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Chengxia Miao, Xiao-Xi Li, Yong-Min Lee, Chungu Xia, Yong Wang, Wonwoo Nam, Wei Sun
The highly efficient catalytic oxidation and oxidative kinetic resolution (OKR) of secondary alcohols has been achieved using a synthetic manganese catalyst with low loading and hydrogen peroxide as an environmentally benign oxidant in the presence of a small amount of sulfuric acid as an additive. The product yields were high (up to 93%) for alcohol oxidation and the enantioselectivity was excellent (>90% ee) for the OKR of secondary alcohols. Mechanistic studies revealed that alcohol oxidation occurs via hydrogen atom (H-atom) abstraction from an α-CH bond of the alcohol substrate and a two-electron process by an electrophilic Mn-oxo species...
November 1, 2017: Chemical Science
Chandra S Chirumamilla, Ajay Palagani, Balu Kamaraj, Ken Declerck, Marinus W C Verbeek, Ryabtsova Oksana, Karolien De Bosscher, Nadia Bougarne, Bart Ruttens, Kris Gevaert, René Houtman, Winnok H De Vos, Jurgen Joossens, Pieter Van Der Veken, Koen Augustyns, Xaveer Van Ostade, Annemie Bogaerts, Hans De Winter, Wim Vanden Berghe
Synthetic glucocorticoids (GC) are the mainstay therapy for treatment of acute and chronic inflammatory disorders. Due to the high adverse effects associated with long-term use, GC pharmacology has focused since the nineties on more selective GC ligand-binding strategies, classified as selective glucocorticoid receptor (GR) agonists (SEGRAs) or selective glucocorticoid receptor modulators (SEGRMs). In the current study, GSK866 analogs with electrophilic covalent-binding warheads were developed with potential SEGRA properties to improve their clinical safety profile for long-lasting topical skin disease applications...
2017: Frontiers in Immunology
Nemanja Đorđević, Rakesh Ganguly, Milena Petković, Dragoslav Vidović
In this work, strategic enhancement of electrophilicity of phosphenium cations for the purpose of small-molecule activation was described. Our synthetic methodology for generation of novel two-coordinate phosphorus(III)-based compounds [{C6H4(MeN)2C}2C·PR](2+) ([2a](2+), R = N(i)Pr2; [2b](2+), R = Ph) was based on the exceptional electron-donating properties of the carbodicarbene ligand (CDC). The effects of P-centered substituent exchange and increase in the overall positive charge on small substrate activation were comparatively determined by incorporating the bis(amino)phosphenium ion [((i)Pr2N)2P](+) ([1](+)) in this study...
November 21, 2017: Inorganic Chemistry
Yi-Hung Chen, Simon Graßl, Paul Knochel
Aryl- and heteroaryl-zinc pivalates are aminated with O-benzoylhydroxylamines at 25 °C within 2-4 h in the presence of 2-5% CoCl2*2LiCl furnishing the corresponding tertiary arylated or heteroarylated amines in good yields. This electrophilic amination provides also an access to diarylamines and aryl(heteroaryl)amines. A new tuberculosis drug candidate (Q203) was prepared in 6 steps and 56% overall yield using this cobalt-catalyzed amination as the key step.
November 21, 2017: Angewandte Chemie
Wenjuan Liu, Hao Min, Xiaoming Zhu, Guobo Deng, Yun Liang
An efficient and practical procedure for the synthesis of 2-benzyl- and 2-benzylidene-substituted benzo[b]thiazinones from easily available 2-iodophenylcinnamamides and potassium sulfide has been developed. In the presence of DBU, the reaction proceeds via electrophilic addition, followed by dehydrogenation and reduction to give 2-benzyl benzo[b]thiazinones. Furthermore, 2-benzylidenebenzo[b]thiazinones were obtained in moderate to good yields without the addition of DBU.
November 21, 2017: Organic & Biomolecular Chemistry
Nikolette L McCombs, Tatyana Smirnova, Reza A Ghiladi
The use of oxidoreductases as biocatalysts in the syntheses of functionalized, monomeric pyrroles has been a challenge owing to, among a number of factors, undesired polypyrrole formation. Here, we have investigated the ability of dehaloperoxidase (DHP), the coelomic hemoglobin from the terebellid polychaete Amphitrite ornata, to catalyze the H2O2-dependent oxidation of pyrroles as a new class of substrate for this enzyme. Substrate oxidation was observed for all compounds employed (pyrrole, N-methylpyrrole, 2-methylpyrrole, 3-methylpyrrole and 2,5-dimethylpyrrole) under both aerobic and anaerobic conditions...
