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An Integrated Cofactor/Co-Product Recycling Cascade for the Biosynthesis of Nylon Monomers from Cycloalkylamines
We report a highly atom-efficient integrated cofactor/co-product recycling cascade employing cycloalkylamines as multifaceted starting materials for the synthesis of nylon building blocks. Reactions using E. coli whole cells as well as purified enzymes produced excellent conversions ranging from >80 and 95 % into desired ω-amino acids, respectively with varying substrate concentrations. The applicability of this tandem biocatalytic cascade was demonstrated to produce the corresponding lactams by employing engineered biocatalysts. For instance, ?-caprolactam, a valuable polymer building block was synthesized with 75 % conversion from 10 mM cyclohexylamine by employing whole-cell biocatalysts. This cascade could be an alternative for bio-based production of ω-amino acids and corresponding lactam compounds.
Sarak, Sharad,Sung, Sihyong,Jeon, Hyunwoo,Patil, Mahesh D.,Khobragade, Taresh P.,Pagar, Amol D.,Dawson, Philip E.,Yun, Hyungdon
p. 3481 - 3486
(2020/12/17)

En Route to a Heterogeneous Catalytic Direct Peptide Bond Formation by Zr-Based Metal-Organic Framework Catalysts
Peptide bond formation is a challenging, environmentally and economically demanding transformation. Catalysis is key to circumvent current bottlenecks. To date, many homogeneous catalysts able to provide synthetically useful methods have been developed, while heterogeneous catalysts remain largely restricted to the studies addressing the prebiotic formation of peptides. Here, the catalytic activity of Zr6-based metal-organic frameworks (Zr-MOFs) toward peptide bond formation is investigated using dipeptide cyclization as a model reaction. Unlike previous catalysts, Zr-MOFs largely tolerate water, and reactions are carried out under ambient conditions. Notably, the catalyst is recyclable and no additives to activate the COOH group are necessary, which are common limitations of previous methods. In addition, a broad reaction scope tolerates substrates with bulky and Lewis basic groups. The reaction mechanism was assessed by detailed mechanistic and computational studies and features a Lewis acid activation of carboxylate groups by Zr centers toward amine addition in which an alkoxy ligand on adjacent Zr sites assists in lowering the barrier of key proton transfers. The proposed concepts were also used to study the formation of intermolecular peptide bond formation. While intrinsic challenges associated with the catalyst structure and water removal limit a more general intermolecular reaction scope under current conditions, the results suggest that further design of Zr-MOF catalysts could render these materials broadly useful as heterogeneous catalysts for this challenging transformation.
Conic, Dragan,De Azambuja, Francisco,Harvey, Jeremy N.,Loosen, Alexandra,Parac-Vogt, Tatjana N.,Van Den Besselaar, Maxime
p. 7647 - 7658
(2021/06/30)

PRODUCTION METHOD OF CYCLIC COMPOUND
PROBLEM TO BE SOLVED: To provide an industrially simple production method of a cyclic compound. SOLUTION: A production method of a cyclic compound includes a step to obtain a reduced form (B) by reducing an unsaturated bond in a ring structure of an aromatic compound (A) by means of catalytic hydrogenation of the aromatic compound (A) or its salt using palladium carbon as a catalyst under a normal pressure, in which the aromatic compound (A) has one or more ring structures selected from a group consisting of a five membered-ring, a six membered-ring, and a condensed ring of the five membered-ring or the six membered-ring with another six membered-ring, a hetero atom can be included in the ring structure, and the aromatic compound (A) can have one or two side chains bonded to the ring structure and does not have any carbon-carbon triple bond in the side chain. SELECTED DRAWING: None COPYRIGHT: (C)2021,JPOandINPIT
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(2021/05/05)

Rapid and Mild Lactamization Using Highly Electrophilic Triphosgene in a Microflow Reactor
Lactams are cyclic amides that are indispensable as drugs and as drug candidates. Conventional lactamization includes acid-mediated and coupling-agent-mediated approaches that suffer from narrow substrate scope, much waste, and/or high cost. Inexpensive, less-wasteful approaches mediated by highly electrophilic reagents are attractive, but there is an imminent risk of side reactions. Herein, a methods using highly electrophilic triphosgene in a microflow reactor that accomplishes rapid (0.5–10 s), mild, inexpensive, and less-wasteful lactamization are described. Methods A and B, which use N-methylmorpholine and N-methylimidazole, respectively, were developed. Various lactams and a cyclic peptide containing acid- and/or heat-labile functional groups were synthesized in good to high yields without the need for tedious purification. Undesired reactions were successfully suppressed, and the risk of handling triphosgene was minimized by the use of microflow technology.
Fuse, Shinichiro,Komuro, Keiji,Otake, Yuma,Masui, Hisashi,Nakamura, Hiroyuki
supporting information
p. 7525 - 7532
(2021/03/17)

The benzyl can be selectively removed by visible light or near visible light. Method for protecting allyl and propargyl group
The invention provides a method for selectively removing benzyl, allyl and propargyl protecting groups by visible light or near visible light, namely a substrate containing benzyl, allyl or propargyl protecting groups. The method has the advantages of simple operation, safe and clean visible light or near visible light as excitation conditions, cheap and easily available reagents, high reaction yield, high reaction chemistry and regional selectivity, and is suitable for selective removal of benzyl, allyl and propargyl protecting groups in various substrates.
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Paragraph 0010

(2021/10/16)

Synthetic method 2-3 -dichloropyridine (by machine translation)
The invention provides 2-3 -dichloropyridine synthesis method which comprises the following steps: reacting cyclopentanone with hydroxylamine hydrochloride to obtain compound A; compound A under the action of ammonium chloride to obtain compound C; compound C under the action of ammonium chloride to obtain compound D; compound E reacts with chlorine to obtain compound E; compound E and tert-butylphosphinic acid ester are reacted to obtain 2, 3 - dichloropyridines. The method has the advantages of simple operation steps, cheap and easily available reaction raw materials, 68.88%% of total molar yield, 2 or more purity 3 - 98.0% -dichloropyridine, and good product quality, and is suitable for industrial production. (by machine translation)
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(2020/09/16)

