2018/03/13)

Development of a Unique Heterogeneous Palladium Catalyst for the Suzuki–Miyaura Reaction using (Hetero)aryl Chlorides and Chemoselective Hydrogenation
A unique heterogeneous palladium catalyst (7% Pd/WA30) supported on an anion exchange resin, which contains N,N-dimethylaminoalkyl functionalities on the polymer backbone, was developed. 7% Pd/WA30 could smoothly catalyze Suzuki–Miyaura reactions of even less reactive heteroaryl chlorides and heteroarylboronic acids to afford various (hetero)biaryls due to the electron-donating effect of the tert-amines on WA30 to Pd species. It was also applicable as a chemoselective hydrogenation catalyst, showing inactivity for the hydrogenolysis of tert-butyldimethylsilyl (TBS) ethers, alkyl benzyl ethers, and benzyl alcohols. The tert-amines on WA30 acted as moderate catalyst poisons for Pd, resulting in chemoselective hydrogenation. 7% Pd/WA30 was reused for at least five times without any loss of the hydrogenation catalytic activity. (Figure presented.).
Ichikawa, Tomohiro,Netsu, Moeko,Mizuno, Masahiro,Mizusaki, Tomoteru,Takagi, Yukio,Sawama, Yoshinari,Monguchi, Yasunari,Sajiki, Hironao
supporting information
p. 2269 - 2279
(2017/07/07)

Hybrid Organo- and Biocatalytic Process for the Asymmetric Transformation of Alcohols into Amines in Aqueous Medium
A hybrid organo- and biocatalytic system for the asymmetric conversion of racemic alcohols into amines was developed. Combining an organocatalyst, AZADO, an oxidant, NaOCl, and an enzyme, ω-transaminase, we implemented a one-pot oxidation-transamination sequential process in aqueous medium. The method showed broad substrate scope and was successfully applied to conventional secondary alcohols and sterically hindered β-substituted cycloalkanols, where a highly stereoselective dynamic asymmetric bioamination enabled us to set up both contiguous stereocenters with very high enantio- and diastereomeric ratio (>90% yield, >99% ee, and up to 49:1 dr).
Liardo, Elisa,Ríos-Lombardía, Nicolás,Morís, Francisco,Rebolledo, Francisca,González-Sabín, Javier
p. 4768 - 4774
(2017/07/24)

Catalytic C(sp3)?H Arylation of Free Primary Amines with an exo Directing Group Generated In Situ
Herein, we report the palladium-catalyzed direct arylation of unactivated aliphatic C?H bonds in free primary amines. This method takes advantage of an exo-imine-type directing group (DG) that can be generated and removed in situ. A range of unprotected aliphatic amines are suitable substrates, undergoing site-selective arylation at the γ-position. Methyl as well as cyclic and acyclic methylene groups can be activated. Furthermore, when aniline-derived substrates were used, preliminary success with δ-C?H arylation was achieved. The feasibility of using the DG component in a catalytic fashion was also demonstrated.
Xu, Yan,Young, Michael C.,Wang, Chengpeng,Magness, David M.,Dong, Guangbin
supporting information
p. 9084 - 9087
(2016/07/26)

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)

A Single Lipase-Catalysed One-Pot Protocol Combining Aminolysis Resolution and Aza-Michael Addition: An Easy and Efficient Way to Synthesise β-Amino Acid Esters
A novel one-pot protocol combining aza-Michael addition and aminolysis resolution was developed to obtain chiral β-amino acid esters with lipase B from Candida antarctica (CAL-B) as the only catalyst. This method is conducted under mild reaction conditions and is very easy to handle. After a series of detailed optimization studies, ten racemic aromatic or aliphatic amines were subjected to this one-pot procedure, and twelve chiral β-amino acid esters and ten chiral amides were successfully synthesised with excellent ee values in theoretical yields. Scaled-up procedures also worked without apparent reduction in reaction rate or enantioselectivity, which makes this method suitable for large-scale production of chiral β-amino acid esters. A one-pot protocol for simultaneous synthesis of chiral β-amino acid esters and amides was developed by combining single lipase B from Candida antarctica (CAL-B) catalysed aza-Michael addition and aminolysis resolution. This method requires mild reaction conditions and is very easy to handle. Chiral β-amino acid esters and chiral amides were obtained with excellent ee values and in theoretical yields.
Xu, Fan,Wu, Qiongsi,Chen, Xiaoyang,Lin, Xianfu,Wu, Qi
supporting information
p. 5393 - 5401
(2015/08/24)

