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Jianguang Zhou, Qun Jiang, Peng Fu, Siqian Liu, Sisi Zhang, Su Xu, Qi Zhang
An alternative synthesis of 4-(heteroaryl)cyclohexanones is described, featuring a palladium catalyzed ester α-arylation followed by decarboxylation. The substrate scope is broad with a wide range of heteroaryl halides. Especially, the reaction robustness is demonstrated by the synthesis of >10g of 4-(pyrazin-2-yl)cyclohexanone with a 85% overall yield.
August 17, 2017: Journal of Organic Chemistry
Changhe Zhang, David W Lupton
An enantioselective NHC (N-heterocyclic carbene) catalyzed synthesis of indenes from bifunctional α,β-unsaturated acyl fluorides and TMS enol ethers has been discovered. The reaction has broad generality (31 examples) and proceeds with high levels of enantioselectivity (most >92:8 er). Mechanistically the reaction likely occurs via a Michael/β-lactonization/decarboxylation sequence. Derivatization studies and limitations are discussed.
August 16, 2017: Organic Letters
Xiao-Le Zhou, Lei Ren, Pu-Sheng Wang
The first deacylative allylic C-H alkylation has been established by employing the palladium-catalyzed allylic C-H activation and decarboxylative nucleophile generation. A wide scope of nucleophiles are tolerated and densely functionalized alkylation products turn out to be furnished in moderate to good yield. More importantly, this strategy provides an alternative method for the allylic C-H alkylation with less stabilized carbon nucleophiles, and can be further expanded to the synthesis of unconjugated enynes...
August 15, 2017: Journal of Organic Chemistry
Muliang Zhang, Junwei Xi, Rehanguli Ruzi, Nan Li, Zhongkai Wu, Weipeng Li, Chengjian Zhu
Domino-fluorination-protodefluorination decarboxylative cross-coupling of α-keto acids with styrene has been developed via photoredox catalysis. The critical part of this strategy is the formation of the carbon-fluorine (C-F) bond by the capture of a carbon-centered radical intermediate, which will overcome side reactions during the styrene radical functionalization process. Experimental studies have provided evidence indicating a domino-fluorination-protodefluorination pathway, with α-keto acid initiating the photoredox cycle...
August 15, 2017: Journal of Organic Chemistry
Xinyan Zhang, Kenneth W Bayles, Sorin Luca
Recent studies have revealed an important role for the Staphylococcus aureus CidC enzyme in cell death during the stationary phase and in biofilm development, and have contributed to our understanding of the metabolic processes important in the induction of bacterial programmed cell death (PCD). To gain more insight into the characteristics of this enzyme, we performed an in-depth biochemical and biophysical analysis of its catalytic properties. In vitro experiments show that this flavoprotein catalyzes the oxidative decarboxylation of pyruvate to acetate and carbon dioxide...
August 15, 2017: Biochemistry
Jieyu Zhou, Luying Yang, Alicia DeColli, Caren Freel Meyers, Natalia S Nemeria, Frank Jordan
The enzyme 1-deoxy-d-xylulose 5-phosphate synthase (DXPS) is a key enzyme in the methylerythritol 4-phosphate pathway and is a target for the development of antibiotics, herbicides, and antimalarial drugs. DXPS catalyzes the formation of 1-deoxy-d-xylulose 5-phosphate (DXP), a branch point metabolite in isoprenoid biosynthesis, and is also used in the biosynthesis of thiamin (vitamin B1) and pyridoxal (vitamin B6). Previously, we found that DXPS is unique among the superfamily of thiamin diphosphate (ThDP)-dependent enzymes in stabilizing the predecarboxylation intermediate, C2-alpha-lactyl-thiamin diphosphate (LThDP), which has subsequent decarboxylation that is triggered by d-glyceraldehyde 3-phosphate (GAP)...
August 14, 2017: Proceedings of the National Academy of Sciences of the United States of America
E Lebigot, P Gaignard, I Dorboz, A Slama, M Rio, P de Lonlay, B Héron, F Sabourdy, O Boespflug-Tanguy, A Cardoso, F Habarou, C Ottolenghi, P Thérond, C Bouton, M P Golinelli-Cohen, A Boutron
Lipoic acid (LA) is the cofactor of the E2 subunit of mitochondrial ketoacid dehydrogenases and plays a major role in oxidative decarboxylation. De novo LA biosynthesis is dependent on LIAS activity together with LIPT1 and LIPT2. LIAS is an iron‑sulfur (Fe-S) cluster-containing mitochondrial protein, like mitochondrial aconitase (mt-aco) and some subunits of respiratory chain (RC) complexes I, II and III. All of them harbor at least one [Fe-S] cluster and their activity is dependent on the mitochondrial [Fe-S] cluster (ISC) assembly machinery...
