- Morphology-Tuned Activity of Ru/Nb2O5 Catalysts for Ketone Reductive Amination
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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
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- Reductive amination of bio-based 2-hydroxytetrahydropyran to 5-Amino-1-pentanol over nano-Ni-Al2O3catalysts
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The synthesis of useful amines from bio-based carbonyl compounds is highly desired owing to their mild reaction conditions and green sustainability. The reductive amination of bio-furfural-derived 2-hydroxytetrahydropyran (2-HTHP) to high-value-added 5-Amino-1-pentanol (5-AP) was carried out over efficient Ni-Al2O3catalysts prepared by a co-precipitation method. Among the Ni-Al2O3catalysts with different Ni loadings (0-100 wt%) tested, the 50Ni-Al2O3catalyst exhibited the highest5-APyield of 91.3% under mild conditions of 60 °C and 2 MPa H2. This catalyst also presented good stability during a 150 h time-on-stream without appreciable deactivation. Characterization results showed that the 50Ni-Al2O3catalyst exhibited small Ni0nanoparticles (5.5 nm), a high reduction degree (up to 95%), and a large amount of strong Lewis acid sites. The cooperative catalysis of the strong Lewis acid sites and highly dispersed metallic Ni sites is suggested to play an important role in achieving high efficiency in2-HTHPreductive amination.
- Zhang, Jia,Yang, Jian,Tian, Junying,Liu, Hailong,Li, Xuemei,Fang, Weiguo,Hu, Xun,Xia, Chungu,Chen, Jing,Huang, Zhiwei
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- Modulating: Trans -imination and hydrogenation towards the highly selective production of primary diamines from dialdehydes
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Bio-based primary diamines are important building blocks for sustainable bio-polymers, but their synthesis remains challenging due to the high susceptibility to polymerization. Herein, we have developed a new strategy to suppress the polymerization by employing a more nucleophilic alkylamine to scavenge the dialdehyde and a Co/ZrO2 catalyst to regulate the trans-imination and hydrogenation activity. With this strategy, 2,5-bis(aminomethyl)furan (BAMF), a promising monomer for the production of new polyamides and polyureas, is successfully synthesized via the reductive amination of biomass-derived 2,5-diformylfuran (DFF) under a H2 and NH3 atmosphere with an unprecedentedly high selectivity up to 95%. This strategy is applicable to the reductive amination of other biomass-derived dialdehydes, thus paving a new way to bio-based diamine monomers. This journal is
- Hao, Rui,Li, Lin,Liu, Fei,Qi, Haifeng,Su, Yang,Wang, Aiqin,Yang, Jingyi,Zhang, Leilei,Zhang, Tao
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- Simple and efficient Fmoc removal in ionic liquid
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A mild method for an efficient removal of the fluorenylmethoxycarbonyl (Fmoc) group in ionic liquid was developed. The combination of a weak base such as triethylamine and [Bmim][BF4] makes the entire system more efficient for the cleavage at room temperature of various amines and amino acid methyl esters in short reaction times. The procedure works well even in the case of N-Fmoc amino acids bearing acid-sensitive protecting groups and of N-alkylated amino acid methyl esters. The solvent-free condition provides a complementary method for Fmoc deprotection in solution phase peptide synthesis and modern organic synthesis.
- Di Gioia,Costanzo,De Nino,Maiuolo,Nardi,Olivito,Procopio
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- Aminoborohydrides. 8. A facile reduction of aliphatic and benzylic azides to the corresponding amines in high yield and purity using lithium N,N-dimethylaminoborohydride
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Lithium N,N-dimethylaminoborohydride (LiMe2NHB3) reduced both 3α-azidocholest-5-ene and 3β-azidocholest-5-ene in air to give the corresponding 3α-aminocholest-5-ene and 3β-aminocholest-5-ene in 98% isolated yields. Aliphatic and benzylic azides were also reduced with LiMe2NBH3 to give the corresponding amines in isolated yields ranging from 85 to 98%. The reductions were complete in 1-3 hours and required only a simple acid-base extraction to isolate the desired amines.