Can Heteroarenes/Arenes Be Hydrogenated Over Catalytic Pd/C Under Ambient Conditions?
Hydrogenation of over a dozen aromatic compounds, including both heteroarenes and arenes, over palladium on carbon (Pd/C, 1–100 molpercent) with H2-balloon pressure at room temperature is reported. Analyses using pyridine as a model substrate revealed that acetic acid was the best solvent, as using only 1 molpercent Pd/C provided piperidine quantitatively. Substrate scope analysis and density functional theory calculations indicated that reaction rates are highly dependent on frontier molecular orbital characteristics and the steric bulkiness of substituents. Moreover, the established method was used for the concise synthesis of the anti-Alzheimer drug donepezil (Aricept?).
Tanaka, Nao,Usuki, Toyonobu
p. 5514 - 5522
(2020/07/24)

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

Well-defined N-heterocyclic carbene/ruthenium complexes for the alcohol amidation with amines: The dual role of cesium carbonate and improved activities applying an added ligand
Dehydrogenative amide bond formation from alcohols and amines has been regarded as an atom-economic and sustainable process. Among various catalytic systems, N-heterocyclic carbene (NHC)-based Ru catalytic systems have attracted growing interest due to the outstanding properties of NHCs as ligands. Herein, an NHC/Ru complex (1) was prepared and its structure was further confirmed with X-ray crystallography. In the presence of Cs2CO3, two NHC/Ru-based catalytic systems were disclosed to be active for this amide synthesis. System A, which did not contain any added ligand, required a catalyst loading of 1.00 mol%. Interestingly, improved catalytic performance was realized by the addition of an NHC precursor (L). Optimization of the amounts of L and other conditions gave rise to system B, a much more potent system with the Ru loading as low as 0.25 mol%. Moreover, an NHC-Ru-carbonate complex 6 was identified from the refluxing toluene of 1 and Cs2CO3, and further investigations revealed that 6 was an important intermediate for this catalytic reaction. Based on the above results, we claimed that the role of Cs2CO3 was to facilitate the formation of key intermediate 6. On the other hand, it provided the optimized basicity for the selective amide formation.
Wang, Wan-Qiang,Yuan, Ye,Miao, Yang,Yu, Bao-Yi,Wang, Hua-Jing,Wang, Zhi-Qin,Sang, Wei,Chen, Cheng,Verpoort, Francis
(2019/12/24)

Water-Tolerant and Atom Economical Amide Bond Formation by Metal-Substituted Polyoxometalate Catalysts
A simple, safe, and inexpensive amide bond formation directly from nonactivated carboxylic acids and free amines is presented in this work. Readily available Zr(IV)- and Hf(IV)-substituted polyoxometalates (POM) are shown to be catalysts for the amide bond formation reaction under mild conditions, low catalyst loading, and without the use of water scavengers, dry solvents, additives for facilitating the amine attack, or specialized experimental setups commonly employed to remove water. Detailed mechanistic investigations revealed the key role of POM scaffolds which act as inorganic ligands to protect Zr(IV) and Hf(IV) Lewis acidic metals against hydrolysis and preserve their catalytic activity in amide bond formation reactions. The catalysts are compatible with a range of functional groups and heterocycles useful for medicinal, agrochemical, and material chemists. The robustness of the Lewis acid-POM complexes is further supported by the catalyst reuse without loss of activity. This prolific combination of Zr(IV)/Hf(IV) and POMs inaugurates a powerful class of catalysts for the amide bond formation, which overcomes key limitations of previously established Zr(IV)/Hf(IV) salts and boron-based catalysts.
De Azambuja, Francisco,Parac-Vogt, Tatjana N.
p. 10245 - 10252
(2019/11/03)

Platinum-(phosphinito-phosphinous acid) complexes as bi-talented catalysts for oxidative fragmentation of piperidinols: An entry to primary amines
Platinum-(phosphinito-phosphinous acid) complex catalyzes the oxidative fragmentation of hindered piperidinols according to a hydrogen transfer induced methodology. This catalyst acts successively as both a hydrogen carrier and soft Lewis acid in a one pot-two steps process. This method can be applied to the synthesis of a wide variety of primary amines in a pure form by a simple acid-base extraction without further purification.
Membrat, Romain,Vasseur, Alexandre,Moraleda, Delphine,Michaud-Chevallier, Sabine,Martinez, Alexandre,Giordano, Laurent,Nuel, Didier
p. 37825 - 37829
(2019/12/03)

Iron-catalyzed oxidative functionalization of C(sp3)-H bonds under bromide-synergized mild conditions
An efficient oxidation and functionalization of C-H bonds with an inorganic-ligand supported iron catalyst and hydrogen peroxide to prepare the corresponding ketones was achieved using the bromide ion as a promoter. Preliminary mechanistic investigations indicated that the bromide ion can bind to FeMo6 to form a supramolecular species (FeMo6·2Br), which can effectively catalyze the reaction.
Yu, Han,Zhao, Qixin,Wei, Zheyu,Wu, Zhikang,Li, Qi,Han, Sheng,Wei, Yongge
supporting information
p. 7840 - 7843
(2019/07/12)