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)

Artificial multi-enzyme networks for the asymmetric amination of sec-alcohols
Various artificial network designs that involve biocatalysts were tested for the asymmetric amination of sec-alcohols to the corresponding α-chiral primary amines. The artificial systems tested involved three to five redox enzymes and were exemplary of a range of different sec-alcohol substrates. Alcohols were oxidised to the corresponding ketone by an alcohol dehydrogenase. The ketones were subsequently aminated by employing a ω-transaminase. Of special interest were redox-neutral designs in which the hydride abstracted in the oxidation step was reused in the amination step of the cascade. Under optimised conditions up to 91 % conversion of an alcohol to the amine was achieved. Trickle-down effect: The asymmetric amination of sec-alcohols to the corresponding α-chiral primary amines was performed with a biocatalytic cascade whereby the various steps were interconnected through the cofactors/cosubstrates. In a redox-neutral cascade and under optimised conditions, up to 91 % conversion of an alcohol to the amine was achieved. Copyright
Tauber, Katharina,Fuchs, Michael,Sattler, Johann H.,Pitzer, Julia,Pressnitz, Desiree,Koszelewski, Dominik,Faber, Kurt,Pfeffer, Jan,Haas, Thomas,Kroutil, Wolfgang
p. 4030 - 4035
(2013/04/10)

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 0079

(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)

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
supporting information; experimental part
p. 2085 - 2092
(2011/10/19)

Reductive amination of ketones: Novel one-step transfer hydrogenations in batch and continuous-flow mode
Various ketones were efficiently transformed into the corresponding amines using ammonium formate in the presence of Zn dust or 10% Pd/C. The low-cost Zn dust method proved to be effective in amine formation from carbonyl groups at the benzylic side-chain position of aromatic systems, whereas 10% Pd/C was an efficient catalyst in the reductive aminations of carbonyl groups non-conjugated with any π-system. The 10% Pd/C-catalyzed reductions were performed more effectively in a continuous-flow X-Cube reactor than in the batch system.
Falus, Péter,Boros, Zoltán,Hornyánszky, Gábor,Nagy, József,Darvas, Ferenc,ürge, László,Poppe, László
supporting information; experimental part
p. 1310 - 1312
(2011/03/22)

Aerobic oxidation of amines catalyzed by polymer-incarcerated au nanoclusters: Effect of cluster size and cooperative functional groups in the polymer
Aerobic oxidation reaction of amines to imines catalyzed by polymer-incarcerated Au nanoclusters (PI-Au) was developed. The effect of cluster size for this oxidation reaction was carefully examined using the same polymer support. We have succeeded in preparation of various PI-Au catalysts containing different size clusters by modification of standard preparation methods. The size of clusters and their distribution were analyzed by electron microscopy. Interestingly, catalysts containing relatively larger clusters (>5 nm) showed higher activity in aerobic oxidation of amines than catalysts containing smaller clusters (13 nm) that showed much better activity for aerobic oxidation of alcohols. In addition, novel Au nanocluster catalysts immobilized on newly prepared polymer with tertiary amine groups were developed and they showed excellent activity for aerobic oxidation of amines to imines. The relation between cluster size and catalytic activity and role of tertiary amine in polymer were discussed. These catalysts could be applied to aerobic oxidative deprotection of p-methoxybenzyl groups.
Miyamura, Hiroyuki,Morita, Masataka,Inasaki, Takeshi,Kobayashi, Shu
p. 588 - 599
(2011/08/09)

Testing of microorganisms for ω-transaminase activity
Various bacterial cells were tested to identify ω-transaminase activity. For this purpose, the kinetic resolution of a rac-amine was chosen as an assay reaction transforming, in the ideal case, one enantiomer into the corresponding ketone and leaving the other enantiomer untouched. Sodium pyruvate was employed as an amino acceptor. To test also for the amination of the prochiral ketone various amino donors were investigated. Alanine proved to be the most suitable amino donor especially when coupled with a pyruvate decarboxylase to shift the reaction equilibrium; however, much lower conversions were achieved compared to the kinetic resolution. Janibacter terrae DSM 13953 was identified as the most suitable microorganism to possess ω-transaminase activity.
Clay, Dorina,Koszelewski, Dominik,Grischek, Barbara,Gross, Johannes,Lavandera, Ivan,Kroutil, Wolfgang
scheme or table
p. 2005 - 2009
(2010/10/20)