2017: Catalysis Science & Technology
Chen-Shan Chen Woodcock, Yi Huang, Steven R Woodcock, Sonia R Salvatore, Bhupinder Singh, Franca Golin-Bisello, Nancy E Davidson, Carola Neumann, Bruce A Freeman, Stacy G Wendell
Triple negative breast cancer (TNBC) comprises ~20% of all breast cancers and is the most aggressive mammary cancer subtype. Devoid of the estrogen and progesterone receptors, along with the receptor tyrosine kinase ERB2 (HER2) that define most mammary cancers, there are no targeted therapies for patients with TNBC. This, combined with a high metastatic rate and a lower 5-year survival rate than for other breast cancer phenotypes, means there is significant unmet need for new therapeutic strategies. Herein, the anti-neoplastic effects of the electrophilic fatty acid nitroalkene derivative, 10-nitro-octadec-9-enoic acid (nitro-oleic acid, NO2-OA), were investigated in multiple preclinical models of TNBC...
November 20, 2017: Journal of Biological Chemistry
David Bulfield, Stefan M Huber
Polyfluorinated biphenyls are interesting and promising substrates for many different applications. Unfortunately, all current methods for the syntheses of these compounds only work for a hand full of molecules or only in very special cases. Thus, many of these compounds are still inaccessible to date. Here we report a general strategy for the synthesis of a wide range of highly fluorinated biphenyls. In our studies we investigated crucial parameters such as different phos-phine ligands and the influence of various nucleophiles and electrophiles with different degrees of fluorination...
November 21, 2017: Journal of Organic Chemistry
Olga Gorelenkova Miller, Kyle S Cole, Corey C Emerson, Dharmaraja Allimuthu, Marcin Golczak, Phoebe L Stewart, Eranthie Weerapana, Drew J Adams, John J Mieyal
Glutaredoxin (Grx1) is a ubiquitously expressed thiol-disulfide oxidoreductase that specifically catalyzes reduction of S-glutathionylated substrates. Grx1 is known to be a key regulator of pro-inflammatory signaling, and Grx1 silencing inhibits inflammation in inflammatory disease models. Therefore, we anticipate that inhibition of Grx1 could be an anti-inflammatory therapeutic strategy. We used a rapid screening approach to test 504 novel electrophilic compounds for inhibition of Grx1, which has a highly reactive active-site cysteine residue (pKa 3...
2017: PloS One
Yasuhiko Izumi, Harue Kataoka, Yuri Inose, Akinori Akaike, Yutaka Koyama, Toshiaki Kume
The nuclear factor erythroid 2-related factor 2 (Nrf2)-antioxidant response element (ARE) pathway, which induces the production of antioxidant enzymes, is a possible therapeutic target for treating diseases related to oxidative stress. Nrf2 activators often exhibit cytotoxicity due to nonspecific electrophilic reactions with thiol groups. We screened a chemical library to explore Nrf2 activators with a wide safety margin. In at least in vitro experiments, TPNA10168, identified from the library, showed a higher efficacy in Nrf2 activation and a lower cytotoxicity than sulforaphane, a well-known Nrf2 activator...
November 14, 2017: European Journal of Pharmacology
Ghiazza Clément, Vincent Debrauwer, Thierry Billard, Anis Tlili
The direct fluoroalkylselenolation of terminal alkynes is reported herein involving shelf stable electrophilic reagents TsSeRF. The use of these reagents allows for the first time performing the reaction under catalytic conditions (copper/ligand). Moroever, the presence of oxygen directing groups allows the selective addition of the reagents to alkynes, therefore yielding a new family of vinyl sulfones.
November 20, 2017: Chemistry: a European Journal
Fabián G Cantú Reinhard, Prasenjit Barman, Gourab Mukherjee, Jitendra Kumar, Deep Kumar, Devesh Kumar, Chivukula V Sastri, Sam P de Visser
Oxygen atom transfer by high-valent enzymatic intermediates remains an enigma in chemical catalysis. In particular, manganese is an important first-row metal involved in key biochemical processes including the biosynthesis of mo-lecular oxygen (through the photosystem II complex) and biodegradation of toxic superoxide to hydrogen peroxide by superoxide dismutase. Biomimetic models of these biological systems have been developed to gain understanding on the structure and properties of short-lived intermediates but also with the aim to create environmentally benign oxidants...
