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Decarboxylation

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https://www.readbyqxmd.com/read/28211699/cycloalkylation-of-c-sp3-h-bond-with-neighboring-carboxylic-acid-as-a-traceless-activating-group
#1
Leiyang Lv, Zhiping Li
Selective functionalization of inert C(sp3)-H bond is one of cutting-edge challenges in chemical synthesis. A novel strategy for selective C(sp3)-H bond cycloalkylation is developed with neighboring carboxylic acid as a traceless activating group. Primary and secondary alkyl carboxylic acids undergo decarboxylation/α-C(sp3)-H cleavage/cycloalkylation to give the five-membered cyclization products, while tertiary acids undergo decarboxylation/β-C(sp3)-H cleavage/cycloalkylation to generate the six-membered cyclization products...
February 17, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28208655/experimental-evidence-and-in-silico-identification-of-tryptophan-decarboxylase-in-citrus-genus
#2
Luigi De Masi, Domenico Castaldo, Domenico Pignone, Luigi Servillo, Angelo Facchiano
Plant tryptophan decarboxylase (TDC) converts tryptophan into tryptamine, precursor of indolealkylamine alkaloids. The recent finding of tryptamine metabolites in Citrus plants leads to hypothesize the existence of TDC activity in this genus. Here, we report for the first time that, in Citrus x limon seedlings, deuterium labeled tryptophan is decarboxylated into tryptamine, from which successively deuterated N,N,N-trimethyltryptamine is formed. These results give an evidence of the occurrence of the TDC activity and the successive methylation pathway of the tryptamine produced from the tryptophan decarboxylation...
February 11, 2017: Molecules: a Journal of Synthetic Chemistry and Natural Product Chemistry
https://www.readbyqxmd.com/read/28207408/evaluation-of-cannabinoids-concentration-and-stability-in-standardized-preparations-of-cannabis-tea-and-cannabis-oil-by-ultra-high-performance-liquid-chromatography-tandem-mass-spectrometry
#3
Roberta Pacifici, Emilia Marchei, Francesco Salvatore, Luca Guandalini, Francesco Paolo Busardò, Simona Pichini
BACKGROUND: Cannabis has been used since ancient times to relieve neuropathic pain, to lower intraocular pressure, to increase appetite and finally to decrease nausea and vomiting. The combination of the psychoactive cannabis alkaloid Δ9-tetrahydrocannabinol (THC) with the non-psychotropic alkaloids cannabidiol (CBD) and cannabinol (CBN) demonstrated a higher activity than THC alone. The Italian National Institute of Health sought to establish conditions and indications on how to correctly use nationally produced cannabis to guarantee therapeutic continuity in individuals treated with medical cannabis...
February 16, 2017: Clinical Chemistry and Laboratory Medicine: CCLM
https://www.readbyqxmd.com/read/28198184/merging-photoredox-with-copper-catalysis-decarboxylative-alkynylation-of-%C3%AE-amino-acid-derivatives
#4
Hao Zhang, Pengxiang Zhang, Min Jiang, Haijun Yang, Hua Fu
A novel and efficient decarboxylative alkynylation of N-(acetoxy)phthalimides of α-amino acids with terminal alkynes has been developed by merging photoredox with copper catalysis at room temperature, and the reaction provided the valuable propargylamines in good to excellent yields with assistance of [Ru(bpy)3]Cl2/CuI and visible light. The simple protocol, mild reaction conditions, and high efficiency of this method make it an important strategy for synthesis of diverse molecules containing amino acid fragments...
February 15, 2017: Organic Letters
https://www.readbyqxmd.com/read/28195735/doubly-regioselective-c-h-hydroarylation-of-unsymmetrical-alkynes-using-carboxylates-as-deciduous-directing-groups
#5
Agostino Biafora, Bilal A Khan, Janet Bahri, Joachim M Hewer, Lukas J Goossen
A catalyst system composed of [(C6Me6)RuCl2]2, potassium carbonate/guanidine carbonate, and mesitoic acid efficiently promotes the doubly regioselective C-H hydroarylation of unsymmetrical alkynes. The process involves carboxylate-directed ortho-C-H bond activation followed by regioselective addition to the alkyne C-C triple bond with concerted decarboxylation. This action of the carboxylate as a deciduous directing group ensures exclusive monovinylation with high selectivity for the (E)-1,2-diarylalkene.
