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Mechanochemical, Water-Assisted Asymmetric Transfer Hydrogenation of Ketones Using Ruthenium Catalyst
Asymmetric catalytic reactions are among the most convenient and environmentally benign methods to obtain optically pure compounds. The aim of this study was to develop a green system for the asymmetric transfer hydrogenation of ketones, applying chiral Ru catalyst in aqueous media and mechanochemical energy transmission. Using a ball mill we have optimized the milling parameters in the transfer hydrogenation of acetophenone followed by reduction of various substituted derivatives. The scope of the method was extended to carbo- and heterocyclic ketones. The scale-up of the developed system was successful, the optically enriched alcohols could be obtained in high yields. The developed mechanochemical system provides TOFs up to 168 h?1. Our present study is the first in which mechanochemically activated enantioselective transfer hydrogenations were carried out, thus, may be a useful guide for the practical synthesis of optically pure chiral secondary alcohols.
Kolcsár, Vanessza Judit,Sz?ll?si, Gy?rgy
(2022/01/04)

Asymmetric reduction of prochiral aromatic and hetero aromatic ketones using whole-cell of Lactobacillus senmaizukei biocatalyst
Asymmetric bioreduction of aromatic and heteroaromatic ketones is an important process in the production of precursors of biologically active molecules. In this study, the bioreduction of aromatic and hetero aromatic prochiral ketones into optically active alcohols was investigated using Lactobacillus senmaizukei as a whole-cell catalyst, since whole-cells are less expensive than pure enzymes. The study indicates enantioselective bioreduction of various substituted aromatic ketones (1–16) to the corresponding (R)-and (S)-chiral secondary alcohols (1a–16a) in low to excellent enantioselectivity (6–94%) with good yields (58–95%). In addition, heteroaromatic prochiral ketones 1-(pyridin-2-yl)ethanone (17) and 1-(furan-2-yl)ethanone (18) were reduced to (R)-17a and (R)-18a in enantiopure form with excellent conversion (>99%) and yields. These findings show that L. senmaizukei is a very important biocatalyst for asymmetric reduction of both 6-membered and 5-member heteroaromatic methyl ketones. This method promising a green synthesis for the synthesis of biologically important secondary chiral alcohols in an environmentally friendly and inexpensive process.
?olak, Nida Sezin,Kalay, Erbay,?ahin, Engin
p. 2305 - 2315
(2021/05/31)

Lewis Base–Br?nsted Acid–Enzyme Catalysis in Enantioselective Multistep One-Pot Syntheses
Establishing one-pot, multi-step protocols combining different types of catalysts is one important goal for increasing efficiency in modern organic synthesis. In particular, the high potential of biocatalysts still needs to be harvested. Based on an in-depth mechanistic investigation of a new organocatalytic protocol employing two catalysts {1,4-diazabicyclo[2.2.2]octane (DABCO); benzoic acid (BzOH)}, a sequence was established providing starting materials for enzymatic refinement (ene reductase; alcohol dehydrogenase): A gram-scale access to a variety of enantiopure key building blocks for natural product syntheses was enabled utilizing up to six catalytic steps within the same reaction vessel.
Giesler, Markus,Guder, Marian,Hartmann, Laura,Mantel, Marvin,Pietruszka, J?rg,Rüthlein, Elisabeth
supporting information
p. 16700 - 16706
(2021/05/07)

Synthesis and Evaluation of Non-Hydrolyzable Phospho-Lysine Peptide Mimics
The intrinsic lability of the phosphoramidate P?N bond in phosphorylated histidine (pHis), arginine (pHis) and lysine (pLys) residues is a significant challenge for the investigation of these post-translational modifications (PTMs), which gained attention rather recently. While stable mimics of pHis and pArg have contributed to study protein substrate interactions or to generate antibodies for enrichment as well as detection, no such analogue has been reported yet for pLys. This work reports the synthesis and evaluation of two pLys mimics, a phosphonate and a phosphate derivative, which can easily be incorporated into peptides using standard fluorenyl-methyloxycarbonyl- (Fmoc-)based solid-phase peptide synthesis (SPPS). In order to compare the biophysical properties of natural pLys with our synthetic mimics, the pKa values of pLys and analogues were determined in titration experiments applying nuclear magnetic resonance (NMR) spectroscopy in small model peptides. These results were used to compute electrostatic potential (ESP) surfaces obtained after molecular geometry optimization. These findings indicate the potential of the designed non-hydrolyzable, phosphonate-based mimic for pLys in various proteomic approaches.
Hauser, Anett,Poulou, Eleftheria,Müller, Fabian,Schmieder, Peter,Hackenberger, Christian P. R.
supporting information
p. 2326 - 2331
(2020/12/09)

Photo-Induced N-N Coupling of o-Nitrobenzyl Alcohols and Indolines to Give N-Aryl-1-amino Indoles
A novel method to synthesize N-aryl-1-amino indoles was established by the photoinduced N-N coupling reaction. This protocol is by treatment of o-nitrobenzyl alcohols and indolines in the presence of TEAI and acetic acid with a 24 W ultraviolet (UV) light
Ou, Yifeng,Yang, Tianbao,Tang, Niu,Yin, Shuang-Feng,Kambe, Nobuaki,Qiu, Renhua
supporting information
p. 6417 - 6422
(2021/08/30)

Chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes using carbon-supported palladium catalytic system in water
Developing and/or modifying fundamental chemical reactions using chemical industry-favorite heterogeneous recoverable catalytic systems in the water solvent is very important. In this paper, we developed convenient, green, and efficient approaches for the chemoselective reduction of nitroarenes, N-acetylation of arylamines, and one-pot reductive acetylation of nitroarenes in the presence of the recoverable heterogeneous carbon-supported palladium (Pd/C) catalytic system in water. The utilize of the simple, effective, and recoverable catalyst and also using of water as an entirely green solvent along with relatively short reaction times and good-to-excellent yields of the desired products are some of the noticeable features of the presented synthetic protocols. Graphic abstract: [Figure not available: see fulltext.].
Zeynizadeh, Behzad,Mohammad Aminzadeh, Farkhondeh,Mousavi, Hossein
p. 3289 - 3312
(2021/05/11)