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)

En route to (S)-selective chemoenzymatic dynamic kinetic resolution of aliphatic amines. One-pot KR/racemization/KR sequence leading to (S)-amides
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El Blidi, Lahssen,Nechab, Malek,Vanthuyne, Nicolas,Gastaldi, Stephane,Bertrand, Michele P.,Gil, Gerard
supporting information; experimental part
p. 2901 - 2903
(2009/09/05)

Heterogeneous raney nickel and cobalt catalysts for racemization and dynamic kinetic resolution of amines
Raney metals were studied as heterogeneous catalysts for racemization and dynamic kinetic resolution (DKR) of chiral amines, as an alternative to metals like palladium or ruthenium. Both Raney nickel and cobalt were able to selectively racemize various chiral amines with high selectivity. In the racemization of benzylic primary amines, the minor formation of side products, e.g., secondary amines, can be suppressed by varying the hydrogen pressure. In the racemization of aliphatic amines over Raney catalysts, the selectivity is very high, with the enantiomeric amine as the sole product. DKR of racemic aliphatic amines can be performed with immobilized Candida antarctica lipase B and Raney nickel in one pot; for 2-hexylamine, a yield of 95% of the acetylated amide was achieved, with 97% ee. Attention is devoted to the compatibility of the enzyme and the metal catalyst during the DKR. For benzylic primary amines, a two-pot process is proposed in which the liquid is alternatingly shuttled between two vessels containing the solid racemization catalyst and the biocatalyst. After 4 such cycles, the amide of (R)-1-phenylethylamine was obtained with 94% yield and more than 90% ee.
Parvulescu, Andrei N.,Jacobs, Pierre A.,De Vos, Dirk E.
scheme or table
p. 113 - 121
(2009/04/16)

Estrogen receptor ligands. Part 16: 2-Aryl indoles as highly subtype selective ligands for ERα
A novel class of indole ligands for estrogen receptor α have been discovered which exhibit potent affinity and high selectivity. Substitution of the bazedoxifene skeleton to the linker present in the HTS lead 1a provided 22b which was found to be 130-fold α-selective and acted as an antagonist of estradiol activity in uterine tissue and MCF-7 cancer cells.
Dykstra, Kevin D.,Guo, Liangqin,Birzin, Elizabeth T.,Chan, Wanda,Yang, Yi Tien,Hayes, Edward C.,DaSilva, Carolyn A.,Pai, Lee-Yuh,Mosley, Ralph T.,Kraker, Bryan,Fitzgerald, Paula M.D.,DiNinno, Frank,Rohrer, Susan P.,Schaeffer, James M.,Hammond, Milton L.
p. 2322 - 2328
(2007/10/03)

Determination of labetalol hydrochloride in drug formulations by spectrophotometry
A validated, selective and sensitive spectrophotometric method has been developed for the determination of labetalol hydrochloride in commercial dosage forms. The method is based on the coupling reaction of positive diazonium ion of 4-aminobenzenesulfonic acid with phenolate ion of labetalol to form a colored azo compound which absorbs maximally at 395 nm. Under the optimized experimental conditions, the color is stable up to 2 h and Beer's law is obeyed in the concentration range of 0.8-17.6 μg mL-1 with a linear regression equation of A = 4.84 × 10-4 + 7.864 × 10-2 C and coefficient of correlation, r = 0.9999. The molar absorptivity and Sandell's sensitivity are found to be 2.874 × 104 L mol-1 cm-1 and 0.013 μg cm-2 per 0.001-absorbance unit, respectively. The limits of detection and quantitation of the proposed method are 0.08 and 0.23 μg mL-1, respectively. The intra-day and inter-day precision variation and accuracy of the proposed method is acceptable with low values of standard analytical error. The recovery results obtained by the proposed method in drug formulations are acceptable with mean percent recovery ± RSD of 99.97 ± 0.52 - 100.03 ± 0.63%. The results of the proposed method compared with those of Bilal's spectrophotometric method indicated excellent agreement with acceptable true bias of all samples within ± 2.0%.
Rahman, Nafisur,Rahman, Habibur,Azmi, Syed Najmul Hejaz
p. 185 - 196
(2008/02/09)