February 14, 2017: Organic Letters
https://www.readbyqxmd.com/read/28188209/identification-and-characterization-of-a-novel-three-component-phenazine-1-carboxylic-acid-1-2-dioxygenase-in-sphingomonas-wittichii-dp58
#6
Qiang Zhao, Hong-Bo Hu, Wei Wang, Xian-Qing Huang, Xue-Hong Zhang
Phenazine-1-carboxylic acid, the main component of shenqinmycin, is widely used in southern China for the prevention of rice sheath blight. However, the fate of phenazine-1-carboxylic acid in soil remains uncertain. S. wittichii DP58 can use phenazine-1-carboxylic acid as its sole carbon and nitrogen sources for growth. In this study, dioxygenase-encoding genes, pcaA1A2, were found using transcriptome analysis to be highly upregulated upon phenazine-1-carboxylic acid biodegradation. PcaA1 shares 68% amino acid sequence identity with the large oxygenase subunit of anthranilate 1, 2-dioxygenase from R...
February 10, 2017: Applied and Environmental Microbiology
https://www.readbyqxmd.com/read/28185368/alkyl-hetero-aryl-bond-formation-via-decarboxylative-cross-coupling-a-systematic-analysis
#7
Frederik Sandfort, Matthew J O'Neill, Josep Cornella, Laurin Wimmer, Phil S Baran
Suzuki, Negishi, and Kumada couplings are some of the most important reactions for the formation of skeletal C-C linkages. Their widespread use to forge bonds between two aromatic rings has enabled every branch of chemical science. The analogous union between alkyl halides and metallated aryl systems has not been as widely employed due to the lack of commercially available halide building blocks. Redox-active esters have recently emerged as useful surrogates for alkyl halides in cross-coupling chemistry. Such esters are easily accessible through reactions between ubiquitous carboxylic acids and coupling agents widely used in amide bond formation...
February 10, 2017: Angewandte Chemie
https://www.readbyqxmd.com/read/28181804/rhodium-iii-catalyzed-ortho-alkylation-of-phenoxy-substrates-with-diazo-compounds-via-c-h-activation-a-case-of-decarboxylative-pyrimidine-pyridine-migratory-cyclization-rather-than-removal-of-pyrimidine-pyridine-directing-group
#8
Manjula Ravi, Srinivasarao Allu, K C Kumara Swamy
An efficient Rh(III)-catalyzed ortho-alkylation of phenoxy substrates with diazo compounds has been achieved for the first time using pyrimidine or pyridine as the directing group. Furthermore, bis-alkylation has also been achieved using para-substituted phenoxypyrimidine using 3 mole equiv of the diazo ester. The ortho-alkylated derivatives of phenoxy products possessing the ester functionality undergo decarboxylative pyrimidine/pyridine migratory cyclization (rather than deprotection of pyrimidine/pyridine group) using 20% NaOEt in EtOH affording a novel class of 3-(pyrimidin-2(1H)-ylidene)benzofuran-2(3H)-ones and 6-methyl-3-(pyridin-2(1H)-ylidene)benzofuran-2(3H)-one...
February 9, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28179946/diastereoselective-anodic-hetero-and-homo-coupling-of-menthol-8-methylmenthol-and-8-phenylmenthol-2-alkylmalonates
#9
Matthias C Letzel, Hans J Schäfer, Roland Fröhlich
Diastereoselective radical coupling was achieved with chiral auxiliaries. The radicals were generated by anodic decarboxylation of five malonic acid derivatives. These were prepared from benzyl malonates and four menthol auxiliaries. Coelectrolyses with 3,3-dimethylbutanoic acid in methanol at platinum electrodes in an undivided cell afforded hetero-coupling products in 22-69% yield with a diastereoselectivity ranging from 5 to 65% de. Electrolyses without a coacid led to diastereomeric homo-coupling products in 21-50% yield with ratios of diastereomers being 1...
2017: Beilstein Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28165474/photo-driven-redox-neutral-decarboxylative-carbon-hydrogen-trifluoromethylation-of-hetero-arenes-with-trifluoroacetic-acid
#10
Jin Lin, Zhi Li, Jian Kan, Shijun Huang, Weiping Su, Yadong Li
Catalytic oxidative C-H bond functionalization reactions that proceed without requiring stoichiometric amounts of external oxidants or pre-functionalized oxidizing reagents could maximize the atom- and step-economy in chemical syntheses. However, such a transformation remains elusive. Here, we report that a photo-driven catalytic process enables decarboxylative C-H trifluoromethylation of (hetero)arenes with trifluoroacetic acid as a trifluoromethyl source in good yields in the presence of an external oxidant in far lower than stoichiometric amounts (for example, 0...