August 3, 2017: Molecular Genetics and Metabolism
Alicia Paz, David Outeiriño, Ricardo Pinheiro de Souza Oliveira, José Manuel Domínguez
Bacillus aryabhattai BA03, a strain isolated in our laboratory, has interesting properties related to the production of natural aromas and flavors. Specifically, we have found that it was able to produce vanillin from ferulic acid (FA). Furthermore, this strain produces high amounts of 4-vinylguaiacol in only 14h, this being the only intermediate metabolite observed in the process. FA is an inexpensive feedstock for the production of natural value-added compounds when extracted from lignocellulosic wastes. In this study, we optimized the operational conditions (temperature, pH and agitation), medium composition and bioconversion technology (batch or fed-batch) to produce vanillin...
August 9, 2017: New Biotechnology
Yizhou Zhao, Yifeng Chen, Timothy R Newhouse
A highly practical and step-economic α,β-dehydrogenation of carboxylic acids via enediolates is reported through the use of allyl-palladium catalysis. Dianions underwent smooth dehydrogenation when generated using Zn(TMP)2-2LiCl as base in the presence of excess ZnCl2, avoiding the typical decarboxylation pathway of these substrates. Direct access to 2-enoic acids allows for derivatization by numerous approaches.
August 10, 2017: Angewandte Chemie
Simon Habran, Thomas Desaive, Philippe Morimont, Bernard Lambermont, Pierre Dauby
The extracorporeal CO2 removal device (ECCO2RD) is used in clinics to treat patients suffering from respiratory failures like acute respiratory distress syndrome (ARDS) or chronic obstructive pulmonary disease (COPD). The aim of this device is to decarboxylate blood externally with low blood flow. A mathematical model is proposed to describe protective ventilation, ARDS, and an extracorporeal CO2 removal therapy (ECCO2RT). The simulations are compared with experimental data carried out on ten pigs. The results show a good agreement between the mathematical simulations and the experimental data, which provides a nice validation of the model...
August 9, 2017: Medical & Biological Engineering & Computing
Jessica Sobotta, Maximilian Schmalhofer, Thomas M Steiner, Wolfgang Eisenreich, Günter Wächtershäuser, Claudia Huber
We report a one-pot formation of 2,4-diolefinic or 2,4,6-triolefinic monocarboxylic acids, R-(CH 000000000000 000000000000 000000000000 111111111111 000000000000 111111111111 000000000000 000000000000 000000000000 CH)2or3-COOH, by decarboxylative condensation of an optionally α,β-unsaturated aldehyde with glutaconic acid, HOOC-CH2-CHCH-COOH as straight chain C4-extender. The reaction is broadly applicable to saturated and unsaturated aldehydes and opens up a simple gateway to valuable organic products and reactive intermediates...
July 2017: Heliyon
Hongbo Ning, Junjun Wu, Liuhao Ma, Wei Ren, David F Davidson, Ronald K Hanson
The potential energy surfaces (PESs) and reaction rate constants of the unimolecular decomposition of ethyl formate (EF) were investigated using high-precision theoretical methods at the CCSD(T)/CBS(T-Q)//M06-2x/6-311++G(d,p) level of theory. The calculated PESs of EF dissociation and molecular decomposition reactions prove that the intramolecular H-shift to produce formic acid and ethylene is the dominant decomposition pathway. A detailed chemical kinetic mechanism for EF pyrolysis was constructed by incorporating the important reactions of EF and its radicals into an existing mechanism previously developed for small methyl esters...
August 9, 2017: Journal of Physical Chemistry. A
Heng Jiang, Armido Studer
The visible-light-promoted decarboxylation of α-imino-oxy propionic acids for the generation of iminyl radicals has been accomplished through the use of Ir(dFCF3ppy)2(dtbbpy)PF6 as a photoredox catalyst. Different from visible-light promoted homolysis and single-electron-reduction of oxime derivatives, this strategy provides a novel catalytic cycle for alkene carboimination through a sequence comprising N-radical generation, iminyl radical cyclization, intermolecular conjugate addition to a Michael acceptor, and single electron reduction to afford various pyrroline derivatives in an overall redox-neutral process...
August 7, 2017: Angewandte Chemie
Liangbin Huang, Astrid M Olivares, Daniel John Weix
A new method for the synthesis of terminal and internal alkynes from the nickel-catalyzed decarboxylative coupling of N-hydroxyphthalimide esters (NHP esters) and bromoalkynes is presented. This reductive cross-electrophile coupling is the first to use a C(sp)-X electrophile, and appears to proceed via an alkynylnickel intermediate. The internal alkyne products are obtained in 41-95% yield without the need for a photocatalyst, light, or strong oxidant. The reaction displays a broad scope of carboxylic acid and alkyne coupling partners and can tolerate an array of functional groups including a carbamate N-H, halogen, nitrile, olefin, ketone, and ester...
