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heterocyclic amines

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https://www.readbyqxmd.com/read/29792430/buchwald-hartwig-amination-of-phosphinines-and-the-effect-of-amine-substituents-on-optoelectronic-properties-of-the-resulting-coupling-products
#1
Noriyoshi Nagahora, Shoko Goto, Takahiro Inatomi, Hiroshi Tokumaru, Kouki Matsubara, Kosei Shioji, Kentaro Okuma
The Buchwald-Hartwig amination of a phosphinine bearing a bromophenyl moiety was carried out using a dinuclear Ni catalyst. A variety of monoarylamines, diarylamines, and alkylamine, as well as heterocycles, were successfully converted into novel phosphinines bearing amine units. The photophysical properties of these novel phosphinines were examined, including the substituent-dependent absorption/emission features and intramolecular charge-transfer interactions.
May 24, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29789822/inhibitory-effects-of-catechins-on-%C3%AE-carbolines-in-tea-leaves-and-chemical-model-systems
#2
Ye Jiao, Yan Yan, Zhiyong He, Daming Gao, Fang Qin, Mei Lu, Mingyong Xie, Jie Chen, Maomao Zeng
The profile of 18 heterocyclic amines from seven categories (including β-carbolines) in tea leaves during green and black tea processing procedures, as well as commercial tea products was screened by ultrahigh-performance liquid chromatography with tandem mass spectrometry. 2-Amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhIP), 2-amino-3,4-dimethylimidazo[4,5-f]quinoline (MeIQ), and 2-amino-3,8-dimethyl-imidazo[4,5-f]quinoxaline (MeIQx) were detected in samples; however, the levels were too low for quantification...
May 23, 2018: Food & Function
https://www.readbyqxmd.com/read/29774978/n-heterocyclic-carbene-protected-ag-nanoparticles-immobilized-on-polyacrylonitrile-fiber-as-efficient-catalysts-for-a-three-component-coupling-reaction
#3
Jian Cao, Hongqi Tian
Metal nanoparticles (NPs) are routinely stabilized by the introduction of capping agents or their distribution on supports. In this context, we report the preparation and characterization of N-heterocyclic carbene (NHC)-stabilized silver NPs supported on polyacrylonitrile fiber (PANF). As a result, Ag loadings of up to 8 % and particle sizes of 11.0±3.2 nm were achieved. This novel nanocomposite catalyst demonstrated high activity in addition to excellent stability and reusability in the three-component reaction between alkynes, haloalkanes, and amines...
May 18, 2018: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/29764743/design-synthesis-and-evaluation-of-photoactivatable-derivatives-of-microtubule-mt-active-1-2-4-triazolo-1-5-a-pyrimidines
#4
Killian Oukoloff, Jane Kovalevich, Anne-Sophie Cornec, Yuemang Yao, Zachary A Owyang, Michael James, John Q Trojanowski, Virginia M-Y Lee, Amos B Smith, Kurt R Brunden, Carlo Ballatore
The [1,2,4]triazolo[1,5-a]pyrimidines comprise a promising class of non-naturally occurring microtubule (MT)-active compounds. Prior studies revealed that different triazolopyrimidine substitutions can yield molecules that either promote MT stabilization or disrupt MT integrity. These differences can have important ramifications in the therapeutic applications of triazolopyrimidines and suggest that different analogues may exhibit different binding modes within the same site or possibly interact with tubulin/MTs at alternative binding sites...
May 5, 2018: Bioorganic & Medicinal Chemistry Letters
https://www.readbyqxmd.com/read/29758895/chemical-speciation-including-polycyclic-aromatic-hydrocarbons-pahs-and-toxicity-of-particles-emitted-from-meat-cooking-operations
#5
Nicholas Gysel, Poornima Dixit, Debra A Schmitz, Guenter Engling, Arthur K Cho, David R Cocker, Georgios Karavalakis
We assessed the chemical properties and oxidative stress of particulate matter (PM) emissions from underfired charbroiled meat operations with and without the use of aftertreatment control technologies. Cooking emissions concentrations showed a strong dependence on the control technology utilized, with all emission rates showing decreases with the control technologies compared to the baseline testing. The organic acids profile was dominated by the saturated nonanoic, myristic, palmitic, and stearic acids, and the unsaturated oleic, elaidic, and palmitoleic acids...