November 17, 2017: Journal of the American Chemical Society
Yunxiang Wu, Zhaoqiang Chen, Yaxi Yang, Weiliang Zhu, Bing Zhou
A Rh(III)-catalyzed unsymmetrical C-H alkylation and amidation of N-phenoxyacetamides with diazo compounds has been developed under mild and redox-neutral conditions, producing dinitrogen as the only by-product. The reaction represents the first example of one-step, unsymmetrical difunctionalization of two orthoC-H bonds. Experimental and computational studies support that N-phenoxyacetamides most likely undergo an initial ortho C-H alkylation with diazo compounds via a Rh(III)-catalyzed C-H activation, and the resulting Rh(III) intermediate subse-quently undergo an intramolecular oxidative addition into the O-N bond to form a Rh(V) nitrenoid species that is pro-tonated and further directed toward electrophilic addition to the second ortho position of the phenyl ring...
November 17, 2017: Journal of the American Chemical Society
Zuowei Xie, Yangjian Quan, Zaozao Qiu
Carboranes are a class of carbon-boron molecular clusters with unusual thermal and chemical stabilities. They have been proved as very useful building blocks in supramolecular design, optoelectronics, nanomaterials, boron neutron capture therapy agents and organometallic/coordination chemistry. Thus, the functionalization of o-carboranes has received growing interests. Over the past decades, most of the works in this area have been focused on cage carbon functionalization as the weakly acidic cage C-H proton can be readily deprotonated by strong bases...
November 17, 2017: Chemistry: a European Journal
Tim Douglas, Anca Pordea, James Dowden
The iron(III)-catalyzed synthesis of indolizines from commercially available alkyne, pyridine, and diazo precursors is reported. This mild, expedient method is tolerant of various solvents and proceeds with as little as 0.25 mol % [Fe(TPP)Cl]. Significantly, this multicomponent reaction is compatible with electrophilic alkynes; control experiments demonstrate the importance of the catalyst in promoting pyridinium ylide formation over background reactivity.
November 16, 2017: Organic Letters
Michela Salamone, Teo Martin, Michela Milan, Miquel Costas, Massimo Bietti
A kinetic study on the HAT reactions from the aliphatic C-H bonds of a series of 1-Z-pentyl, 1-Z-propyl and Z-cyclohexyl derivatives, and of a series of N-alkylamides and N-alkylphthalimides to the electrophilic cumyloxyl radical (CumO•) has been carried out. With 1-pentyl and 1-propyl derivatives, α-CH2 activation towards CumO• is observed for Z = Ph, OH, NH2, NHAc, evidenced by an increase in kH as compared to the unsubstituted alkane substrate. A decrease in kH has been instead measured for Z = OAc, NPhth, CO2Me, Cl, Br, CN, indicative of α-CH2 deactivation with HAT that predominantly occurs from the most remote methylenic site...
November 15, 2017: Journal of Organic Chemistry
Qingqing Bu, Torben Rogge, Vladislav Kotek, Lutz Ackermann
C-H activations with challenging arylacetamides were accomplished by versatile ruthenium(II) biscarboxylate catalysis. The distal C-H functionalization was characterized by ample scope, including twofold oxidative C-H functionalizations and alkyne hydroarylations, through facile base-assisted internal electrophilic-type substitution (BIES) C-H ruthenation by weak O coordination.
November 15, 2017: Angewandte Chemie
Shimon Maksymenko, Keshaba N Parida, Gulab K Pathe, Atul A More, Yuriy B Lipisa, Alex M Szpilman
Herein it is shown, for the first time, that enolonium species are powerful electrophiles capable of reacting with aromatic compounds in an intermolecular manner to afford α-arylated ketones. The reaction is compatible with a variety of functional groups, is of wide scope with respect to aromatic compounds and ketone, and even works for polymerization-prone substrates such as substituted pyrroles, thiophenes, and furans. Only 1.6 to 5 equiv of the commodity aromatic substrates is needed.
November 15, 2017: Organic Letters
Coralie De Schutter, Ozkan Sari, Steven J Coats, Franck Amblard, Raymond Felix Schinazi
A novel and efficient route for the preparation of (2S)-2-chloro-2-fluoro lactone 29 is described. This approach takes advantage of a highly efficient diastereoselective electrophilic fluorination reaction (94% yield; >50:1 dr).
November 15, 2017: Journal of Organic Chemistry
James H W LaFortune, Julia M Bayne, Timothy C Johnstone, Louie Fan, Douglas W Stephan
The electrophilic pyridinium-substituted phenoxy-phosphonium dicationic salt [(PhO)P(2-(N-Mepy))Ph2][B(C6F5)4]2, is shown to be an effective catalyst for the double hydroarylation of alkynes with diarylamines to afford a series of 9-methyl-9-aryl-9,10-dihydroacridine and 9,10-dimethyl-9-aryl-9,10-dihydroacridine derivatives.
November 15, 2017: Chemical Communications: Chem Comm
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