Preparation method of o-nitrobenzaldehyde
The invention relates to the technical field of organic synthesis, in particular to a preparation method of o-nitrobenzaldehyde. The invention provides a preparation method of o-nitrobenzaldehyde, which comprises the following steps: (A) carrying out oxidation reaction on o-nitroethylbenzene to obtain 1-(2-nitrophenyl)ethanol; (B) carrying out oxidation reaction on the 1-(2-nitrophenyl)ethanol to obtain o-nitroacetophenone; (C) carrying out oxidation reaction on the o-nitroacetophenone to obtain the o-nitrobenzaldehyde. According to the preparation method, cheap o-nitroethylbenzene is taken as a raw material, and o-nitrobenzaldehyde is obtained through three steps of oxidation reactions under different conditions. The method is reasonable in route, few in side reaction, high in yield, simple to operate, mild in reaction condition, low in equipment requirement and suitable for large-scale industrial production.
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Paragraph 0055-0059; 0062-0064

(2021/12/07)

An Enantioconvergent Benzylic Hydroxylation Using a Chiral Aryl Iodide in a Dual Activation Mode
The application of a triazole-substituted chiral iodoarene in a direct enantioselective hydroxylation of alkyl arenes is reported. This method allows the rapid synthesis of chiral benzyl alcohols in high yields and stereocontrol, despite its nontemplated nature. In a cascade activation consisting of an initial irradiation-induced radical C-H-bromination and a consecutive enantioconvergent hydroxylation, the iodoarene catalyst has a dual role. It initiates the radical bromination in its oxidized state through an in-situ-formed bromoiodane and in the second, Cu-catalyzed step, it acts as a chiral ligand. This work demonstrates the ability of a chiral aryl iodide catalyst acting both as an oxidant and as a chiral ligand in a highly enantioselective C-H-activating transformation. Furthermore, this concept presents an enantioconvergent hydroxylation with high selectivity using a synthetic catalyst.
Abazid, Ayham H.,Clamor, Nils,Nachtsheim, Boris J.
p. 8042 - 8048
(2020/09/21)

Green synthesis of chiral aromatic alcohols with Lactobacillus kefiri P2 as a novel biocatalyst
Biocatalytic reduction is a very important field of research in synthetic organic chemistry. Herein, three different Lactic Acid Bacteria (LAB) strains were evaluated for their bioreduction potential using acetophenone as a model substrate. Among these strains, Lactobacillus kefiri P2 strain was determined as the best asymmetric reduction biocatalyst. Reaction optimization parameters such as reaction time, temperature, agitation speed and pH were systematically optimized using Lactobacillus kefiri P2 strain and model substrate acetophenone. Under these optimized reaction conditions, secondary chiral alcohols were obtained by bioreduction of various prochiral ketones with results up to 99% enantiomeric excess. In addition, the steric and electronic effects of substituents on enantioselectivity and conversion were evaluated. It has been shown that Lactobacillus kefiri P2 biocatalyst was an effective catalyst for asymmetric reduction. This method provides an environmentally friendly method for the synthesis of optically pure alcohols and an alternative approach to chemical catalysts.
Bayda?, Yasemin,Dertli, Enes,?ahin, Engin
p. 1035 - 1045
(2020/03/03)

Optimisation, scope and advantages of the synthesis of chiral phenylethanols using whole seeds of Bauhinia variegata L. (Fabaceae) as a new and stereoselective bio-reducer of carbonyl compounds
With the aim of finding new methods for environmentally friendly synthesis of chiral phenylethanols, a screening was carried out to identify seeds that could be used as a biocatalyst capable of reducing stereoselectively prochiral ketones. As a result, seeds of Bauhinia variegata L. (Fabaceae) were identified as being an efficient and stereoselective biological reducer of acetophenone to produce (S)-1-phenylethanol (conversion of 98% and 99 e.e.%). Then, to optimise the reductive process, the effects of some variables such as temperature, load of substrate, pH, co-solvent, and reuse and storability of the seeds as a function of time were established. Utilising the optimal reaction conditions, nineteen substituted acetophenones were reduced to their corresponding chiral alcohols with a conversion ranging from 30% to 98% and enantiomeric excess of between 65% and >99%, and in addition, useful key intermediates were also obtained by the synthesis of drugs. The scope and advantages of this new biocatalytic synthetic method are also discussed.Research highlights A screening was carried out to identify seeds that could be used as a biocatalyst Seeds of Bauhinia variegata have been identified as an efficient biocatalyst to reduce carbonyl compounds. Acetophenone and substituted acetophenones were reduced with high stereoselectivity. Some key intermediates were synthetised using this methodology. Seeds can be stored for twenty-four months without loss of activity.
Aimar, Mario L.,Bordón, Daniela L.,Cantero, Juan J.,Decarlini, María F.,Demmel, Gabriela I.,Rossi, Laura I.,Ruiz, Gustavo M.,Vázquez, Ana M.
p. 1 - 15
(2020/07/14)

Enantioselective Hydroboration of Ketones Catalyzed by Rare-Earth Metal Complexes Containing Trost Ligands
Four chiral dinuclear rare-earth metal complexes [REL1]2 (RE = Y(1), Eu(2), Nd(3), La (4)) stabilized by Trost proligand H3L1 (H3L1 = (S,S)-2,6-bis[2-(hydroxydiphenylmethyl)pyrrolidin-1-ylmethyl]-4-methylphenol) were first prepared, and all were characterized by X-ray diffraction. Complex 4 was employed as the catalyst for enantioselective hydroboration reaction of substituted ketones, and the corresponding secondary alcohols with excellent yields and high ee values were obtained using reductant HBpin. The same result was also achieved using the combination of lanthanium amides La[N(SiMe3)2]3 with Trost proligand H3L1 in a 1:1 molar ratio. The experimental findings and DFT calculation revealed the possible mechanism of the enantioselective hydroboration reaction and defined the origin of the enantioselectivity in the current system.
Lu, Chengrong,Sun, Yuli,Xue, Mingqiang,Zhao, Bei
p. 10504 - 10513
(2020/09/23)