- Alvarez,Fisher,Singaram
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- Organic reactions in a solid matrix-VII sodium on alumina: A convenient reagent for reduction of ketones, esters and oximes
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Sodium dispersed on alumina is described and evaluated as a convenient off-the-shelf reagent (in a wax-coated form) for reduction of ketones, esters and oximes. While isopropanol is the preferred proton donor for the reduction of ketones and oximes, t-butanol is the alcohol of choice for the reduction of esters.
- Singh, Satendra,Dev, Sukh
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- Production of Primary Amines by Reductive Amination of Biomass-Derived Aldehydes/Ketones
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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
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- Heterogeneous Catalytic Reductive Amination of Carbonyl Compounds with Ni-Al Alloy in Water as Solvent and Hydrogen Source
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The heterogeneous catalytic reductive amination of carbonyl compounds has been achieved by reactions of ammonium hydroxide and various amines with ketones and aldehydes. The process is based on the application of Raney type Ni-Al alloy in an aqueous medium. The reaction of the carbonyl compounds with the amine provided the corresponding Schiff bases that immediately underwent a reduction to provide primary and secondary amines as products. The controlled reaction of the Al content of the alloy with the solvent water generates hydrogen, and the in situ formed Raney Ni serves as a hydrogenation catalyst. The method is a simple and efficient way of preparing a broad variety of primary and secondary amines.
- Sch?fer, Christian,Ni?anci, Bilal,Bere, Matthew P.,Da?tan, Arif,T?r?k, Béla
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- The evolution of an amine dehydrogenase biocatalyst for the asymmetric production of chiral amines
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The reductive amination of ketones to produce chiral amines is an important transformation in the production of pharmaceutical intermediates. Therefore, industrially applicable enzymatic methods that enable the selective synthesis of chiral amines could be very useful. Using a phenylalanine dehydrogenase scaffold devoid of amine dehydrogenase activity, a robust amine dehydrogenase has been evolved with a single two-site library allowing for the direct production of (R)-1-(4-fluorophenyl)-propyl-2-amine from para- fluorophenylacetone with a kcat value of 6.85 s-1 and a KM value of 7.75 mM for the ketone substrate. This is the first example of a highly active amine dehydrogenase capable of accepting aliphatic and benzylic ketone substrates. The stereoselectivity of the evolved amine dehydrogenase was very high (>99.8% ee) showing that high selectivity of the wild-type phenylalanine dehydrogenase was conserved in the evolution process. When paired with glucose/glucose dehydrogenase, NADH cofactor can be effficiently regenerated and the reaction driven to over 93% conversion. The broad specificity, high selectivity, and near complete conversion render this amine dehydrogenase an attractive target for further evolution toward pharmaceutical compounds and subsequent application. Copyright
- Abrahamson, Michael J.,Wong, John W.,Bommarius, Andreas S.
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- Ambient-Temperature Synthesis of Primary Amines via Reductive Amination of Carbonyl Compounds
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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
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- Continuous flow hydrogenation of nitroarenes, azides and alkenes using maghemite-Pd nanocomposites
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Maghemite-supported ultra-fine Pd (1-3 nm) nanoparticles, prepared by a simple co-precipitation method, find application in the catalytic continuous flow hydrogenation of nitroarenes, azides, and alkenes wherein they play an important role in the reduction of various functional groups on the surface of maghemite with catalyst loading (~6 wt% Pd). The salient features of the protocol include expeditious formation of reduced products in high yields under near ambient conditions with recycling of the catalyst (up to 12 cycles) without any decrease in selectivity and yield.
- Rathi, Anuj K.,Gawande, Manoj B.,Ranc, Vaclav,Pechousek, Jiri,Petr, Martin,Cepe, Klara,Varma, Rajender S.,Zboril, Radek
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- Selective monoalkylation of ammonia: A high throughput synthesis of primary amines
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Primary amines are obtained in good to excellent yields by highly selective monoalkylation of ammonia with alkyl and aryl ketones using titanium(IV) isopropoxide and sodium borohydride.