August 15, 2018: Science of the Total Environment
https://www.readbyqxmd.com/read/29756782/regioselective-synthesis-of-acylated-n-heterocycles-via-the-cascade-reactions-of-saturated-cyclic-amines-with-2-oxo-2-arylacetic-acids
#6
Xiaonan Shi, Xi Chen, Muhua Wang, Xinying Zhang, Xuesen Fan
A highly regioselective and versatile synthesis of acylated N-heterocycles from the cascade reactions of saturated cyclic amines with 2-oxo-2-arylacetic acids is presented. Mechanistically, the formation of the title compounds involves firstly a C(sp3)-H bond dehydrogenation of cyclic amine to give an enamine intermediate followed by its cross coupling with the acyl species in situ generated through the decarboxylation of 2-oxo-2-arylacetic acid. Interestingly, in this cascade process the copper catalyst is believed to play a crucial role not only in dehydrogenation, but also in decarboxylation and cross coupling reaction...
May 14, 2018: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/29756660/synthesis-of-azo-dyes-from-mesoionic-carbenes-and-nitrous-oxide
#7
Léonard Y M Eymann, Rosario Scopelliti, Farzaneh Fadaei Tirani, Kay Severin
Covalent adducts of imidazole-based mesoionic carbenes and nitrous oxide (N2 O, "laughing gas") can be converted into azo dyes by reaction with arenes in the presence of AlCl3 or HCl. The azo coupling can be achieved with electron-rich aromatic compounds such as mesitylene, trimethoxybenzene, azulene, or dibenzo-18-crown-6. The latter coupling reaction allows for the easy preparation of a colorimetric sensor for potassium or sodium ions. As a putative intermediate of the reaction with acid, we were able to isolate and structurally characterize a rare diazohydroxide...
May 14, 2018: Chemistry: a European Journal
https://www.readbyqxmd.com/read/29756659/fragmentation-pathways-arising-from-protonation-at-different-sites-in-aminoalkyl-substituted-3-hydroxy-1-2-5-oxadiazoles-3-hydroxyfurazans
#8
J Stuart Grossert, Donatella Boschi, Marco L Lolli, Robert L White
RATIONALE: The gas-phase fragmentation chemistry of multifunctional cations is highly influenced by the site of protonation. Possible relationships between protonation site and fragmentation processes were studied using 4-aminoalkyl-3-hydroxyfurazans. For these heterocyclic amines, the starting points for competing fragmentation pathways varied with protonation at multiple sites in two tautomers. METHODS: Mass spectra were acquired using electrospray ionization (ESI, positive mode) coupled to triple quadrupole and ion trap mass spectrometers; precursor-product ion relationships were studied by collision induced dissociation (CID)...
May 14, 2018: Rapid Communications in Mass Spectrometry: RCM
https://www.readbyqxmd.com/read/29751128/the-adenomatous-polyposis-coli-apc-mutation-spectra-in-different-anatomical-regions-of-the-large-intestine-in-colorectal-cancer
#9
Min Zhang, Da Yang, Barry Gold
The enhanced incidence of colorectal cancer (CRC) in the U.S.A. has been linked to promutagens, such as heterocyclic aromatic amines, in the western diet that are produced by high temperature cooking of meat. However, a prior analysis of driver nonsense mutations in the Adenomatous Polyposis Coli (APC) gene, which is mutated in 75% of human CRC, indicated that the C·G → A·T transversions produced by this class of mutagens were not enriched but actually lower than what would be statistically anticipated...
May 1, 2018: Mutation Research
https://www.readbyqxmd.com/read/29742319/a-general-palladium-phosphine-complex-for-exploring-aryl-tosylates-in-n-arylation-of-amines-scope-and-limitation
#10
Pui Ying Choy, Kin Ho Chung, Qingjing Yang, Chau Ming So, Raymond Wai-Yin Sun, Fuk Yee Kwong
The scope and limitation of mono-selective N-arylation of various amines using aryl or heteroaryl tosylates are presented. Air-stable and easily accessible Pd(OAc)2/CM-phos catalyst system was found capable to deal with a wide range of aryl tosylate substrates as well as amine nucleophiles, including primary and secondary cyclic/acyclic aliphatic amines, and anilines. NH-bearing heterocycles such as indole, carbazole, pyrrole, 10-phenothiazine and 10-phenoxazine were shown to be feasible coupling partners under this catalytic system...