Synthesis of thioethers, arenes and arylated benzoxazoles by transformation of the C(aryl)-C bond of aryl alcohols
Transformation of aryl alcohols into high-value functionalized aromatic compounds by selective cleavage and functionalization of the C(aryl)-C(OH) bond is of crucial importance, but very challenging by far. Herein, for the first time, we report a novel and versatile strategy for activation and functionalization of C(aryl)-C(OH) bonds by the cooperation of oxygenation and decarboxylative functionalization. A diverse range of aryl alcohol substrates were employed as arylation reagents via the cleavage of C(aryl)-C(OH) bonds and effectively converted into corresponding thioether, arene, and arylated benzoxazole products in excellent yields, in a Cu based catalytic system using O2 as the oxidant. This study offers a new way for aryl alcohol conversion and potentially offers a new opportunity to produce high-value functionalized aromatics from renewable feedstocks such as lignin which features abundant C(aryl)-C(OH) bonds in its linkages.
Chen, Bingfeng,Han, Buxing,Liu, Mingyang,Meng, Qinglei,Song, Jinliang,Zhang, Pei,Zhang, Zhanrong
p. 7634 - 7640
(2020/08/14)

Highly Enantioselective Transfer Hydrogenation of Prochiral Ketones Using Ru(II)-Chitosan Catalyst in Aqueous Media
Unprecedentedly high enantioselectivities are obtained in the transfer hydrogenation of prochiral ketones catalyzed by a Ru complex formed in situ with chitosan chiral ligand. This biocompatible, biodegradable chiral polymer obtained from the natural chitin afforded good, up to 86 % enantioselectivities, in the aqueous-phase transfer hydrogenation of acetophenone derivatives using HCOONa as hydrogen donor. Cyclic ketones were transformed in even higher, over 90 %, enantioselectivities, whereas further increase, up to 97 %, was obtained in the transfer hydrogenations of heterocyclic ketones. The chiral catalyst precursor prepared ex situ was examined by scanning electron microscopy, FT-mid- and -far-IR spectroscopy. The structure of the in situ formed catalyst was investigated by 1H NMR spectroscopy and using various chitosan derivatives. It was shown that a Ru pre-catalyst is formed by coordination of the biopolymer to the metal by amino groups. This precursor is transformed in water insoluble Ru-hydride complex following hydrogen donor addition. The practical value of the developed method was verified by preparing over twenty chiral alcohols in good yields and optical purities. The catalyst was applied for obtaining optically pure chiral alcohols at gram scale following a single crystallization.
Sz?ll?si, Gy?rgy,Kolcsár, Vanessza Judit
p. 820 - 830
(2018/12/13)

Chirality-Economy Catalysis: Asymmetric Transfer Hydrogenation of Ketones by Ru-Catalysts of Minimal Stereogenicity
This manuscript describes the design and synthesis of Ru catalysts that feature only a single stereogenic element, yet this minimal chirality resource is demonstrated to be competent for effecting high levels of stereoinduction in the asymmetric transfer hydrogenation over a broad range of ketone substrates, including those that are not accommodated by known catalyst systems. The single stereogenic center of the (1-pyridine-2-yl)methanamine) is the only point-chirality in the catalysts, which simplifies this catalyst system relative to existing literature protocols.
Chen, Fumin,He, Dongxu,Chen, Li,Chang, Xiaoyong,Wang, David Zhigang,Xu, Chen,Xing, Xiangyou
p. 5562 - 5566
(2019/06/05)

Chemoselective Derivatization of Folded Synthetic Insulin Variants with Potassium Acyltrifluoroborates (KATs)
Synthetic folded insulin variants containing an ornithine-hydroxylamine residue are readily modified in aqueous buffers by amide-forming ligations with potassium acyltrifluoroborates (KATs). The synthetic insulin analogs were prepared by Fmoc-SPPS, α-keto
Boross, Gábor N.,Schauenburg, Dominik,Bode, Jeffrey W.
(2019/01/24)

Production of enantiomerically enriched chiral carbinols using Weissella paramesenteroides as a novel whole cell biocatalyst
In this study, four bacterial strains were tested for their ability to reduce acetophenones to its corresponding alcohol. Among these strains Weissella paramesenteroides N7 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for W. paramesenteroides N7 that resulted in high enantioselectivity and conversion rates for the bioreduction. The scale-up asymmetric reduction of 1-(4-methoxyphenyl) propan-1-one (1r) by W. paramesenteroides N7 gave (R)-1-(4-methoxyphenyl) propan-1-ol (2r) with 94% yield and >99% enantiomeric excess. This is the first report showing the synthesis of (R)-1-(4-methoxyphenyl) propan-1-ol (2r) in enantiopure form using a biocatalyst on a gram scale. The whole cell catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that W. paramesenteroides N7 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest as a promising and alternative green approach.
Tozlu, Caner,?ahin, Engin,Serencam, Hüseyin,Dertli, Enes
p. 388 - 398
(2019/02/14)

Enantiodiscrimination by matrix-assisted DOSY NMR
High-resolution NMR is an essential technique for structure determination; however, stereochemistry assignment is still an obstacle. Several methods are known to overcome this limitation but usually at high costs or using derivatizations. Here we describe the use of different solvating agents to virtually discriminate the enantiomers of 15 analytes using 1H and 19F-{1H} DOSY NMR.
Salome, Kahlil Schwanka,Tormena, Claúdio Francisco
supporting information
p. 8611 - 8614
(2019/07/25)

Selective Aerobic Oxidation of 4-Ethylnitrobenzene to 4-Nitroacetophenone Promoted by Metalloporphyrins
A solvent-free and environment-friendly process for the oxidation of 4-ethylnitrobenzene to 4-nitroacetophenone promoted by metalloporphyrins was developed in a pressure reactor using O2 as a clean oxidant. The activities and reaction selectivities of the metalloporphyrins could be significantly affected by their central metal ions as well as the nature and position of the substituted groups, which were systematically investigated by employing more than 60 metalloporphyrins. Generally, the Fe(III)- and Mn(II)-porphyrins exhibited high activities. Moreover, metalloporphyrins with electron-withdrawing substituents on the para-positions of the phenyl rings showed activities in the order T(p-Br)PPM T(m-Cl)PPM > T(p-Cl)PPM and T(o-OMe)PPM T(m-OMe)PPM T(p-OMe)PPM were observed. Furthermore, selectivities over 90.0% and a TON of 5370 could be achieved for the desired ketone. Especially, the T(p-Cl)PPMn demonstrated a selectivity of up to 93.6% and a conversion of 51.9% with only 3.3% acid and no alcohol observed, and the selectivity was nearly the same for a large-scale experiment (100 g).
Yang, Yuning,Li, Guijie,Mao, Xinbiao,She, Yuanbin
supporting information
p. 1078 - 1086
(2019/03/26)