- Bhattacharyya, Sukanta,Neidigh, Kurt A.,Avery, Mitchell A.,Williamson, John S.
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- Chemoselective reductive alkylation of ammonia with carbonyl compounds: Synthesis of primary and symmetrical secondary amines
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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.
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- Development and Application of Efficient Ag-based Hydrogenation Catalysts Prepared from Rice Husk Waste
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The development of strategies for the sustainable management and valorization of agricultural waste is of outmost importance. With this in mind, we report the use of rice husk (RH) as feedstock for the preparation of heterogeneous catalysts for hydrogenation reactions. The catalysts were prepared by impregnating the milled RH with a silver nitrate solution followed by carbothermal reduction. The composition and morphology of the prepared catalysts were fully assessed by IR, AAS, ICP-MS, XPS, XRD and STEM techniques. This novel bio-genic silver-based catalysts showed excellent activity and remarkable selectivity in the hydrogenation of nitro groups in both aromatic and aliphatic substrates, even in the presence of reactive functionalities like halogens, carbonyls, borate esters or nitriles. Recycling experiments showed that the catalysts can be easily recovered and reused multiple times without significant drop in performance and without requiring re-activation.
- Unglaube, Felix,Kreyenschulte, Carsten Robert,Mejía, Esteban
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p. 2583 - 2591
(2021/04/09)
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- A mild and selective Cu(II) salts-catalyzed reduction of nitro, azo, azoxy, N-aryl hydroxylamine, nitroso, acid halide, ester, and azide compounds using hydrogen surrogacy of sodium borohydride
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The first mild, in situ, single-pot, high-yielding well-screened copper (II) salt-based catalyst system utilizing the hydrogen surrogacy of sodium borohydride for selective hydrogenation of a broad range of nitro substrates into the corresponding amine under habitancy of water or methanol like green solvents have been described. Moreover, this catalytic system can also activate various functional groups for hydride reduction within prompted time, with low catalyst-loading, without any requirement of high pressure or molecular hydrogen supply. Notably, this system explores a great potential to substitute expensive traditional hydrogenation methodologies and thus offers a greener and simple hydrogenative strategy in the field of organic synthesis.
- Kalola, Anirudhdha G.,Prasad, Pratibha,Mokariya, Jaydeep A.,Patel, Manish P.
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supporting information
p. 3565 - 3589
(2021/10/12)
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- Biochemical and Structural Characterization of an (R)-Selective Transaminase in the Asymmetric Synthesis of Chiral Hydroxy Amines
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An (R)-selective transaminase RbTA with excellent stereoselectivity (>99% ee) in the asymmetric amination of hydroxy ketones was identified. Biochemical characterization showed that RbTA exhibited the highest activity toward 4-hydroxy-2-butanone among reported enzymes, and that it has broad substrate specificity, including for aliphatic, aromatic, and alicyclic ketones. Crystallization of RbTA were performed, as were molecular docking and mutagenesis studies. Residue Tyr125 plays a key role in substrate recognition by forming a hydrogen bond with hydroxy ketone. The applicability of the enzyme was determined in preparative-scale synthesis of (R)-3-amino-1-butanol, demonstrating the potential of RbTA as a green biocatalyst for production of value-added chiral hydroxy amines. This study provides an efficient tool for enzymatic synthesis of chiral hydroxy amines, as well as structural insight into substrate recognition by transaminases in the asymmetric amination of hydroxy ketones. (Figure presented.).