February 6, 2017: Nature Communications
https://www.readbyqxmd.com/read/28157306/mechanism-and-stereochemistry-of-polyketide-chain-elongation-and-methyl-group-epimerization-in-polyether-biosynthesis
#11
Xinqiang Xie, Ashish Garg, Chaitan Khosla, David E Cane
The polyketide synthases responsible for the biosynthesis of the polyether antibiotics nanchangmycin (1) and salinomycin (4) harbor a number of redox-inactive ketoreductase (KR(0)) domains that are implicated in the generation of C2-epimerized (2S)-2-methyl-3-ketoacyl-ACP intermediates. Evidence that the natural substrate for the polyether KR(0) domains is, as predicted, a (2R)-2-methyl-3-ketoacyl-ACP intermediate, came from a newly developed coupled ketosynthase (KS)-ketoreductase (KR) assay that established that the decarboxylative condensation of methylmalonyl-CoA with S-propionyl-N-acetylcysteamine catalyzed by the Nan[KS1][AT1] didomain from module 1 of the nanchangmycin synthase generates exclusively the corresponding (2R)-2-methyl-3-ketopentanoyl-ACP (7a) product...
February 14, 2017: Journal of the American Chemical Society
https://www.readbyqxmd.com/read/28150496/synthesis-of-n-sulfonyl-amidines-and-acyl-sulfonyl-ureas-from-sulfonyl-azides-carbon-monoxide-and-amides
#12
Shiao Y Chow, Luke R Odell
A Pd-catalyzed and ligand-free carbonylation/cycloaddition/decarboxylation cascade synthesis of sulfonyl amidines from sulfonyl azides and substituted amides at low CO pressure is reported. The reaction proceeds via an initial Pd-catalyzed carbonylative generation of sulfonyl isocyanates from sulfonyl azides, followed by a [2 + 2] cycloaddition with amides and subsequent decarboxylation, which liberates the desired sulfonyl amidines, generating N2 and CO2 as the only reaction byproducts. Using this simple protocol, a diverse range of sulfonyl amidines was obtained in moderate to excellent yields...
February 15, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28145722/base-promoted-decarboxylative-azo-coupling-construction-of-unsymmetrical-azocarboranes
#13
Huan-Huan Li, Fan Bai, Hong Yan, Chang-Sheng Lu
Base-promoted decarboxylative azo couplings of carboranyl carboxylic acids with diazo salts have been developed to provide trans-azocarboranes in high yields (up to 94%). This approach is simple, efficient, and compatible with various functional groups. Mechanistically, the coupling has been proven to proceed in a nonradical pathway, which is distinct from those classical decarboxylative couplings.
February 1, 2017: Organic Letters
https://www.readbyqxmd.com/read/28139779/the-%C3%AE-and-%C3%AE-subunits-play-distinct-functional-roles-in-the-%C3%AE-2%C3%AE-%C3%AE-heterotetramer-of-human-nad-dependent-isocitrate-dehydrogenase
#14
Tengfei Ma, Yingjie Peng, Wei Huang, Yabing Liu, Jianping Ding
Human NAD-dependent isocitrate dehydrogenase existing as the α2βγ heterotetramer, catalyzes the decarboxylation of isocitrate into α-ketoglutarate in the Krebs cycle, and is allosterically regulated by citrate, ADP and ATP. To explore the functional roles of the regulatory β and γ subunits, we systematically characterized the enzymatic properties of the holoenzyme and the composing αβ and αγ heterodimers in the absence and presence of regulators. The biochemical and mutagenesis data show that αβ and αγ alone have considerable basal activity but the full activity of α2βγ requires the assembly and cooperative function of both heterodimers...
January 31, 2017: Scientific Reports
https://www.readbyqxmd.com/read/28138829/metabolism-and-disposition-of-the-anticancer-quinolone-derivative-vosaroxin-a-novel-inhibitor-of-topoisomerase-ii
#15
C M Nijenhuis, L Lucas, H Rosing, A D R Huitema, M Mergui-Roelvink, G C Jamieson, J A Fox, D R Mould, J H M Schellens, J H Beijnen
Background Vosaroxin is a first-in-class anticancer quinolone derivative that is being investigated for patients with relapsed or refractory acute myeloid leukemia (AML). The primary objective of this study was to quantitatively determine the pharmacokinetics of vosaroxin and its metabolites in patients with advanced solid tumors. Methods This mass balance study investigated the pharmacokinetics (distribution, metabolism, and excretion) of vosaroxin in cancer patients after a single dose of 60 mg/m(2 14)C-vosaroxin, administered as short intravenous injection...