May 9, 2018: Chemistry, An Asian Journal
https://www.readbyqxmd.com/read/29738248/regioselective-metalation-and-functionalization-of-the-pyrazolo-1-5-a-pyridine-scaffold-using-mg-and-zn-tmp-bases
#11
Moritz Balkenhohl, Bruno Salgues, Takahiro Hirai, Konstantin Karaghiosoff, Paul Knochel
A regioselective functionalization of the pyrazolo[1,5- a]pyridine scaffold using Mg- and Zn-TMP bases (TMP = 2,2,6,6-tetramethylpiperidyl) in the presence or absence of BF3 ·OEt2 is described. Also, various functionalized pyrazolo[1,5- a]pyridines bearing an ester function (and an NHBoc or ethyl group) are magnesiated and functionalized, leading to polysubstituted heterocycles. Additionally, a sulfoxide directed ortho-metalation, followed by the transition-metal-free amination of a pyrazolo[1,5- a]pyridine sulfoxide, using a magnesium amide, is reported...
May 8, 2018: Organic Letters
https://www.readbyqxmd.com/read/29737487/concentrations-of-selected-heterocyclic-aromatic-amines-among-us-population-aged-%C3%A2-6-years-data-from-nhanes-2013-2014
#12
Ram B Jain
Data from National Health and Nutrition Examination Survey for US population aged ≥ 6 years for 2013-2014 were used to analyze data for four heterocyclic aromatic amines (HCAA), namely 2-amino-9H-pyrido[2,3-b]indole (AαC), 2-amino-1-methyl-6-phenylimidazo[4,5-b]pyridine (PhlP), harman, and norharman. Data were analyzed separately for children aged 6-11 years (N = 416), adolescents aged 12-19 years (N = 475), adults aged 20-64 years (N = 1913), and seniors aged ≥ 65 years (N = 458)...
May 8, 2018: Environmental Science and Pollution Research International
https://www.readbyqxmd.com/read/29731443/2-5-substituted-phenyl-1-3-4-oxadiazol-2-yl-sulfanyl-n-1-3-thiazol-2-yl-acetamides-new-bi-heterocycles-as-possible-therapeutic-agents
#13
Muhammad Shahid Ramzan, Muhammad Athar Abbasi, Azizur Rehman, Sabahat Zahra Siddiqui, Syed Adnan Ali Shah, Muhammad Ashraf, Bushra Mirza, Hammad Ismail
An electrophile, N-(1,3-thiazol-2-yl)-2-bromoacetamide (3), was synthesized by the reaction of 1,3-thiazole-2-amine (1) and 2-bromoethanoyl bromide (2) in an aqueous medium. A series of carboxylic acids, 7a-j, were converted into 1,3,4-oxadiazole heterocyclic core, through a series of three steps. The final compounds, 8a-j, were synthesized by stirring 7a-j and 3 in an aprotic polar solvent. The structural elucidation of the synthesized compounds was supported by IR, EI-MS, 1H-NMR, and 13 C-NMR spectral data...
May 2018: Pakistan Journal of Pharmaceutical Sciences
https://www.readbyqxmd.com/read/29719155/oxidative-modification-of-tryptophan-containing-peptides
#14
Jonas Odgaard Petersen, Katrine Englund Christensen, Mathias Thor Nielsen, Kim Thollund Mortensen, Vitaly Komnatnyy, Thomas Eiland Nielsen, Katrine Qvortrup
Fluorescence labeling of proteins and peptides is fundamental for the study of biological systems, as it can provide detailed visualization of complex molecular mechanisms. This approach has been crucial for our understanding of molecular dynamics and led to the development of new potent drugs. Nowadays, the most common approach to fluorescence labeling compresses introduction of carbo- and heterocyclic molecules to the nucleophilic side chain of lysine, serine, threonine and cysteine in the peptide sequence of interest...
May 2, 2018: ACS Combinatorial Science
https://www.readbyqxmd.com/read/29713716/synthesis-structures-and-luminescence-properties-of-amine-bis-n-heterocyclic-carbene-copper-i-and-silver-i-complexes
#15
Taotao Lu, Jin-Yun Wang, Lin-Xi Shi, Zhong-Ning Chen, Xue-Tai Chen, Zi-Ling Xue
A series of Ag(i) and Cu(i) complexes [Ag3(L1)2][PF6]3 (8), [Ag3(L2)2][PF6]3 (9), [Cu(L1)][PF6] (10) and [Cu(L2)][PF6] (11) have been synthesized by reactions of the tridentate amine-bis(N-heterocyclic carbene) ligand precursors [H2L1][PF6]2 (6) and [H2L2][PF6]2 (7) with Ag2O and Cu2O, respectively. Complexes 10 and 11 can also be obtained by transmetalation of 8 and 9, respectively, with 3.0 equiv. of CuCl. A heterometallic Cu/Ag-NHC complex [Cu2Ag(L1)2(CH3CN)2][PF6]3 (12) is formed by the reaction of 8 with 2...