A Diaminopropane Diolefin Ru(0) Complex Catalyzes Hydrogenation and Dehydrogenation Reactions
New ruthenium (0) complexes with a cooperative diolefin diaminopropane (DAP) or the dehydrogenated iminopropenamide ligand (IPA) were synthesized for comparison with their diaminoethane (DAE)/ diazadiene (DAD) ruthenium analogues. These DAP/IPA complexes are efficient catalysts in dehydrogenation reactions of alkaline aqueous methanol which proceeds under mild conditions (T=70 °C) and of higher alcohols, forming the corresponding carbonate and carboxylates, respectively. The scope of the reaction includes an example of a 1,2-diol as model for biomass derived alcohols. Their catalytic applications are extended to the atom-efficient dehydrogenative coupling of alcohols and amines to amides. The reaction proceeds without any additives and is applicable to the synthesis of formamides from methanol. Moreover, DAP/IPA complexes catalyze the hydrogenation of a series of esters, lactone, ketone, activated olefin, aldehyde and imine substrates. The diaminopropane Ru catalyst exhibits higher activity compared to the dehydrogenated β-ketiminate (IPA) and previously studied DAD/DAE based catalysts. We present studies on their stoichiometric reactivity with relevance to their possible catalytic mechanisms and the isolation and full characterization of key reaction intermediates.
Casas, Fernando,Trincado, Monica,Rodriguez-Lugo, Rafael,Baneerje, Dipshikha,Grützmacher, Hansj?rg
p. 5241 - 5251
(2019/11/16)

Mild, calcium catalysed Beckmann rearrangements
A mild calcium catalysed Beckmann rearrangement has been realised, which forgoes the more traditional harsh reactions conditions associated with the transformation. The catalyst system is shown to be tolerant towards a wide variety of functional groups relevant to natural product synthesis and medicinal chemistry and the synthetic utility of the reaction has also been investigated. A preliminary mechanistic investigation was performed to understand the nature of the incoming nucleophile and a possible reaction pathway is described.
Kiely-Collins,Sechi,Brennan,McLaughlin
supporting information
p. 654 - 657
(2018/02/06)

An Efficient Two-Step Preparation of α-, β-, γ- or δ-Amino Acids from 2-Pyrazinones, 2-Hydroxypyrimidines or 2-Pyridones Respectively
A practical and efficient two-step procedure is reported for the preparation of a variety of α-, β-, γ- and δ-amino acids from 2-pyridone, 2-pyrazinone or 2-hydroxypyrimidine and derivatives. The procedure is amenable to scale-up and in most cases no chromatographic purification of the product is required. This approach is useful, especially in the synthesis of amino acids or deuterated amino acids that are not obtained by other methods.
Zacharie, Boulos,Abbott, Shaun D.,Baigent, Christopher B.,Doyle, Christopher,Yalagala, Ravi Shekar
p. 6486 - 6493
(2018/11/23)

A copper-catalyzed carbonylative four-component reaction of ethene and aliphatic olefins
To have a balance between reactivity and selectivity has been a long-standing challenge in multicomponent reactions. In this communication, a carbonylative four-component reaction has been developed. With copper as the catalyst, using ethene including other aliphatic alkenes, alcohols and acetonitrile as the substrates under CO pressure, various desired products were produced in moderate to good yields. The obtained products can be applied in the synthesis of δ-valerolactams. Good functional group tolerance and reaction efficiency can be observed here.
Li, Yahui,Zhu, Fengxiang,Wang, Zechao,Wu, Xiao-Feng
supporting information
p. 1984 - 1987
(2018/03/01)

Ruthenium-based catalytic systems incorporating a labile cyclooctadiene ligand with N-heterocyclic carbene precursors for the atom-economic alcohol amidation using amines
Transition-metal-catalyzed amide-bond formation from alcohols and amines is an atom-economic and eco-friendly route. Herein, we identified a highly active in situ N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic system for this amide synthesis. Various substrates, including sterically hindered ones, could be directly transformed into the corresponding amides with the catalyst loading as low as 0.25 mol.%. In this system, we replaced the p-cymene ligand of the Ru source with a relatively labile cyclooctadiene (cod) ligand so as to more efficiently obtain the corresponding poly-carbene Ru species. Expectedly, the weaker cod ligand could be more easily substituted with multiple mono-NHC ligands. Further high-resolution mass spectrometry (HRMS) analyses revealed that two tetra-carbene complexes were probably generated from the in situ catalytic system.
Chen, Cheng,Miao, Yang,De Winter, Kimmy,Wang, Hua-Jing,Demeyere, Patrick,Yuan, Ye,Verpoort, Francis
(2018/09/29)

Efficient N-Heterocyclic Carbene/Ruthenium Catalytic Systems for the Alcohol Amidation with Amines: Involvement of Poly-Carbene Complexes?
The atom-economic direct amidation of alcohols with amines has been recently highlighted as an attractive and promising transformation. Among the versatile reported catalytic systems, in situ generated N-heterocyclic carbene (NHC)/ruthenium (Ru) catalytic systems have demonstrated their advantages such as easy operation and use of commercial Ru compounds. However, the existing catalyst loadings are relatively high, and additional insights for the in situ catalyst generation are still not well-documented. In this work, a variety of benzimidazole-based NHC precursors were initially synthesized. Through the screening of various NHC precursors and other reaction conditions, active in situ catalytic systems were discovered for the efficient amide synthesis. Notably, the catalyst loading is as low as 0.5 mol %. Furthermore, additional experiments were performed to validate the rationale for the superiority of the current catalytic systems over our previous system. It was observed that the ligand structure is one of the reasons for the higher activity. In addition, the higher ratio of the NHC precursor/[Ru] is another important factor for the improvement. Further HR-MS analysis identified the formation of two mono-NHC-Ru species as major species and two Ru species bearing multiple NHC ligands as minor species. Hopefully, the efficient and readily-accessible catalytic systems reported herein could demonstrate great potential for further practical applications.
Cheng, Hua,Xiong, Mao-Qian,Zhang, Ni,Wang, Hua-Jing,Miao, Yang,Su, Wei,Yuan, Ye,Chen, Cheng,Verpoort, Francis
p. 4338 - 4345
(2018/09/06)