Laccase-mediated deprotection of para-methoxyphenyl (PMP)-protected amines
A novel enzymatic procedure for the oxidative deprotection of p-methoxyphenyl (PMP)protected amines is described. By using laceases (E.C. 1.10.3.2) under mildly acidic conditions, a variety of PMP-protected amines were successfully deprotected. The rate of deprotection was solvent-and pH-dependent, and the reaction scope could be increased by using so-called mediators
Verkade, Jorge M. M.,Van Hemert, Lieke J. C.,Quaedflieg, Peter J. L. M.,Schoemaker, Hans E.,Schuermann, Martin,Van Delft, Floris L.,Rutjes, Floris P. J. T.
p. 1332 - 1336
(2008/03/28)

Hydrazines and azides via the metal-catalyzed hydrohydrazination and hydroazidation of olefins
The discovery, study, and implementation of the Co- and Mn-catalyzed hydrohydrazination and hydroazidation reactions of olefins are reported. These reactions are equivalent to direct hydroaminations of C-C double bonds with protected hydrazines or hydrazoic acid but are based on a different concept in which the H and the N atoms come from two different reagents, a silane and an oxidizing nitrogen source (azodicarboxylate or sulfonyl azide). The hydrohydrazination reaction using di-tert-butyl azodicarboxylate is characterized by its ease of use, large functional group tolerance, and broad scope, including mono-, di-, tri-, and tetrasubstituted olefins. Key to the development of the hydroazidation reaction was the use of sulfonyl azides as nitrogen sources and the activating effect of tert-butyl hydroperoxide. The reaction was found to be efficient for the functionalization of mono-, di-, and trisubstituted olefins, and only a few functional groups are not tolerated. The alkyl azides obtained are versatile intermediates and can be transformed to the free amines or triazoles without isolation of the azides. Preliminary mechanistic investigations suggest a rate-limiting hydrocobaltation of the alkene, followed by an amination reaction. Radical intermediates cannot be ruled out and may be involved.
Waser, Jerome,Gaspar, Boris,Nambu, Hisanori,Carreira, Erick M.
p. 11693 - 11712
(2007/10/03)

Efficient N-p-methoxyphenyl amine deprotection through anodic oxidation
A new method of deprotection of N-p-methoxyphenylamines using anodic oxidation in acidic medium is presented. The process furnishes a high yield of amine and is compatible with several oxidable functional groups.
De Marin, Sandra Lamo,Martens, Thierry,Mioskowski, Charles,Royer, Jacques
p. 10592 - 10595
(2007/10/03)

Cobalt-catalyzed hydroazidation of olefins: Convenient access to alkyl azides
Conversion of olefins to azides was achieved with high Markovnikov selectivity for a broad range of alkenes using 6 mol % Co(BF4)·6H2O and ligand 1, with 3 equiv of TsN3 as nitrogen source and simple silanes (PhSiH3, TMDSO). Copyright
Waser, Jerome,Nambu, Hisanori,Carreira, Erick M.
p. 8294 - 8295
(2007/10/03)

Chemoselective reductive alkylation of ammonia with carbonyl compounds: Synthesis of primary and symmetrical secondary amines
An efficient, general procedure for highly chemoselective reductive mono-alkylation of ammonia with ketones is reported. Treatment of ketones with ammonia in ethanol and titanium(IV) isopropoxide, followed by in situ sodium borohydride reduction, and a straightforward workup afforded primary amines in good to excellent yields. Reductive alkylation of ammonia with aldehydes, on the other hand, afforded the corresponding symmetrical secondary amines selectively.
Miriyala, Bruhaspathy,Bhattacharyya, Sukanta,Williamson, John S.
p. 1463 - 1471
(2007/10/03)