May 1, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
https://www.readbyqxmd.com/read/29710041/synthesis-surface-parameters-and-biodegradability-of-water-soluble-surfactants-for-various-applications
#16
Refat El-Sayed, Hawazin H Alotaibi, Heba A Elhady
The synthesis of water-soluble heterocyclic compounds was verified on the basis of nonionic surfactants for use as surface-active agents. Surface characteristics such as surface and interfacial tensions, cloud point, wetting time, emulsion stability, foaming height and foaming stability were measured for these surface factors in aqueous solutions. In addition, the critical micelle concentration (CMC), the surface pressure at CMC (πcmc ), the effectiveness of surface tension reduction (pC20 ), the maximum surface concentration (Γma...
2018: Journal of Oleo Science
https://www.readbyqxmd.com/read/29708723/still-unconquered-enantioselective-passerini-and-ugi-multicomponent-reactions
#17
Qian Wang, De-Xian Wang, Mei-Xiang Wang, Jieping Zhu
The Passerini three-component (P-3CR) and the Ugi four-component (U-4CR) are two of the most prominent isocyanide-based multicomponent reactions (IMCRs). The P-3CR transforms isocyanides, aldehydes (ketones), and carboxylic acids to α-acyloxy carboxamides, while the U-4CR converts isocyanides, aldehydes (ketones), amines, and carboxylic acids to α-acetamido carboxamides. Conversion of the high energy formal divalent isocyano carbon into a tetravalent amide carbonyl carbon provides the driving force for these reactions...
April 30, 2018: Accounts of Chemical Research
https://www.readbyqxmd.com/read/29708346/synthesis-of-pyrimidopyrrolopyridazines-via-a-tandem-reaction-of-heterocyclic-ketene-aminals-with-1-2-diaza-1-3-dienes
#18
Menghao Zhao, Xia Li, Jiaan Shao, Wenteng Chen, Ning Xie, Hu Yuan, Qingyan Sun, Weidong Zhang
A tandem reaction of heterocyclic ketene aminals and 1,2-diaza-1,3-dienes was developed for the expedient synthesis of pyrimidopyrrolopyridazine derivatives. This process involved an intramolecular conjugate addition followed by CuCl2 -catalyzed hydrazone formation.
April 30, 2018: Organic Letters
https://www.readbyqxmd.com/read/29693756/enantioselective-hydroamidation-of-enals-by-trapping-of-a-transient-acyl-species
#19
Pengfei Yuan, Jiean Chen, Jing Zhao, Yong Huang
An enantioselective synthesis of β-chiral amides by asymmetric and redox-neutral hydroamidation of enals is reported. In this reaction, a chiral N-heterocyclic carbene (NHC) catalyst reacts with enals to generate the homoenolate intermediate. Upon highly enantioselective β-protonation via proton-shuttle catalysis, the resulting azolium intermediate reacts with imidazole to yield the key β-chiral acyl species. This transient intermediate provides access to diversified β-chiral carbonyl derivatives, such as amides, hydrazides, acids, esters, and thioesters...
April 25, 2018: Angewandte Chemie
https://www.readbyqxmd.com/read/29689357/red-meat-and-colon-cancer-a-review-of-mechanistic-evidence-for-heme-in-the-context-of-risk-assessment-methodology
#20
REVIEW
Claire Kruger, Yuting Zhou
On October 26, 2015, IARC published a summary of their findings regarding the association of cancer with consumption of red meat or processed meat (IARC 2015a; The Lancet Oncology 2015). The Working Group concluded that there is limited evidence in human beings for carcinogenicity from the consumption of red meat and inadequate evidence in experimental animals for the carcinogenicity of consumption of red meat. Nevertheless, the working group concluded that there is strong mechanistic evidence by which ingestion of red meat can be linked to human colorectal cancer and assigned red meat to Group 2A "probably carcinogenic to humans"...
April 21, 2018: Food and Chemical Toxicology
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