In situ Generated Ruthenium Catalyst Systems Bearing Diverse N-Heterocyclic Carbene Precursors for Atom-Economic Amide Synthesis from Alcohols and Amines
The transition-metal-catalyzed direct synthesis of amides from alcohols and amines is herein demonstrated as a highly environmentally benign and atom-economic process. Among various catalyst systems, in situ generated N-heterocyclic carbene (NHC)-based ruthenium (Ru) halide catalyst systems have been proven to be active for this transformation. However, these existing catalyst systems usually require an additional ligand to achieve satisfactory results. In this work, through extensive screening of a diverse variety of NHC precursors, we discovered an active in situ catalyst system for efficient amide synthesis without any additional ligand. Notably, this catalyst system was found to be insensitive to the electronic effects of the substrates, and various electron-deficient substrates, which were not highly reactive with our previous catalyst systems, could be employed to afford the corresponding amides efficiently. Furthermore, mechanistic investigations were performed to provide a rationale for the high activity of the optimized catalyst system. NMR-scale reactions indicated that the rapid formation of a Ru hydride intermediate (signal at δ=?7.8 ppm in the 1H NMR spectrum) after the addition of the alcohol substrate should be pivotal in establishing the high catalyst activity. Besides, HRMS analysis provided possible structures of the in situ generated catalyst system.
Cheng, Hua,Xiong, Mao-Qian,Cheng, Chuan-Xiang,Wang, Hua-Jing,Lu, Qiang,Liu, Hong-Fu,Yao, Fu-Bin,Chen, Cheng,Verpoort, Francis
p. 440 - 448
(2018/02/06)

Dehydrogenative Oxidation of Cyclic Amines on a Diruthenium Complex
The dehydrogenative oxidation of cyclic amines catalyzed by a diruthenium complex and mechanistic studies are described. Cyclic amines and water reacted in the presence of Cp?Ru(μ-H)4RuCp? (1) (Cp? = 1,2,4-tri-tert-butylcyclopentadienyl) to afford lactams accompanied by elimination of the hydrogen gas. The reaction of hexamethylenimine with 1 at 160 °C afforded Cp?Ru(μ-H)2(μ-C6H11N)RuCp? (2), having a novel μ-cyclic imine ligand through N-H and C-H bond cleavages. Further C-H bond cleavage of 2 proceeded at 180 °C to afford Cp?Ru(μ-H)(μ-η2:η2-C6H10N)RuCp? (4), having a perpendicularly coordinated imidoyl ligand. Complex 4 readily reacted with water and liberated -caprolactam. The cooperative interaction of the two ruthenium atoms leading to N-H and double C-H bond cleavages was the key to the dehydrogenative oxidation of cyclic amines.
Shimogawa, Ryuichi,Fujita, Ryosuke,Takao, Toshiro,Suzuki, Hiroharu
supporting information
p. 1893 - 1896
(2017/06/13)

A HOST CELL MODIFIED TO PRODUCE LACTAMS
The present invention provides for a genetically modified host cell capable of producing a lactam comprising a 2-pyrrolidone synthase, or an enzymatically active fragment thereof, heterologous to the host cell.
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Paragraph 0015; 00100

(2018/01/15)

Strong influence of intramolecular Si?O proximity on reactivity: Systematic molecular structure, solvolysis, and mechanistic study of cyclic N-trimethylsilyl carboxamide derivatives
A comparative alcoholysis study of N-silylated derivatives of simple heterocyclic carboxamides (lactams, imides, ureas) is presented. The second-order rate constant values span a range as wide as three orders of magnitude. On the basis of DFT calculations, a good correlation between reactivity and the Si?O distance was found within each family of compounds. The viability of two different reaction pathways was evaluated using a detailed computational mechanistic study of the methanolysis of cyclic urea homologues. Peculiarities in the single-crystal X-ray diffraction structures of the trimethylsilyl and trimethylsiloxy phthalimides are also discussed.
Szalay, Roland,Harmat, Veronika,E?ri, János,Pongor, Gábor
p. 2186 - 2192
(2017/05/16)

One-pot conversion of cyclohexanol to ?-caprolactam using a multifunctional Na2WO4-acidic ionic liquid catalytic system
Na2WO4-acidic ionic liquid was used as a simple, ecofriendly, recyclable and efficient catalytic system for the one-pot conversion of cyclohexanol to ?-caprolactam. The effect of the structure of the ionic liquid on the catalytic activity of this system was investigated, and the results revealed that sulfonic acid-functionalized ionic liquids with HSO4?as an anion gave the best results. The highly efficient performance of this catalyst system was attributed to the phase-transfer behavior of the cation of the ionic liquid, the improved coordination of the substrate to bisperoxotungstate during the oxidation reaction, and the stabilization of the intermediate formed during the Beckmann rearrangement.
Wang, Hefang,Jia, Liyuan,Hu, Rongbin,Gao, Meidan,Wang, Yanji
p. 58 - 64
(2017/01/28)

MANGANESE BASED COMPLEXES AND USES THEREOF FOR HOMOGENEOUS CATALYSIS
The present invention relates to novel manganese complexes and their use, inter alia, for homogeneous catalysis in (1) the preparation of imine by dehydrogenative coupling of an alcohol and amine; (2) C-C coupling in Michael addition reaction using nitriles as Michael donors; (3) dehydrogenative coupling of alcohols to give esters and hydrogen gas (4) hydrogenation of esters to form alcohols (including hydrogenation of cyclic esters (lactones) or cyclic di-esters (di- lactones), or polyesters); (5) hydrogenation of amides (including cyclic dipeptides, lactams, diamide, polypeptides and polyamides) to alcohols and amines (or diamine); (6) hydrogenation of organic carbonates (including polycarbonates) to alcohols or hydrogenation of carbamates (including polycarbamates) or urea derivatives to alcohols and amines; (7) dehydrogenation of secondary alcohols to ketones; (8) amidation of esters (i.e., synthesis of amides from esters and amines); (9) acylation of alcohols using esters; (10) coupling of alcohols with water and a base to form carboxylic acids; and (11) preparation of amino acids or their salts by coupling of amino alcohols with water and a base. (12) preparation of amides (including formamides, cyclic dipeptides, diamide, lactams, polypeptides and polyamides) by dehydrogenative coupling of alcohols and amines; (13) preparation of imides from diols.
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Paragraph 00388-00389