Proteins as Macromolecular Ligands for Metal-Catalysed Asymmetric Transfer Hydrogenation of Ketones in Aqueous Medium
Biohybrid catalysts resulting from the dative anchoring of half-sandwich organometallic complexes [M(arene)(H2O)x(Cl)y]n+ (M = RuII, arene = η6-benzene, p-cymene or mesitylene; M = IrIII, RhIII, arene = η5-Cp*; x = 1–3, y = 0–2, n = 0–2) to bovine beta-lactoglobulin (βLG) or hen egg white lysozyme showed unprecedented behaviour. These constructs were shown to catalyse the asymmetric transfer hydrogenation of aryl ketones in water with sodium formate as hydrogen donor at a much faster rate than the complexes alone. Full conversion of the benchmark substrate 2,2,2-trifluoroacetophenone was reached with an ee of 86 % for the most selective biohybrid. Surprisingly, even the crude biohybrid gave a good ee despite the presence of non-protein-bound metal species in the reaction medium. Other aryl ketones were reduced in the same way, and the highest ee was obtained for ortho-substituted acetophenone derivatives. Furthermore, treatment of βLG with dimethyl pyrocarbonate resulted in a noticeable decrease of the activity and selectivity of the biohybrid, indicating that the sole accessible histidine residue (His146) was probably involved in the coordination and activation of Ru(benzene). This work underscores that protein scaffolds are efficient chiral ligands for asymmetric catalysis. The use of sodium formate instead of dihydrogen makes this approach safe, inexpensive and environmentally friendly.
de Jesús Cázares-Marinero, José,Przybylski, Cédric,Salmain, Michèle
p. 1383 - 1393
(2018/04/06)

Synthesis of Enantiomerically Enriched Drug Precursors by Lactobacillus paracasei BD87E6 as a Biocatalyst
Global sales of single enantiomeric drug products are growing at an alarming rate every year. A total of 7 bacterial strains were screened for their ability to reduce acetophenones to its corresponding alcohol. Among these strains Lactobacillus paracasei BD87E6 was found to be the most successful biocatalyst to reduce the ketones to the corresponding alcohols. The reaction conditions were systematically optimized for the reducing agent Lactobacillus paracasei BD87E6, which showed high enantioselectivity and conversion for the bioreduction. The preparative scale asymmetric reduction of 3-methoxyacetophenone (1h) by Lactobacillus paracasei BD87E6 gave (R)-1-(3-methoxyphenyl)ethanol (2h) with 92% yield and 99% enantiomeric excess. Compound 2h could be used for the synthesis of (S)-rivastigmine which has a great potential for the treatment of Alzheimer's disease. This study demonstrates that Lactobacillus paracasei BD87E6 can be used as a biocatalyst to obtain chiral carbinol with excellent yield and selectivity. The whole cell catalyzed the reductions of ketone substrates on the preparative scale, demonstrating that Lactobacillus paracasei BD87E6 would be a valuable biocatalyst for the preparation of chiral aromatic alcohols of pharmaceutical interest.
?ksüz, Selda,?ahin, Engin,Dertli, Enes
(2018/05/30)

A comparative study on asymmetric reduction of ketones using the growing and resting cells of marine-derived fungi
Whole-cell biocatalysts offer a highly enantioselective, minimally polluting route to optically active alcohols. Currently, most of the whole-cell catalytic performance involves resting cells rather than growing cell biotransformation, which is one-step process that benefits from the simultaneous growth and biotransformation, eliminating the need for catalysts preparation. In this paper, asymmetric reduction of 14 aromatic ketones to the corresponding enantiomerically pure alcohols was successfully conducted using the growing and resting cells of marine-derived fungi under optimized conditions. Good yields and excellent enantioselectivities were achieved with both methods. Although substrate inhibition might be a limiting factor for growing cell biotransformation, the selected strain can still completely convert 10-mM substrates into the desired products. The resting cell biotransformation showed a capacity to be recycled nine times without a significant decrease in the activity. This is the first study to perform asymmetric reduction of ketones by one-step growing cell biotransformation.
Liu, Hui,Chen, Bi-Shuang,Ribeiro de Souza, Fayene Zeferino,Liu, Lan
(2018/02/28)

Method for synthesizing alpha-nitrophenylethanol
The invention discloses a method for synthesizing alpha-nitrophenylethanol. The alpha-nitrophenylethanol is mainly prepared from dichloroethane, phenylethyl acetate, concentrated nitric acid, methanol, hydrochloric acid, CoCl2, sodium citrate, NaBH4, H2Pt
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(2019/01/14)

Release of Terminal Alkynes via Tandem Photodeprotection and Decarboxylation of o -Nitrobenzyl Arylpropiolates in a Flow Microchannel Reactor
Photocleavable protecting groups (PPGs) offer a complementary protection paradigm compared to traditional protection groups. Herein, an o-nitrobenzyl (NB) PPG was employed to protect a variety of arylpropiolic acids. Upon a cascade of light-triggered photodeprotection in a microchannel reactor (residence times of 100-500 s), followed by Cu-catalyzed decarboxylation at 60 °C, the NB-protected arylpropiolic acid afforded a terminal alkyne. This terminal alkyne was further reacted in situ with an azide via click chemistry to yield a 1,2,3-triazole in a one-pot reaction. Furthermore, the effect of different substituents (methyl, vinyl, allyl, and phenyl) at the benzylic position on the rate of photodeprotection was studied. The quantum yields of photolysis for the benzylic-substituted esters were determined to be as high as 0.45 compared to the unsubstituted ester with a 0.08 quantum yield of photolysis.
Tebikachew, Behabitu Ergette,B?rjesson, Karl,Kann, Nina,Moth-Poulsen, Kasper
p. 1178 - 1185
(2018/04/23)