- Li, Fulong,Liang, Youxiang,Wei, Yuwen,Zheng, Yukun,Du, Yan,Yu, Huimin
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p. 4582 - 4589
(2021/08/07)
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- Self-regulated catalysis for the selective synthesis of primary amines from carbonyl compounds
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Most current processes for the general synthesis of primary amines by reductive amination are performed with enormously excessive amounts of hazardous ammonia. It remains unclear how catalysts should be designed to regulate amination reaction dynamics at a low ammonia-to-substrate ratio for the quantitative synthesis of primary amines from the corresponding carbonyl compounds. Herein we show a facile control of the reaction selectivity in the layered boron nitride supported ruthenium catalyzed reductive amination reaction. Specifically, locating ruthenium to the edge surface of layered boron nitride leads to an increased hydrogenation activity owing to the enhanced interfacial electronic effects between ruthenium and the edge surface of boron nitride. This enables self-accelerated reductive amination reactions which quantitatively synthesize structurally diverse primary amines by reductive amination of carbonyl compounds with twofold ammonia. This journal is
- Fan, Xiaomeng,Gao, Jin,Gao, Mingxia,Jia, Xiuquan,Ma, Jiping,Xu, Jie
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supporting information
p. 7115 - 7121
(2021/09/28)
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- Synthesis of Chiral Amines via a Bi-Enzymatic Cascade Using an Ene-Reductase and Amine Dehydrogenase
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Access to chiral amines with more than one stereocentre remains challenging, although an increasing number of methods are emerging. Here we developed a proof-of-concept bi-enzymatic cascade, consisting of an ene reductase and amine dehydrogenase (AmDH), to afford chiral diastereomerically enriched amines in one pot. The asymmetric reduction of unsaturated ketones and aldehydes by ene reductases from the Old Yellow Enzyme family (OYE) was adapted to reaction conditions for the reductive amination by amine dehydrogenases. By studying the substrate profiles of both reported biocatalysts, thirteen unsaturated carbonyl substrates were assayed against the best duo OYE/AmDH. Low (5 %) to high (97 %) conversion rates were obtained with enantiomeric and diastereomeric excess of up to 99 %. We expect our established bi-enzymatic cascade to allow access to chiral amines with both high enantiomeric and diastereomeric excess from varying alkene substrates depending on the combination of enzymes.
- Fossey-Jouenne, Aurélie,Jongkind, Ewald P. J.,Mayol, Ombeline,Paul, Caroline E.,Vergne-Vaxelaire, Carine,Zaparucha, Anne
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- Facile synthesis of controllable graphene-co-shelled reusable Ni/NiO nanoparticles and their application in the synthesis of amines under mild conditions
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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
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supporting information
p. 7387 - 7397
(2020/11/19)
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- Rapid synthesis method of biomass-based amide
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The invention discloses a rapid synthesis method of biomass-based amide, which comprises the steps: formamide is used as an amine source, formic acid is used as a hydrogen source, biomass aldehyde andketone is used as a raw material, the direct addition of formamide and aldehyde and ketone components and the reduction of formic acid is promoted to prepare the corresponding formamide derivative byrapidly heating under microwave-assisted heating and in the absence of a solvent and a catalyst; the formamide derivative is selectively converted to the corresponding primary amide by alcoholysis under the action of a base. The microwave assisted heating reaction system of the invention has higher catalytic efficiency than the corresponding oil bath system, greatly shortens the reaction time, remarkably improves the selectivity. The conversion rate of the biomass aldehyde or ketone compound is at least 99%, and the yield of the formamide derivative can reach 85 to 99%; the formamide can be synthesized by alcoholysis to obtain a primary amide with a yield of 92 to 99%.
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- Trinuclear {Co2+-M3+-Co2+} complexes catalyze reduction of nitro compounds
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This work presents synthesis and characterization of trinuclear {Co2+-Co3+-Co2+} and {Co2+-Fe3+-Co2+} complexes with accessible peripheral Co(ii) ions. Both trinuclear complexes function as efficient reusable heterogeneous catalysts for the selective reduction of assorted nitro compounds to the corresponding amines. The mechanistic investigations suggest the involvement of a Co(ii)-Co(i) cycle in the catalysis.