(2017/09/05)

High-Temperature Boc Deprotection in Flow and Its Application in Multistep Reaction Sequences
A simplified Boc deprotection using a high-temperature flow reactor is described. The system afforded the qualitative yield of a wide variety of deprotected substrates within minutes using acetonitrile as the solvent and without the use of acidic conditions or additional workups. Highly efficient, multistep reaction sequences in flow are also demonstrated wherein no extraction or isolation was required between steps.
Bogdan, Andrew R.,Charaschanya, Manwika,Dombrowski, Amanda W.,Wang, Ying,Djuric, Stevan W.
supporting information
p. 1732 - 1735
(2016/05/19)

Aerobic Oxidation of Cyclic Amines to Lactams Catalyzed by Ceria-Supported Nanogold
Abstract: The oxidative transformation of cyclic amines to lactams, which are important chemical feedstocks, is efficiently catalyzed by CeO2-supported gold nanoparticles (Au/CeO2) and Aerosil 200 in the presence of an atmosphere of O2. The complete conversion of pyrrolidine was achieved in 6.5?h at 160 °C, affording a 97 % yield of the lactam product 2-pyrrolidone (γ-butyrolactam), while 2-piperidone (δ-valerolactam) was synthesized from piperidine (83 % yield) in 2.5?h. Caprolactam, the precursor to the commercially important nylon-6, was obtained from hexamethyleneimine in 37 % yield in 3?h. During the oxidation of pyrrolidine, two transient species, 5-(pyrrolidin-1-yl)-3,4-dihydro-2H-pyrrole (amidine-5) and 4-amino-1-(pyrrolidin-1-yl)butan-1-one, were observed. Both of these compounds were oxidized to 2-pyrrolidone under catalytic conditions, indicating their role as intermediates in the reaction pathway. In addition to the reactions of cyclic secondary amines, Au/CeO2 also efficiently catalyzes the oxidation of N-methyl cyclic tertiary amines to the corresponding lactams at 80 and 100 °C. Graphical Abstract: [Figure not available: see fulltext.]
Dairo, Taiwo O.,Nelson, Nicholas C.,Slowing, Igor I.,Angelici, Robert J.,Woo, L. Keith
p. 2278 - 2291
(2016/11/09)

Supported Gold Nanoparticles for Efficient α-Oxygenation of Secondary and Tertiary Amines into Amides
Although the α-oxygenation of amines is a highly attractive method for the synthesis of amides, efficient catalysts suited to a wide range of secondary and tertiary alkyl amines using O2as the terminal oxidant have no precedent. This report describes a novel, green α-oxygenation of a wide range of linear and cyclic secondary and tertiary amines mediated by gold nanoparticles supported on alumina (Au/Al2O3). The observed catalysis was truly heterogeneous, and the catalyst could be reused. The present α-oxygenation utilizes O2as the terminal oxidant and water as the oxygen atom source of amides. The method generates water as the only theoretical by-product, which highlights the environmentally benign nature of the present reaction. Additionally, the present α-oxygenation provides a convenient method for the synthesis of18O-labeled amides using H218O as the oxygen source.
Jin, Xiongjie,Kataoka, Kengo,Yatabe, Takafumi,Yamaguchi, Kazuya,Mizuno, Noritaka
supporting information
p. 7212 - 7217
(2016/07/06)

PIPERIDINE DERIVATIVE, LIQUID CRYSTAL COMPOSITION AND LIQUID CRYSTAL DISPLAY DEVICE
To provide a compound having an effect for preventing photolysis of a liquid crystal composition, and having a high solubility in the liquid crystal composition, a liquid crystal composition containing the compound, and a liquid crystal display device including the composition. The compound is represented by formula (1), a liquid crystal composition contains the compound, and a liquid crystal display device includes the composition: [in-line-formulae]M(Z-Q)a(Rb)b??(1)[/in-line-formulae] wherein, in formula (1), a is 1 to 4, and b is a numerical value: (4?a); M is an organic group; Z is a single bond or the like; and Q is a monovalent group represented by formula (Q-1), (Q-2) or (Q-3), in which Ra and Rb are hydrogen, alkyl or the like.
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(2016/04/26)

Dehydration of 5-amino-1-pentanol over rare earth oxides
Vapor-phase catalytic dehydration of 5-amino-1-pentanol was investigated over various oxide catalysts including rare earth oxides (REOs). Over ordinary acidic oxides such as Al2O3, SiO2, SiO2-Al2O3, TiO2, and ZrO2, a cyclic amine such as piperidine was mainly produced at temperatures of 300 °C and higher. In contrast, basic REOs with a cubic bixbyite structure showed the catalytic activity in the conversion of 5-amino-1-pentanol to produce 4-penten-1-amine at 425 °C. In REO catalysts, Tm2O3, Yb2O3, and Lu2O3 showed the high conversion of 5-amino-1-pentanol and the high selectivity to 4-penten-1-amine. Especially, Yb2O3 calcined at 800 °C showed a high formation rate of 4-penten-1-amine with the selectivity of ca. 90% at 425 °C. In comparing the reactivity of several amino alcohols to form the corresponding unsaturated amines, Yb2O3 effectively catalyzed the dehydration of 6-amino-1-hexanol into 5-hexen-1-amine, whereas 3-amino-1-propanol and 4-amino-1-butanol were not effectively dehydrated due to the decomposition of the reactant.
Ohta, Kaishu,Yamada, Yasuhiro,Sato, Satoshi
p. 73 - 80
(2016/04/05)