Magnetically Recyclable Metal–Organic Framework@Fe3O4 Composite-Catalyzed Facile Reduction of Nitroarene Compounds in Aqueous Medium
A kind of Metal–organic framework (MOF) composite namely Cu-BTC@Fe3O4 (BTC?=?1,3,5-benzenetricarboxylate) was prepared and showed good catalytic activity toward the reduction of nitroarenes. This reaction proceeded smoothly under mild reaction conditions in aqueous medium using sodium borohydride as the reduction agent, affording the corresponding anilines in good to excellent yields. In addition, the catalyst could be easily recovered with an external permanent magnet and be reused for successive six runs with slight decrease in its activity.
Yang, Sen,Zhang, Zhi-Hui,Chen, Qun,He, Ming-Yang,Wang, Liang
(2017/11/09)

Studies on Aculeines: Synthetic Strategy to the Fully Protected Protoaculeine B, the N-Terminal Amino Acid of Aculeine B
A synthetic strategy for accessing protoaculeine B (1), the N-terminal amino acid of the highly modified peptide toxin aculeine, was developed via the synthesis of the fully protected natural homologue of 1 with a 12-mer poly(propanediamine). The synthesis of mono(propanediamine) analog 2, as well as core amino acid 3, was demonstrated by this strategy. New amino acid 3 induced convulsions in mice; however, compound 2 showed no such activity.
Shiozaki, Hiroki,Miyahara, Masayoshi,Otsuka, Kazunori,Miyako, Kei,Honda, Akito,Takasaki, Yuichi,Takamizawa, Satoshi,Tukada, Hideyuki,Ishikawa, Yuichi,Sakai, Ryuichi,Oikawa, Masato
supporting information
p. 3403 - 3407
(2018/06/11)

COMPOUND AND PHOTO-BASE GENERATOR COMPOSED OF THE COMPOUND
PROBLEM TO BE SOLVED: To provide a novel compound that functions as a photo-base generator that allows the curing reaction of an epoxy resin to quickly proceed. SOLUTION: The present invention provides a compound represented by formula (I) (R1-R6 independently represent H, a C1-C5 hydrocarbon group or a C1-C5 hydrocarbon oxy group ; R7 is a C1-C6 hydrocarbon group or C6-C15 aromatic ring; R8-R9 independently represent H or a C1-C15 hydrocarbon group; at least one of R8 and R9 represents the hydrocarbon group, and R8 and R9 may together form a ring structure). SELECTED DRAWING: None COPYRIGHT: (C)2018,JPOandINPIT
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(2018/06/01)

Photo-responsive nanoparticles for β-lapachone delivery in vitro
Drug efficiency delivery and release to target site play an important role in the treatment of cancer. To achieve these goals, developing drug delivery systems is the key step. The common materials used for drug delivery like liposomes, micelles, dendrimers cannot control the delivery and releasing by spatial and temporal. In this paper, we design a photoresponsive drug delivery system to reduce the side effects of traditional chemotherapy on normal cells and improve therapeutic efficacy in treating cancers. We synthesized two kinds of photo-responsive polymers using two different monomers containing two photoresponsive groups. The two monomers were crosslinked by poly (ethylene glycol) dimethacrylate to form polymers and then encapsulated β-lapachone into the nanoparticles, after UV irradiation, the particle will degrade and release the drug. This method may provide new strategies for the photoresponsive nanomaterials.
Li, Huibo,Chen, Changmai,An, Qin,Huo, Guoyan,Run, Mingtao
p. 1347 - 1349
(2017/12/06)

Aminotriazole Mn(I) Complexes as Effective Catalysts for Transfer Hydrogenation of Ketones
A catalytic system based on complexes comprising abundant and cheap manganese together with readily available aminotriazole ligands is reported. The new Mn(I) complexes are catalytically competent in transfer hydrogenation of ketones with 2-propanol as hydrogen source. The reaction proceeds under mild conditions at 80 °C for 20 h with 3 % of catalyst loading using either KOtBu or NaOH as base. Good to excellent yields were obtained for a wide substrate scope with broad functional group tolerance. The obtained results by varying the substitution pattern of the ligand are consistent with an out-sphere mechanism for the H-transfer.
Martínez-Ferraté, Oriol,Werlé, Christophe,Franciò, Giancarlo,Leitner, Walter
p. 4514 - 4518
(2018/10/20)

Metal-Free Aerobic Oxidation of Nitro-Substituted Alkylarenes to Carboxylic Acids or Benzyl Alcohols Promoted by NaOH
Efficient and selective aerobic oxidation of nitro-substituted alkylarenes to functional compounds is a fundamental process that remains a challenge. Here, we report a metal-free, efficient, and practical approach for the direct and selective aerobic oxidation of nitro-substituted alkylarenes to carboxylic acids or benzyl alcohols. This sustainable system uses O2 as clean oxidant in a cheap and green NaOH/EtOH mixture. The position and type of substituent critically affect the products. In addition, this sustainable protocol enabled gram-scale preparation of carboxylic acid and benzyl alcohol derivatives with high chemoselectivities. Finally, the reactions can be conducted in a pressure reactor, which can conserve oxygen and prevent solvent loss. The approach was conducive to environmental protection and potential industrial application.
Fang, Kun,Li, Guijie,She, Yuanbin
p. 8092 - 8103
(2018/06/25)

Highly Enantioselective Production of Chiral Secondary Alcohols Using Lactobacillus paracasei BD101 as a New Whole Cell Biocatalyst and Evaluation of Their Antimicrobial Effects
Chiral secondary alcohols are valuable intermediates for many important enantiopure pharmaceuticals and biologically active molecules. In this work, we studied asymmetric reduction of aromatic ketones to produce the corresponding chiral secondary alcohols using lactic acid bacteria (LAB) as new biocatalysts. Seven LAB strains were screened for their ability to reduce acetophenones to their corresponding alcohols. Among these strains, Lactobacillus paracasei BD101 was found to be the most successful at reducing the ketones to the corresponding alcohols. The reaction conditions were further systematically optimized for this strain and high enantioselectivity (99%) and very good yields were obtained. These secondary alcohols were further tested for their antimicrobial activities against important pathogens and significant levels of antimicrobial activities were observed although these activities were altered depending on the secondary alcohols as well as their enantiomeric properties. The current methodology demonstrates a promising and alternative green approach for the synthesis of chiral secondary alcohols of biological importance in a cheap, mild, and environmentally useful process.
Y?lmaz, Durmu?han,?ahin, Engin,Dertli, Enes
(2017/10/25)