January 31, 2017: Investigational New Drugs
https://www.readbyqxmd.com/read/28128651/the-importance-of-lactic-acid-bacteria-for-the-prevention-of-bacterial-growth-and-their-biogenic-amines-formation-a-review
#16
Fatih Özogul, Imen Hamed
Foodborne pathogens (FBP) represent an important threat to the consumers' health as they are able to cause different foodborne diseases. In order to eliminate the potential risk of those pathogens, lactic acid bacteria (LAB) have received a great attention in the food biotechnology sector since they play an essential function to prevent bacterial growth and reduce the biogenic amines formation. The foodborne illnesses (diarrhea, vomiting, and abdominal pain etc.) caused by those microbial pathogens is due to various reasons, one of them is related to the decarboxylation of available amino acids that lead to biogenic amines (BAs) production...
January 27, 2017: Critical Reviews in Food Science and Nutrition
https://www.readbyqxmd.com/read/28127095/improved-simplicity-and-practicability-in-copper-catalyzed-alkynylation-of-tetrahydroisoquinoline
#17
Birgit Gröll, Patricia Schaaf, Michael Schnürch
ABSTRACT: Alkynylation reactions of N-protected tetrahydroisoquinolines have been performed using several different protocols of cross dehydrogenative coupling. Initially, a CuCl-catalyzed method was investigated, which worked well with three different N-protecting groups, namely phenyl, PMP, and benzyl and t-BuOOH as oxidant in acetonitrile as solvent. The peroxide could then be replaced by simple air and acetonitrile for water, leading to an overall very environmentally friendly protocol...
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28127091/synthesis-of-%C3%AE-pyrones-via-decarboxylative-condensation-of-%C3%AE-ketoacids
#18
Jérémy Merad, Thomas Maier, Catarina A B Rodrigues, Nuno Maulide
ABSTRACT: This manuscript describes the convergent synthesis of aryl- and alkyl-disubstituted γ-pyrones from β-ketoacids. The reaction proceeds in the presence of trifluoromethanesulfonic anhydride via an unprecedented decarboxylative auto-condensation of the starting material. Herein, the scope and limitations of this transformation are reported. GRAPHICAL ABSTRACT: HASH(0x3544350)
2017: Monatshefte Für Chemie
https://www.readbyqxmd.com/read/28126587/co-option-of-the-sphingolipid-metabolism-for-the-production-of-nitroalkene-defensive-chemicals-in-termite-soldiers
#19
Anna Jirošová, Andrej Jančařík, Riya C Menezes, Olga Bazalová, Klára Dolejšová, Heiko Vogel, Pavel Jedlička, Aleš Buček, Jana Brabcová, Pavel Majer, Robert Hanus, Aleš Svatoš
The aliphatic nitroalkene (E)-1-nitropentadec-1-ene (NPD), reported in early seventies in soldiers of the termite genus Prorhinotermes, was the first documented nitro compound produced by insects. Yet, its biosynthetic origin has long remained unknown. Here, we investigated in detail the biosynthesis of NPD in P. simplex soldiers. First, we track the dynamics in major metabolic pathways during soldier ontogeny, with emphasis on likely NPD precursors and intermediates. Second, we propose a hypothesis of NPD formation and verify its individual steps using in vivo incubations of putative precursors and intermediates...
January 23, 2017: Insect Biochemistry and Molecular Biology
https://www.readbyqxmd.com/read/28124826/rhodium-catalyzed-decarbonylative-borylation-of-aromatic-thioesters-for-facile-diversification-of-aromatic-carboxylic-acids
#20
Hidenori Ochiai, Yuta Uetake, Takashi Niwa, Takamitsu Hosoya
Transformation of aromatic thioesters into arylboronic esters was achieved efficiently using a rhodium catalyst. The broad functional-group tolerance and mild conditions of the method have allowed for the two-step decarboxylative borylation of a wide range of aromatic carboxylic acids, including commercially available drugs.
January 26, 2017: Angewandte Chemie
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