In situ functionalized sulfonic copolymer toward recyclable heterogeneous catalyst for efficient Beckmann rearrangement of cyclohexanone oxime
Exploring environmentally friendly, efficient and recyclable heterogeneous catalysts for low-temperature liquid-phase organic reactions are important for the development of green and sustainable processes. In this work, we applied an in situ sulfonated polymeric solid acid H-PDVB-SO3H for catalyzing liquid-phase Beckmann rearrangements for the first time, with post-sulfonated sample and other various counterparts as control catalysts. H-PDVB-SO3H was prepared by copolymerization of divinylbenzene with sodium p-styrene sulfonate under solvothermal condition, followed by ion-exchanging to convert the polymer into proton form. It possessed a large surface area, plenty of mesopores and high sulfur content, and exhibited the high yield to ε-caprolactam (75%) with quite steady reusability in the heterogeneous Beckmann rearrangement of cyclohexanone oxime. The catalyst also showed good substrate compatibility with such a high reaction rate that the reaction time was as short as 1 h. No any co-catalysts or metals were used in the catalytic system, making the catalyst an environmentally friendly and efficient candidate for Beckmann rearrangements.
Li, Difan,Mao, Dan,Li, Jing,Zhou, Yu,Wang, Jun
p. 125 - 133
(2015/12/01)

Construction of tertiary chiral centers by Pd-catalyzed asymmetric allylic alkylation of prochiral enolate equivalents
Abstract The palladium-catalyzed decarboxylative allylic alkylation of enol carbonates derived from lactams and ketones is described. Employing these substrates with an electronically tuned Pd catalyst system trisubstituted chiral centers are produced. These stereocenters have been previously challenging to achieve using Pd complex/chiral P-N ligand systems.
Kita, Yusuke,Numajiri, Yoshitaka,Okamoto, Noriko,Stoltz, Brian M.
p. 6349 - 6353
(2015/08/18)

Highly efficient synthesis of amides from ketoximes using trifluoromethanesulphonic anhydride
Trifluoromethanesulphonic anhydride (triflic anhydride: TA) has been successfully used as a reagent for Beckmann rearrangement in the conversion of a variety of ketoximes into amides without any additive or base. This reagent works well for the synthesis of a library of amides with excellent yields.
Kalkhambkar, Rajesh G.,Savanur, Hemantkumar M.
p. 60106 - 60113
(2015/07/27)

Highly Selective Hydrogenation of Aromatic Ketones and Phenols Enabled by Cyclic (Amino)(alkyl)carbene Rhodium Complexes
Air-stable Rh complexes ligated by strongly σ-donating cyclic (amino)(alkyl)carbenes (CAACs) show unique catalytic activity for the selective hydrogenation of aromatic ketones and phenols by reducing the aryl groups. The use of CAAC ligands is essential for achieving high selectivity and conversion. This method is characterized by its good compatibility with unsaturated ketones, esters, carboxylic acids, amides, and amino acids and is scalable without detriment to its efficiency.
Wei, Yu,Rao, Bin,Cong, Xuefeng,Zeng, Xiaoming
supporting information
p. 9250 - 9253
(2015/08/11)

Establishment of an activated peroxide system for low-temperature cotton bleaching using N-[4-(triethylammoniomethyl)benzoyl]butyrolactam chloride
Cotton bleaching is traditionally carried out in strongly alkaline solution of hydrogen peroxide (H2O2) at temperatures close to the boil. Such harsh processing conditions can result in extensive water and energy consumptions as well as severe chemical damage to textiles. In this study, an activated peroxide system was established for low-temperature cotton bleaching by incorporating a bleach activator, namely N-[4-(triethylammoniomethyl)benzoyl]butyrolactam chloride (TBBC) into an aqueous H2O2 solution. Experimental results showed that the TBBC-activated peroxide system exhibited the most effective bleaching performance in a pH range of 6-8 which could be approximated by adding sodium bicarbonate (NaHCO3). The TBBC/H2O2/NaHCO3 system led to rapid bleaching of cotton at a temperature as low as 50°C. In comparison with the hot alkaline peroxide bleaching system, the TBBC/H2O2/NaHCO3 system provided cotton fabric with an equivalent degree of whiteness, higher degree of polymerization, and slightly lower water absorbency. The new activated peroxide system may provide a more environmentally benign approach to cotton bleaching.
Xu, Changhai,Hinks, David,Sun, Chang,Wei, Qufu
p. 71 - 77
(2015/01/09)

Direct catalytic synthesis of ε-caprolactam from cyclohexanol using [n-C16H33N (CH3)3]H2PW12O40 as a catalyst
ε-Caprolactam was synthesized directly from cyclohexanol via a tandem catalytic process using [n-C16H33N(CH3)3]H2PW12O40 as a catalyst. The highly efficient performance of the catalysts is due to the phase-transfer function of cation, improved coordination with peroxotungsten during oxidation and stabilization function of heteropoly anion on the intermediate formed during Beckmann rearrangement. A ε-caprolactam yield of 73.9% was obtained with a cyclohexanol conversion of 97.1% under optimized conditions.
Wang, Hefang,Hu, Rongbin,Yang, Yongfang,Gao, Meidan,Wang, Yanji
p. 6 - 11
(2015/08/03)