Debaryomyces hansenii as a new biocatalyst in the asymmetric reduction of substituted acetophenones
Chiral secondary alcohols are convenient mediator for the synthesis of biologically active compounds and natural products. In this study fifteen yeast strains belonging to three food originated yeast species Debaryomyces hansenii, Saccharomyces cerevisiae and Hanseniaspora guilliermondii were tested for their capability for the asymmetric reduction of acetophenone to 1-phenylethanol as biocatalyst microorganisms. Of these strains, Debaryomyces hansenii P1 strain showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to the corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high conversion rates. This is the first report on the enantioselective reduction of acetophenone by D. hansenii P1 from past?rma, a fermented Turkish meat product. The preparative scale asymmetric bio reduction of 3-methoxy acetophenone 1g by D. hansenii P1 gave (R)-1-(3-methoxyphenyl) ethanol 2g 82% yield, and >99% enantiomeric excess. Compound 2g can be used for the synthesis of (+)-NPS-R-568 [3-(2-chlorophenyl)-N-[(1R)-1-(3-methoxyphenly) ethyl] propan-1-amine] which have a great potential for the treatment of primary and secondary hyper-parathyroidism. In addition, D. hansenii P1 successfully reduced acetophenone derivatives. This study showed that this yeast can be used industrially to produce enantiomerically pure chiral secondary alcohols, which can be easily converted to different functional groups.
?ahin, Engin
p. 363 - 371
(2017/09/13)

Highly Enantioselective Production of Chiral Secondary Alcohols with Candida zeylanoides as a New Whole Cell Biocatalyst
The increasing demand for biocatalysts in synthesizing enantiomerically pure chiral alcohols results from the outstanding characteristics of biocatalysts in reaction, economic, and ecological issues. Herein, fifteen yeast strains belonging to three food originated yeast species Candida zeylanoides, Pichia fermentans, and Saccharomyces uvarum were tested for their capability for asymmetric reduction of acetophenone to 1-phenylethanol as biocatalysts. Of these strains, C.?zeylanoides P1 showed an effective asymmetric reduction ability. Under optimized conditions, substituted acetophenones were converted to corresponding optically active secondary alcohols in up to 99% enantiomeric excess and at high yields. The preparative scale asymmetric bioreduction of 4-nitroacetophenone (1m) by C.?zeylanoides P1 gave (S)-1-(4-nitrophenyl)ethanol (2m) with 89% yield and >?99% enantiomeric excess. Compound 2m has been obtained in an enantiomerically pure and inexpensive form. Additionally, these results indicate that C.?zeylanoides P1 is a promising biocatalyst for the synthesis of chiral alcohols in industry.
?ahin, Engin,Dertli, Enes
(2017/09/18)

Photoprotected Peptide α-Ketoacids and Hydroxylamines for Iterative and One-Pot KAHA Ligations: Synthesis of NEDD8
The convergent synthesis of proteins by multiple ligations requires segments protected at the N- and/or C-terminus with masking groups that are orthogonal to the acid- and base-labile protecting groups used in Fmoc-SPPS. They must be stable to solid-phase
Thuaud, Frédéric,Rohrbacher, Florian,Zwicky, André,Bode, Jeffrey W.
p. 868 - 894
(2016/11/11)

MASSIVE PARALLEL METHOD FOR DECODING DNA AND RNA
This invention provides methods for attaching a nucleic acid to a solid surface and for sequencing nucleic acid by detecting the identity of each nucleotide analogue after the nucleotide analogue is incorporated into a growing strand of DNA in a polymerase reaction. The invention also provides nucleotide analogues which comprise unique labels attached to the nucleotide analogue through a cleavable linker, and a cleavable chemical group to cap the —OH group at the 3′-position of the deoxyribose.
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Paragraph 0054; 0158

(2016/12/16)

Efficient and recyclable Ru(II) arene thioamide catalysts for transfer hydrogenation of ketones: Influence of substituent on catalytic outcome
Six cationic ruthenium(II) arene thioamide complexes with the general molecular formula [Ru(η6-p-cymene)(PPh3)(L)]+ [where, L = pyridine-2-thioamide and its derivatives] have been successfully synthesized from the reaction of [Ru(η6-p-cymene)Cl2]2 with chelating thioamide ligands and PPh3 in methanol in 1:2 M ratio respectively. All the complexes were isolated as their BPh4?salts and were fully characterized by analytical and spectral (FT-IR, UV-Vis and1H-NMR) methods. The solid-state structure of one of the complexes, [Ru(η6-p-cymene)(PPh3)(L4)]BPh4 (4) (L4 = N-(2, 4, 6-Trimethylphenyl)pyridine-2-thiocarboxamide) has been established by X-ray single crystal diffraction which indicates a pseudo-octahedral (piano-stool) coordination geometry is present in the complex. The ruthenium(II) complexes have been examined for the transfer hydrogenation of various aromatic, heterocycle and cyclic ketones. The formation of ruthenium(II) hydride is confirmed by 1H- NMR and is proposed as the catalytic intermediate in this reaction. Under the optimized conditions, these ruthenium complexes served as excellent catalyst precursors which smoothly reduce the ketones with conversion up to 100%. The influence of other variables on the transfer hydrogenation reaction such as solvent, base, temperature, time, catalyst loading and substrate scope is also reported. Furthermore, the catalyst could be easily recovered and reused at least three times without obvious loss of conversions.
Kanchanadevi, Appukutti,Ramesh, Rengan,Semeril, David
p. 68 - 77
(2018/03/27)