Synthesis of primary amines and N-methylamines by the electrophilic amination of Grignard reagents with 2-imidazolidinone O-sulfonyloxime
2-Imidazolidinone O-sulfonyloxime reacts with various aryl and alkyl Grignard reagents as an electrophilic amination reagent, giving N-alkylated imines. The resulting imines are transformed to primary amines and N-methyl secondary amines by hydrolysis with CsOH and LiAlH4 reduction, respectively.
Kitamura, Mitsuru,Chiba, Shunsuke,Narasaka, Koichi
p. 1063 - 1070
(2007/10/03)

New Simple Polymeric Supports with Hydrazone Linkers for Solid-Phase Synthesis of Ketones and Primary Amines
The preparation of new solid supports with hydrazine anchoring groups and their application to solid-phase synthesis of ketones and primary amines are described. The supports were used for immobilization of ketones, 4-tert-butylcyclohexanone, pentan-3-one, acetone, N-methylpiperidone, N-benzylpiperidone, and tropinone in the form of their hydrazones. The polymer-supported hydrazones were subjected to deprotonation/alkylation procedure (LDA/RX) once or twice. The resulting alkylated products were cleaved off the solid support on treatment with trifluoroacetic acid in tetrahydrofuran providing α-alkylated or α,α′-bisalkylated ketones or were subjected to reductive cleavage with borane in tetrahydrofuran to give β-alkylated or β,β′-bisalkylated primary amines.
Lazny, Ryszard,Nodzewska, Aneta,Wolosewicz, Karol
p. 2858 - 2864
(2007/10/03)

2-aminobenzoxazole derivatives and combinatorial libraries thereof
The present invention relates to novel 2-aminobenzoxazole derivative compounds of the following formula: wherein R1 to R4 and Z have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminobenzoxazole derivative compounds.
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(2008/06/13)

2-aminopyridine derivatives and combinatorial libraries thereof
The present invention relates to novel 2-aminopyridine derivative compounds of the following formula: wherein R1to R5have the meanings provided herein. The invention further relates to combinatorial libraries containing two or more such compounds, as well as methods of preparing 2-aminopyridine derivative compounds.
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(2008/06/13)

CAL-B-catalyzed resolution of some pharmacologically interesting β-substituted isopropylamines
Some pharmacologically active amines such as amphetamine, the isomeric o-, m- and p-methoxyamphetamines, 4-phenylbutan-2-amine and mexiletine, as well as their corresponding acetamides, have been prepared in high yields and with very high enantiomeric excesses. The method consists of the Candida antarctica lipase B (CAL-B)-mediated enantioselective acetylation of racemic amines using ethyl acetate as solvent and acyl donor. The enzyme follows Kazlauskas' rule with all amines, (R)-amides being obtained as the major enantiomer in all cases. From the conversion values measured for both enantiomers, it can be deduced that the size of the substituents attached to the stereocenter is responsible for the enantioselectivity and rate of some of these reactions.
Gonzalez-Sabin, Javier,Gotor, Vicente,Rebolledo, Francisca
p. 1315 - 1320
(2007/10/03)

Stereoselectivity of cyclisations via N-acyliminium ions to form pyrido[2′,3′:3,4]pyrrolo[2,1-a]isoindole, -isoquinoline and -benz[c]azepine ring systems
Pyrido[2′,3′:3,4]pyrrolo[2,1-a]isoindole, -isoquinoline and -benz[c]azepine derivatives are obtained by heating in polyphosphoric acid (PPA) appropriate hydroxy lactam precursors derived from pyridine-2,3-dicarboximides. The stereoselectivity of ring closure is rationalised by considering the development of A(1,3) strain in the cyclisation step from N-acyliminium ion intermediates.
Bahajaj,Vernon,Wilson
p. 1446 - 1451
(2007/10/03)