Galactose Oxidase Variants for the Oxidation of Amino Alcohols in Enzyme Cascade Synthesis
The use of selected engineered galactose oxidase (GOase) variants for the oxidation of amino alcohols to aldehydes under mild conditions in aqueous systems is reported. GOase variant F2 catalyses the regioselective oxidation of N-carbobenzyloxy (Cbz)-protected 3-amino-1,2-propanediol to the corresponding α-hydroxyaldehyde which was then used in an aldolase reaction. Another variant, M3-5, was found to exhibit activity towards free and N-Cbz-protected aliphatic and aromatic amino alcohols allowing the synthesis of lactams such as 3,4-dihydronaphthalen-1(2H)-one, 2-pyrrolidone and valerolactam in one-pot tandem reactions with xanthine dehydrogenase (XDH) or aldehyde oxidase (PaoABC).
Herter, Susanne,McKenna, Shane M.,Frazer, Andrew R.,Leimkühler, Silke,Carnell, Andrew J.,Turner, Nicholas J.
p. 2313 - 2317
(2015/08/11)

Iron(II) pincer-catalyzed synthesis of lactones and lactams through a versatile dehydrogenative domino sequence
The synthesis of lactones and lactams by using iron(II) pincer-catalyzed dehydrogenative methodology was developed. Starting from 1,n-diols or 1,n-amino alcohols, this domino transformation takes place through initial dehydrogenation of the substrates, subsequent intramolecular cyclization, and final oxidation to afford the desired products in good yields. The ability to access heterocycles of different sizes makes this protocol especially versatile, in which two consecutive oxidation reactions are performed without requiring an external oxidant. In this paper, we report the application of the Fe-MACHO-BH complex [carbonylhydrido(tetrahydroborato)[bis(2-diisopropylphosphinoethyl)amino]iron(II)] in this atom-efficient and environmentally benign process, for which molecular hydrogen is formed as the only stoichiometric side product. Just a little pinch: The iron(II) pincer-catalyzed synthesis of lactones and lactams from easily available 1,n-diols and 1,n-amino alcohols is explored. The use of a nontoxic metal as well as the generation of molecular hydrogen as the only stoichiometric byproduct makes this method a highly atom-efficient and environmentally benign process.
Pea-Lpez, Miguel,Neumann, Helfried,Beller, Matthias
p. 865 - 871
(2015/03/14)

A mild, copper-catalysed amide deprotection strategy: Use of tert-butyl as a protecting group
Mild methods for the deprotection of organic substrates are of fundamental importance in synthetic chemistry. A new room temperature method using a catalytic amount of Cu(OTf)2is reported. This allows use of the tert-butyl group as an amide protecting group. The methodology is also extended to Boc-deprotection.
Evans, Vikki,Mahon, Mary F.,Webster, Ruth L.
supporting information
p. 7593 - 7597
(2014/12/10)

Oxidant-free conversion of cyclic amines to lactams and H2 using water as the oxygen atom source
Direct conversion of cyclic amines to lactams utilizing water as the only reagent is catalyzed by pincer complex 2. In contrast to previously known methods of amine-to-amide conversion, this reaction occurs in the absence of oxidants and is accompanied by liberation of H2, with water serving as a source of oxygen atom. Formation of a cyclic hemiaminal intermediate plays a key role in enabling such reactivity. This represents an unprecedented, conceptually new type of amide formation reaction directly from amines and water under oxidant-free conditions.
Khusnutdinova, Julia R.,Ben-David, Yehoshoa,Milstein, David
supporting information
p. 2998 - 3001
(2014/03/21)

Hexaalkylguanidinium salts as ionic liquids - Applications in titanium and aluminium alcoholate assisted synthesis
The solubility of titanium and aluminium alcoholates and of titanium tetrakis(trimethylsilanolate) in several hexaalkylguanidinium-based room temperature ionic liquids was screened. The solvent/solute combinations which displayed the highest alcoholate solubility and stability were applied as Lewis-acidic catalytic media for several dehydrating cyclocondensations: lactamisation of ω-aminocarboxylic acids, direct amidation of carboxylic acids, synthesis of oxazolines from carboxylic acids and 2-aminoethanol, lactonisation of 6-hydroxyhexanoic acid, and Paal-Knorr synthesis of pyrroles.
Arkhipova, Maria,Eichel, Svetlana,Maas, Gerhard
p. 56506 - 56517
(2015/02/05)

Keggin-type Bronsted dodecatungstophosphoric acid: A quasi homogenous and reusable catalyst system for liquid phase Beckmann rearrangement
A variety of ketoximes, prepared from corresponding ketones, undergo Beckmann rearrangement using H3PW12O40 (DTPA) in acetonitrile under reflux to yield N-substituted amides and lactams in good to excellent yields (72-96%). The present method provides an efficient, clean, eco-friendly, and simple synthesis. The catalyst is cheap, moisture tolerant, recoverable, and reusable without much loss of its activity.
Kaur, Gagandeep,Rajput, Jaspreet Kaur,Arora, Priya,Devi, Nisha
p. 1136 - 1140
(2014/02/14)

Amino-alcohol cyclization: Selective synthesis of lactams and cyclic amines from amino-alcohols
By employing an amination catalyst, previously used in the direct synthesis of amines from alcohol with ammonia, n-amino-alcohols could be selectively cyclized to either the amide or the amine. By the addition of water, the amine could be produced as the major product whereas adding a sacrificial ketone as a hydrogen acceptor resulted in the amide as the major product. Without an additive a mixture of both the amine and the amide was observed. N-substituted amino-alcohols solely gave cyclic amines under these conditions. From 2-(n-alkanol) anilines the cyclic amines were produced, where the n-propanol derivative selectively formed quinoline as the major product.
Pingen, Dennis,Vogt, Dieter
p. 47 - 52
(2014/01/06)

Synthesis of lactams by isomerization of oxindoles substituted at C-3 by an ω-amino chain
Oxindoles substituted at N-1 by electron-withdrawing groups and at C-3 by ω-amino chains of various lengths undergo mild and easy isomerization to new 5- to 12-membered lactams in good yields (30-96%). As efficient asymmetric syntheses of diversely 3,3-disubstituted oxindoles are currently developed, this isomerization provides a new and valuable access to medium-sized lactams α-substituted with a quaternary asymmetric carbon bearing a 2-aminophenyl residue.
Sarraf, Daad,Richy, Nicolas,Vidal, Jolle
p. 10945 - 10955
(2015/01/08)