Asymmetric reduction of ketones catalyzed by α,α-diphenyl-(L)-prolinol modified with imidazolium ionic liquid and BH3·SMe2 as a recoverable catalyst
The synthesis of α,α-diphenyl-4-trans-hydroxy-(L)-prolinol modified with imidazolium based ionic liquids was carried out with trans-α,α-diphenyl-4-hydroxy-(L)-prolinol, 5-bromovaleric acid or 1,5-dibromopentane and imidazole. α,α-Diphenyl-4-hydroxy-(L)-prolinol modified with imidazolium ionic liquid was treated with BH3·SMe2 which generate 1,3,2-oxazaborolidine, that acts as a catalyst for asymmetric reduction of prochiral ketones. α,α-Diphenyl-4-hydroxy-(L)-prolinol modified with imidazolium ionic liquids (PF6 anion) with BH3?SMe2 found to be an efficient catalyst (10 mol%) for the reduction of the acetophenone, gave 99% yield and 87-84% ee. The catalytic method has wide applicability for a variety of substrates. 1,3,2-oxazaborolidine containing ether linkage ionic liquid was recovered and reused up to 4 cycles with 99-91% yields and 87-81% ee's.
Chauhan, ManMohan Singh,Singh, Surendra
p. 184 - 189
(2015/02/19)

Nucleotides and nucleosides and methods for their use in DNA sequencing
The present invention relates generally to labeled and unlabled cleavable terminating groups and methods for DNA sequencing and other types of DNA analysis. More particularly, the invention relates in part to nucleotides and nucleosides with chemically cleavable, photocleavable, enzymatically cleavable, or non-photocleavable groups and methods for their use in DNA sequencing and its application in biomedical research.
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Page/Page column 57

(2015/12/18)

Coordinating chiral ionic liquids: Design, synthesis, and application in asymmetric transfer hydrogenation under aqueous conditions
Hydrophilic coordinating chiral ionic liquids with an amino alcohol substructure were developed and efficiently applied to the asymmetric reduction of ketones. Their careful design and adaptability to the desired reaction conditions allow for these chiral ionic liquids to be used as the sole source of chirality in a ruthenium-catalyzed transfer hydrogenation reaction of aromatic ketones. When used in this reaction system, these chiral ionic liquids afforded excellent yields and high enantioselectivities.
Vasiloiu, Maria,Gaertner, Peter,Zirbs, Ronald,Bica, Katharina
p. 2374 - 2381
(2015/04/22)

Fruits of the glossy privet (Ligustrum lucidum-Oleaceae) as biocatalysts for producing chiral aromatic alcohols
The screening of four invasive plant species for use as biocatalysts in the stereoselective reduction of ketones is reported. Our studies revealed that fruits of Ligustrum lucidum can be used for the bioreduction of acetophenone to (S)-1-phenylethanol (94% conversion, >99 enantiomeric excess [ee]%). Using this methodology, 13 substituted (S)-phenylethanols were synthesized with good ee values (>99.9 to 78%) using a technique which is more environmentally friendly than classical reduction of prochiral ketones. The results reveal the fruits of L. lucidum to be promising biocatalysts for the production of key intermediates.
Aimar, Mario L.,BordN, Daniela L.,Formica, Stella M.,Cantero, Juan J.,Vazquez, Ana M.,Velasco, Manuel I.,Rossi, Laura I.
p. 348 - 357
(2015/02/19)

From in vitro to in cellulo: Structure-activity relationship of (2-nitrophenyl)methanol derivatives as inhibitors of PqsD in Pseudomonas aeruginosa
Recent studies have shown that compounds based on a (2-nitrophenyl)methanol scaffold are promising inhibitors of PqsD, a key enzyme of signal molecule biosynthesis in the cell-to-cell communication of Pseudomonas aeruginosa. The most promising molecule displayed anti-biofilm activity and a tight-binding mode of action. Herein, we report on the convenient synthesis and biochemical evaluation of a comprehensive series of (2-nitrophenyl)methanol derivatives. The in vitro potency of these inhibitors against recombinant PqsD as well as the effect of selected compounds on the production of the signal molecules HHQ and PQS in P. aeruginosa were examined. The gathered data allowed the establishment of a structure-activity relationship, which was used to design fluorescent inhibitors, and finally, led to the discovery of (2-nitrophenyl)methanol derivatives with improved in cellulo efficacy providing new perspectives towards the application of PqsD inhibitors as anti-infectives. This journal is the Partner Organisations 2014.
Storz, Michael P.,Allegretta, Giuseppe,Kirsch, Benjamin,Empting, Martin,Hartmann, Rolf W.
supporting information
p. 6094 - 6104
(2014/08/05)

A well-defined monomeric aluminum complex as an efficient and general catalyst in the Meerwein-Ponndorf-Verley reduction
The metal-catalyzed Meerwein-Ponndorf-Verley (MPV) reduction allows for the mild and sustainable reduction of aldehydes and ketones but has not found widespread application in organic synthesis due to the high catalyst loading often required to obtain satisfactory yields of the reduced product. We report here on the synthesis and structure of a sterically extremely overloaded siloxide-supported aluminum isopropoxide capable of catalytically reducing a wide range of aldehydes and ketones (52 examples) in excellent yields under mild conditions and with low catalyst loadings. The unseen activity of the developed catalyst system in MPV reductions is due to its unique monomeric nature and the neutral donor isopropanol weakly coordinating to the aluminum center. The present work implies that monomeric aluminum alkoxide catalysts may be attractive alternatives to transition-metalbased systems for the selective reduction of aldehydes and ketones to primary and secondary alcohols.
McNerney, Brian,Whittlesey, Bruce,Cordes, David B.,Krempner, Clemens
supporting information
p. 14959 - 14964
(2015/01/08)

Kluyveromyces marxianus CBS 6556 growing cells as a new biocatalyst in the asymmetric reduction of substituted acetophenones
The use of microorganism growing cells is a well recognized methodology in biocatalyzed organic reactions. A non-conventional thermotolerant Kluyveromyces marxianus yeast strain was used for the bio-reduction of different arylketones. Differently substituted ketones were converted into the corresponding (S)-alcohols with up to 96% enantiomeric excess under very mild reaction conditions. Kluyveromyces marxianus represents a promising biocatalyst for the production of optically active 1-arylethanols.
Vitale, Paola,D'Introno, Cinzia,Perna, Filippo Maria,Perrone, Maria Grazia,Scilimati, Antonio
p. 389 - 394
(2013/06/26)