August 7, 2017: Angewandte Chemie
Glenn B S Miller, Einar Uggerud
Three deprotonated 2-oxocarboxylic acids, glyoxylate, pyruvate, and 2-oxobutyrate (RCOCO2(-), R = H, CH3, CH3CH2) have been associated with MgCl2 and ZnCl2 to generate [RCOCO2MCl2](-) (M = Mg, Zn) complexes. Upon collision-induced dissociation these complexes all undergo efficient eliminations of CO2 and CO, via an intermediate [RCOMCl2](-) product, to ultimately give [RMCl2](-) products. The pyruvate and 2-oxobutyrate complexes also undergo efficient elimination of HCl to produce the enolate-metal complexes [H2C[double bond, length as m-dash]COCO2MCl](-) and [H3CHC[double bond, length as m-dash]COCO2MCl](-)...
August 16, 2017: Organic & Biomolecular Chemistry
Salette Martinez, Matthias Fellner, Caitlyn Q Herr, Anastasia Ritchie, Jian Hu, Robert P Hausinger
The ethylene-forming enzyme (EFE) from Pseudomonas syringae pv. phaseolicola PK2 is a member of the mononuclear non-heme Fe(II)- and 2-oxoglutarate (2OG)-dependent oxygenase superfamily. EFE converts 2OG into ethylene plus three CO2 molecules while also catalyzing the C5 hydroxylation of L-arginine (L-Arg) driven by the oxidative decarboxylation of 2OG to form succinate and CO2. Here we report eleven X-ray crystal structures of EFE that provide insight into the mechanisms of these two reactions. Binding of 2OG in the absence of L-Arg resulted in predominantly monodentate metal coordination, distinct from the typical bidentate metal-binding species observed in other family members...
August 5, 2017: Journal of the American Chemical Society
Anna Wiśniewska, Rafał Olszanecki, Justyna Totoń-Żurańska, Katarzyna Kuś, Aneta Stachowicz, Maciej Suski, Anna Gębska, Mariusz Gajda, Jacek Jawień, Ryszard Korbut
Atherosclerosis is an inflammatory disease in which dysfunction of mitochondria play an important role, and disorders of lipid management intensify this process. Agmatine, an endogenous polyamine formed by decarboxylation of arginine, exerts a protective effect on mitochondria and modulates fatty acid metabolism. We investigated the effect of exogenous agmatine on the development of atherosclerosis and changes in lipid profile in apolipoprotein E knockout (apoE-/-) mice. Agmatine caused an approximate 40% decrease of atherosclerotic lesions, as estimated by en face and cross-section methods with an influence on macrophage but not on smooth muscle content in the plaques...
August 4, 2017: International Journal of Molecular Sciences
Fan Yang, Dongbin Wei, Ming Xiao, Xuefeng Sun, Qiaorong Guo, Yi Liu, Yuguo Du
Benzophenone-type UV filters are a group of compounds widely used to protect human skin from damage of UV irradiation. Benzophenone-4 (BP-4) was targeted to explore its transformation behaviors during chlorination disinfection treatment in the presence of iodide ions. With the help of ultra performance liquid phase chromatograph and high-resolution quadrupole time-of-flight mass spectrometer, totally fifteen halogenated products were identified, and five out of them were iodinated products. The transformation mechanisms of BP-4 involved electrophilic substitution generating mono- or di-halogenated products, which would be oxidized into esters and further hydrolyzed into phenolic derivatives...
August 2017: Journal of Environmental Sciences (China)
María Angélica Suarez, Jhesua Valencia, Christian Camilo Cadena, Raktim Maiti, Chandreyee Datta, Gloria Puerto, José Hipólito Isaza, Homero San Juan, Valakunja Nagaraja, Juan David Guzman
Tuberculosis continues to be a great source of concern in global health because of the large reservoir of humans infected with the bacilli and the appearance of clinical isolates resistant to a wide array of anti-tuberculosis drugs. New drugs with novel mechanisms of action on new targets are urgently required to reduce global tuberculosis burden. Mycobacterium tuberculosis nucleoid associated protein (NAP) HU has been shown to be druggable and essential for the organism's survival. In this study, four diarylethenes were synthesized using a one-pot decarboxylated Heck-coupling of coumaric acids with iodoanisoles...
July 25, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
Ina Lehmphul, Carolin S Hoefig, Josef Köhrle
PURPOSE: 3-iodothyronamine (3-T1AM), a decarboxylated and deiodinated thyroid hormone metabolite, leads at pharmacological doses to hypoinsulinemia, hyperglucagonemia and hyperglycemia in vivo. As the pancreatic Langerhans islets express thyroid hormone transmembrane transporters (THTT), we tested the hypothesis that not only plasma membrane-mediated 3-T1AM binding to and activation of G-protein coupled receptors, but also 3-T1AM metabolite(s) generated by 3-T1AM uptake and metabolism might decrease glucose-stimulated insulin secretion (GSIS)...
July 25, 2017: Molecular and Cellular Endocrinology
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