- Srivastava, Sumit,Dagur, Manvender S.,Ali, Afsar,Gupta, Rajeev
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p. 17453 - 17461
(2015/10/19)
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- Method for manufacturing ammonia-N
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PROBLEM TO BE SOLVED: To provide a method for producing an N-alkyl hydroxylamine, which produces a pure N-alkyl hydroxylamine in a high yield under a mild condition by a simple method, does not require a strict time management and is advantageous for industrial-scale production. SOLUTION: The method for producing an N-alkyl hydroxylamine includes bringing an N-alkyl nitro compound into contact with a hydrogen source in the presence of a solid catalyst supporting palladium on silica and in the absence of a significant quantity of a fourth reaction component. The method for producing an N-alkyl hydroxylamine includes bringing (A) an N-alkyl nitro compound into contact only with (B) a hydrogen source and (C) a solid catalyst supporting palladium on silica, or bringing (A) an N-alkyl nitro compound into contact only with (B) a hydrogen source, (C) a solid catalyst supporting palladium on silica and (D) a solvent that does not deactivate catalytic activity and has a pKa of ≥12. COPYRIGHT: (C)2012,JPOandINPIT
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Paragraph 0089-0090
(2018/12/01)
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- Asymmetric Amination of Secondary Alcohols by using a Redox-Neutral Two-Enzyme Cascade
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Multienzyme cascade approaches for the synthesis of optically pure molecules from simple achiral compounds are desired. Herein, a cofactor self-sufficient cascade protocol for the asymmetric amination of racemic secondary alcohols to the corresponding chiral amines was successfully constructed by employing an alcohol dehydrogenase and a newly developed amine dehydrogenase. The compatibility and the identical cofactor dependence of the two enzymes led to an ingenious in situ cofactor recycling system in the one-pot synthesis. The artificial redox-neutral cascade process allowed the transformation of racemic secondary alcohols into enantiopure amines with considerable conversions (up to 94 %) and >99 % enantiomeric excess at the expense of only ammonia; this method thus represents a concise and efficient route for the asymmetric synthesis of chiral amines. If you know what amine: A redox-neutral two-enzyme cascade encompassing an alcohol dehydrogenase (ADH) and an amine dehydrogenase (AmDH) is constructed for the synthesis of chiral amines from the corresponding racemic alcohols in one pot to afford considerable conversions (up to 94 %) and high enantiomeric excess values (>99 %) at the expense of only ammonia.
- Chen, Fei-Fei,Liu, You-Yan,Zheng, Gao-Wei,Xu, Jian-He
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p. 3838 - 3841
(2016/01/26)
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- Direct amination of bio-alcohols using ammonia
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A slightly adapted catalyst system has been successfully applied in the direct amination of primary and secondary alcohols. Moreover, the applicability to diols has been shown, giving high selectivity towards the primary diamines. It was found that the Ru/P ratio as well as the amount of ammonia used are highly important in this system, especially for higher substrate loadings. The catalyst was employed on a larger batch scale for the conversion of isomannide to the corresponding diamine. Additionally, it was shown that the catalyst is stable for at least six consecutive runs. No significant loss of activity and selectivity was observed.
- Pingen, Dennis,Diebolt, Olivier,Vogt, Dieter
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p. 2905 - 2912
(2013/10/21)
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- Artificial multi-enzyme networks for the asymmetric amination of sec-alcohols
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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
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p. 4030 - 4035
(2013/04/10)
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- BENZIMIDAZOLE DERIVATIVES AS ANTIVIRAL AGENTS
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Provided are compounds of Formulas I, II, III, IV, V, and pharmaceutically acceptable salts thereof, their pharmaceutical compositions, their methods of preparation, and their use for treating viral infections mediated by a member of the Flaviviridae family of viruses such as hepatitis C virus (HCV).
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Page/Page column 220
(2013/02/28)
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- Highly efficient one step synthesis of primary amines from B-Chlorodialkylboranes
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A convenient and simple method for synthesis of primary amines has been developed by direct amination of B-Chlorodialkylboranes. This general procedure has been applied to synthesize acyclic, cyclic, hindered and chiral amines in very high yields using both hydroxylamine-O-sulfonic acid and monochloroamine as reagents.
- Malhotra, Sanjay V.,Brown, Herbert C.