Synthesis of chiral secondary β-amino alcohols and their application in the asymmetric reduction of prochiral ketones
Nine chiral secondary β-amino alcohols were synthesized from chiral primary amino alcohols and aromatic aldehydes, and their catalysis for the asymmetric reduction of prochiral ketone was studied with good yields up to 87% ee (enantiometric excess).
Ran, De-Qiang,Shen, Tian-Hua,Zhou, Xiao-Cong,Ma, Chun-An,Song, Qing-Bao
p. 125 - 129
(2013/05/09)

Photoresponsive cross-linked polymeric particles for phototriggered burst release
We synthesized a series of cross-linked photoresponsive polymeric particles with photolabile monomers and cross-linkers through miniemulsion polymerization. These particles are quite stable in dark, while light irradiation caused the breakage of particles and the efficient release of encapsulated contents up to 95% based on Nile red fluorescence. Photoswitches of particle systems were confirmed by fluorescence spectroscopy, SEM and colorimetry. Particle uptake and triggered release in RAW264.7 cells were confirmed by fluorescein diacetate loaded particles.
Wang, Zhen,Yu, Lili,Lv, Cong,Wang, Peng,Chen, Yedong,Tang, Xinjing
p. 552 - 559
(2013/06/26)

Synthesis of light-induced expandable photoresponsive polymeric nanoparticles for triggered release
High stability of drug-delivery nanocarriers during blood circulation is critical for effective drug delivery and low systematic toxicity, although destabilization of these nanocarriers is required for efficient release when they reach target sites. To develop efficient polymeric nanocarriers, we intended to synthesize and characterize a group of cross-linked, light-induced, expandable, polymeric nanoparticles through miniemulsion polymerization. These synthesized nanoparticles were stable in aqueous solutions, although light irradiation led to particle uncaging and further particle expansion up to 315-fold in volume. This resulted in the efficient release of the encapsulated contents in aqueous solutions and three cell lines (HeLa, RAW264.7, and MCF-7). Selective triggered release was also successfully achieved with spatial resolution in cell monolayers. In addition, curcumin encapsulation and photoregulation of its release were realized. Further cell viability of encapsulated curcumin was successfully achieved with light activation. Open the cage: A series of cross-linked photolabile polymeric nanoparticles are described. Light irradiation leads to the particle swelling 315-fold in volume and the efficient release of the encapsulated contents in both aqueous solutions and cells. Selective triggered release on a cell monolayer is achieved. Curcumin is efficiently encapsulated in particles and photoregulation of its release and cell viability is also successfully achieved. Copyright
Wang, Zhen,Wang, Peng,Tang, Xinjing
p. 1273 - 1281
(2013/11/06)

Asymmetric reduction of acetophenone derivatives by Lens culinaris
The enzymatic reduction of acetophenone derivatives has been evaluated using whole cells from the edible plant lentil (Lens culinaris) as biocatalyst to afford chiral (R) and (S)-alcohols in enantiomeric excess 68-99%. Acetophenone was selected as the model substrate for enantioselective bioreduction. The reaction was performed under a range of conditions in order to optimize the bioreduction procedure with respect to reaction time, media and optimal mass of lentil. With substituted (fluorine, chlorine, bromine, methyl, hydroxyl, methoxy, amino and nitro groups) acetophenones, electronic and steric influences on the course of the reaction were observed.
Ferreira, Daniele Alves,Da Costa Assun??o, Jo?o Carlos,De Lemos, Telma Leda Gomes,Monte, Francisco José Queiroz
p. 469 - 475
(2013/02/23)

Varying the ratio of formic acid to triethylamine impacts on asymmetric transfer hydrogenation of ketones
Asymmetric transfer hydrogenation (ATH) is frequently carried out in the azeotropic mixture of formic acid (F) and triethylamine (T), where the F/T molar ratio is 2.5. This study shows that the F/T ratio affects both the reduction rate and enantioselectivity, with the optimum ratio being 0.2 in the ATH of ketones with the Ru-TsDPEN catalyst. Under such conditions, a range of substrates have been reduced, affording high yields and good to excellent enantioselectivities. In comparison with the common azeotropic F-T system, the reduction is faster. This protocol improves both the classic azeotropic and the aqueous-formate system when using water-insoluble ketones.
Zhou, Xiaowei,Wu, Xiaofeng,Yang, Bolun,Xiao, Jianliang
experimental part
p. 133 - 140
(2012/05/20)

Highly active mesoporous chromium silicate catalysts in side-chain oxidation of alkylaromatics
We approach a green method in the production of alkylaromatic ketones over hexagonally ordered mesoporous CrSBA-15 catalysts, which were used, in green routes, in the liquid-phase oxidation of alkylaromatics. A promising chemical treatment method was used with ammonium acetate solution to remove the toxic nature of non-framework chromium oxides deposited on the surface of calcined CrSBA-15(8), and the obtained green mesoporous CrSBA-15(8) catalyst was used to find its catalytic activity while the recyclability of mesoporous CrSBA-15 catalysts was also studied. Particularly, the mesoporous CrSBA-15 catalysts synthesized with a variety of chromium contents were extensively used in the production of acetophenone (APO) with various reaction parameters. On the basis of all catalytic results, the mesoporous CrSBA-15(8) catalyst produced a higher selectivity of alkylaromatic ketones (76-100%) as compared to other CrSBA-15 catalysts and was found to be a highly active, recyclable and promising heterogeneous catalyst for selective synthesis of alkylaromatic ketones. The Royal Society of Chemistry 2012.
Selvaraj,Park,Kim,Kawi,Ha
p. 14204 - 14210
(2013/01/15)

Photocaging strategy for functionalisation of oligonucleotides and its applications for oligonucleotide labelling and cyclisation
We have used a photocaging strategy to develop novel phosphoramidites and expand the repertoire of protecting groups for modification of oligonucleotides by solid-phase synthesis. We synthesised five photolabile phosphoramidites and four new photolabile c
Su, Meng,Wang, Jie,Tang, Xinjing
experimental part
p. 9628 - 9637
(2012/09/21)