Ruthenium-catalysed oxidation of alcohols to amides using a hydrogen acceptor
A wider investigation into the synthesis of secondary amides from primary alcohols using a hydrogen acceptor using commercially available [Ru(p-cymene)Cl2]2 with bis(diphenylphosphino)butane (dppb) as the catalyst. The report looks at over 50 examples with varying functionality and steric bulk, whilst also covering the first reported results using microwave heating to effect the transformation.
Watson, Andrew J.A.,Wakeham, Russell J.,Maxwell, Aoife C.,Williams, Jonathan M.J.
supporting information
p. 3683 - 3690
(2014/05/20)

Direct synthesis of amides from carboxylic acids and amines using B(OCH2CF3)3
B(OCH2CF3)3, prepared from readily available B2O3 and 2,2,2-trifluoroethanol, is as an effective reagent for the direct amidation of a variety of carboxylic acids with a broad range of amines. In most cases, the amide products can be purified by a simple filtration procedure using commercially available resins, with no need for aqueous workup or chromatography. The amidation of N-protected amino acids with both primary and secondary amines proceeds effectively, with very low levels of racemization. B(OCH2CF3)3 can also be used for the formylation of a range of amines in good to excellent yield, via transamidation of dimethylformamide.
Lanigan, Rachel M.,Starkov, Pavel,Sheppard, Tom D.
p. 4512 - 4523
(2013/06/05)

Synthesis of lactams using enzyme-catalyzed aminolysis
The formation of caprolactam from 6-aminocaproic acid catalyzed by CALB (N435) is reported. Different lactam ring sizes can be prepared starting from 4-aminobutanoic acid, 5-aminovaleric acid, and 8-aminooctanoic acid. Experiments with mixtures of aminocarboxylic acids have shown that CALB prefers homocyclization of the individual aminocarboxylic acids.
Stavila,Loos
p. 370 - 372
(2013/02/25)

Stannous chloride dihydrate-mediated efficient access to secondary and primary amides from oximes
Highly selective, efficient and expeditious Beckmann rearrangement of a wide range of ketoximes to secondary amides (20 examples) has been accomplished using stoichiometric amount of stannous chloride dihydrate in the presence of nucleophilic additive, tetra-n-butylammonium iodide (TBAI) (10 moI%) and 4 ? MS in dry acetonitrile at reflux temperature. Aldoximes delivered primary amides through intermediacy of nitriles upon heating with an equimolar amount of SnCl2·2H2O and DBU in dry toluene at reflux in good to acceptable yields (12 examples). Utilization of mild Lewis acid, inexpensive rack reagents and procedural simplicity including easy isolation of products are key advantageous features of the protocol.
Ganguly, Nemai C.,Nayek, Subhasis,Chandra, Sumanta
p. 1695 - 1702
(2014/01/17)

Heterogeneous Beckmann rearrangements catalyzed by a sulfonated imidazolium salt of phosphotungstate
The heteropolyanion-based ionic liquid (IL) material [MIMPS] 3PW12O40, propane sulfoacid-functionalized imidazolium salt of phosphotungstate, was used as a solid catalyst for liquid-phase Beckmann rearrangements of ketoximes in the presence of zinc chloride. The resultant liquid-solid biphasic rearrangement reaction of cyclohexanone oxime shows a high yield 83 % with good recyclability. The testing of control catalysts, reaction conditions, oxime substrates, and recycling property were carried out and the results are discussed. Graphical Abstract: The heteropolyanion-based ionic liquid (IL) material [MIMPS]3PW 12O40, propane sulfoacid-functionalized imidazolium salt of phosphotungstate, was used as a solid catalyst for liquid-phase Beckmann rearrangements of ketoximes in the presence of zinc chloride. The resultant liquid-solid biphasic rearrangement reaction of cyclohexanone oxime shows a high yield 83% with good recyclability. The testing of control catalysts, reaction conditions, oxime substrates, and recycling property were carried out, and the results are discussed.[Figure not available: see fulltext.]
Zhang, Xuan,Mao, Dan,Leng, Yan,Zhou, Yu,Wang, Jun
p. 193 - 199
(2013/03/13)

Kinetic and mechanistic study of N-aminopiperidine formation via the raschig process
Formation of N-aminopiperidine (NAPP) in the reaction of monochloramine with piperidine was studied by varying the reagents concentrations, pH and temperature. The study was carried out in diluted solutions, recording simultaneously monochloramine concentration by UV spectrophotometry at 243 nm and hydrazine concentration at 237 nm after treatment with formaldehyde. The presence of two competitive reactions: formation of NAPP and a complex parallel reaction limiting the yield of hydrazine, was established. Reaction products were characterized by GC/MS analysis. The rate constant of NAPP formation and activation parameters were determined, k1 = 56 × 10 -3 M-1 s-1 (25°C) and k1 = 9.3 × 106 exp(-46.5/RT) M-1 s-1, respectively. Pleiades Publishing, Ltd., 2013.
Darwich,Elkhatib,Pasquet,Delalu
p. 649 - 655
(2014/01/23)

One-pot photo-reductive N-alkylation of aniline and nitroarene derivatives with primary alcohols over Au-TiO2
We report the photo-catalytic N-alkylation of aniline by Au-TiO 2. We successfully alkylate aniline with several primary alcohols. The combined selectivities of mono- and di-alkylated products were always in excess of 70% and dependent on the alkylating alcohol used. A one-pot reaction from nitrobenzene was found to be possible with several substrates. Preliminary experiments showed that this approach could be adopted for the production of lactams using terminal amino-alcohols. The Royal Society of Chemistry 2013.
Stibal, David,Sa, Jacinto,Bokhoven, Jeroen A. Van
p. 94 - 98
(2013/04/10)