Studies on the photostability and in vitro phototoxicity of Labetalol
The purpose of this study was to obtain information on the photochemical and phototoxic properties of Labetalol, a beta-blocker drug. Preliminary information on the drug photoreactivity was achieved using a flow system with a photochemical reactor on-line with a diode array detection system. Photophysical and photochemical investigations on the drug were performed in aqueous solutions at different pH values using spectrophotometric and fluorimetric methods; the photodegradation quantum yield was found to be 2.7×10-3 at pH 5.8 and 1.5×10-2 at pH 11.5. Forced photodegradation of labetalol solutions under exposure to UVA-UVB radiations (xenon arc lamp) was monitored by reversed-phase liquid chromatography. The main photodegradation products were isolated and characterized by NMR and mass spectrometry; labetalol was found to give 3-amino-1-phenylbutane and salicylamide-4-carboxaldehyde as the main photoproducts. Preliminary phototoxic testings on human keratinocyte cultures were performed evaluating the viability of the cells by the neutral-red uptake assay; mutagenic and photomutagenicity tests were also carried out based on Salmonella typhimurium strains. As a result, labetalol was found to be photolabile,mainly in alkaline medium, but evidences of significant phototoxic and photomutagenic effects by the drug were not observed. Copyright
Andrisano, Vincenza,Ballardini, Roberto,Hrelia, Patrizia,Cameli, Norma,Tosti, Antonella,Gotti, Roberto,Cavrini, Vanni
p. 495 - 504
(2007/10/03)

Preparation of secondary amines by reductive animation with metallic magnesium
A novel and efficient method for the preparation of secondary amines by reductive animation of carbonyl compounds with primary amines has been developed. The reduction, effected with metallic magnesium in methanol, utilizing triethylamine-acetic acid as a buffer, gave pure secondary amines, mostly in good yields (65-80%). No formation of tertiary amines or alcohols was observed. Use of ammonium acetate as an amino component gave primary amines in modest yields (ca. 50%), together with variable amounts of secondary amines. Enamines failed to undergo reduction. The method is inexpensive, relatively rapid, operationally simple and suitable for large-scale preparations. In addition, a simple method for separation of primary amines from secondary ones has been developed.
Micovic, Ivan V.,Ivanovic,Roglic, Goran M.,Kiricojevic, Vesna D.,Popovic, Jelena B.
p. 265 - 269
(2007/10/03)

A convenient two-pot conversion of aldehydes to sec-alkyl primary amines: Reactions of α-(benzotriazol-1-yl)alkyl-iminophosphoranes with organocerium (III) or Grignard reagents
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Katritzky,Mazurkiewicz,Stevens,Gordeev,Steel
p. 2955 - 2972
(2007/10/02)

Hydrogenolysis of 3-methyl-4-phenylmethyl-5(2H)-isoxazolone derivatives: A reinvestigation
Hydrogenolysis of 3-methyl-4-phenylmethyl-5(2H)-isoxazolone (2a) and its derivatives 2b-e, 5a-e, 6a-e and 9a,b have been carried out over Pd/C and Raney-nickel.The products have been isolated and characterized.The intermediate products of hydrogenolysis of 2b-e have been trapped and simultaneous cleavage of N - O and C - C bonds in 9a,b has been suggested to explain the formation of the hydrogenolysis products 10a,b and 3a,b.
Batra, Sanjay,Seth, M,Bhaduri, A P
p. 60 - 62
(2007/10/02)

Derivatives related to betaxolol with α- and β-adrenergic activities
The paper describes the synthesis and the pharmacological evaluation of some derivatives of betaxolol, all with an N-aralkylamine instead of the tertiobutylamine. These compounds have been tested for β1-adrenergic receptor antagonism on guinea pig atria, β2-adrenergic receptor antagonism on guinea pig trachea and α-adrenergic blocking activity on rat aorta. Compound U12 with a marked α-blocking activity and compound R8 with a β1/α ratio = 1 were selected for a haemodynamic study in the dog. The decrease in cardiac work and the diminution of total peripheral resistance exhibited by U12 are consistent with a dual α/β-blocking agent. Finally, structure-activity relationships are discussed.
Leclerc,Decker,Schwartz
p. 1357 - 1367
(2007/10/02)

Reduction of Oximes with Sodium Borohydride in the Presence of Transition Metal Compounds
The reduction of oximes with sodium borohydride in the presence of NiCl2 * 6 H2O and MoO3 was investigated.The combination of NaBH4 with NiCl2 * 6 H2O converted the unsaturated oximes through exhaustive reduction into saturated amines (Table 1).The C = C double bond remains preserved if the reduction is carried out in the presence of MoO3 (Table 2).The stereochemistry of the reduction in the presence of NiCl2 * 6 H2O is distinctivly different from that of MoO3.
Ipaktschi, Junes
p. 856 - 858
(2007/10/02)