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experimental part
p. 383 - 385
(2012/08/28)
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- Efficient and selective room-temperature gold-catalyzed reduction of nitro compounds with CO and H2O as the hydrogen source
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[Chemical equation presented] Taking hydrogen from water: Gold catalysis enabled the selective reduction of nitro compounds under very mild conditions with a combination of H2O and CO as the reductant (see scheme). This environmentally friendly reaction proceeded in high yield and with high chemoselectivity in the presence of a wide range of functional groups
- He, Lin,Wang, Lu-Cun,Sun, Hao,Ni, Ji,Cao, Yong,He, Yong,Fan, Kang-Nian
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supporting information; experimental part
p. 9538 - 9541
(2010/03/24)
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- Scandium(III) catalysis of transimination reactions. Independent and constitutionally coupled reversible processes
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Sc(OTf)3 efficiently catalyzes the self-sufficient transimination reaction between various types of C=N bonds in organic solvents, with turnover frequencies up to 3600 h-1 and rate accelerations up to 6 × 105. The mechanism of the crossover reaction in mixtures of amines and imines is studied, comparing parallel individual reactions with coupled equilibria. The intrinsic kinetic parameters for isolated reactions cannot simply be added up when several components are mixed, and the behavior of the system agrees with the presence of a unique mediator that constitutes the core of a network of competing reactions. In mixed systems, every single amine or imine competes for the same central hub, in accordance with their binding affinity for the catalyst metal ion center. More generally, the study extends the basic principles of constitutional dynamic chemistry to interconnected chemical transformations and provides a step toward dynamic systems of increasing complexity.
- Giuseppone, Nicolas,Schmitt, Jean-Louis,Schwartz, Evan,Lehn, Jean-Marie
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p. 5528 - 5539
(2007/10/03)
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- Indium Mediated Reduction of Nitro and Azide Groups in the Presence of HCl in Aqueous Media
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Indium mediated reduction of azide and nitro groups in the presence of HCl (1.5 equiv based on indium) at room temperature in aqueous THF successfully provided the corresponding amine in high to quantitative yields. Under the some reaction conditions, selective reduction of azide and nitro group in the presence of vinyl group could be accomplished.
- Lee, Jung Gyu,Choi, Kyung Il,Koh, Hun Yeong,Kim, Youseung,Kang, Yonghan,Cho, Yong Seo
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- A facile procedure for reduction of azides to amines with aluminium triiodide
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It has been demonstrated that a wide variety of aromatic and aliphatic azides can be efficiently reduced to the corresponding amines in good yields with freshly prepared aluminium triiodide. Other functional groups such as ether, ester, nitro and halides remain uneffected.
- Barua, Apurba,Bez, Ghanashyam,Barua, Nabin C.
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p. 128 - 129
(2007/10/03)
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- Iodotrimethylsilane: A mild and efficient reagent for the reduction of azides to amines
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Chlorotrimethylsilane - sodium iodide reagent (in situ generation of iodotrimethylsilane) in acetonitrile reduces alkyl and aryl/aroyl azides to the corresponding amines/amides in excellent yields under neutral and mild conditions.
- Kamal, Ahmed,Rao, N. Venugopal,Laxman
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p. 6945 - 6948
(2007/10/03)
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- Very Soluble and Photostable Perylene Fluorescent Dyes
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The synthesis of perylene dyes 2 with two terminal alkyl groups is described.Long-chain alkyl groups do not increase, but diminish solubility.Cycloalkyl substituents give a minimum of solubility with medium sized rings and a maximum with the cyclotetradecyl derivative (2p).Very high solubility in organic solvents is attained by substitution with secondary alkyl residues having two long chains.One of them, the dye with the 1-hexylheptyl substituent (2v), exhibits a solubility of more than 100g/l in most solvents, a fluorescent quantum yield of about 100 percent, and a very high photostability, thus making it suitable for special applications.
- Demming, Stefan,Langhals, Heinz
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p. 225 - 230
(2007/10/02)
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