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Hang Yu, Yi-Xin Seow, Peter K C Ong, Weibiao Zhou
A kinetic model for a high-intensity ultrasound-assisted Maillard reaction model system of d-glucose and glycine was proposed; activation energy (Ea) for each reaction step was calculated. Results showed that the generation of dicarbonyl compounds was significantly promoted by high-intensity ultrasound (e.g. Ea values for 1-deoxyglucosone were 60.9 ± 9.7 kJ mol-1 and 105.5 ± 9.9 kJ mol-1 in ultrasonic and thermal Maillard reaction, respectively), which resulted in a significantly higher concentration of colored and volatile Maillard reaction products generated in ultrasound-assisted Maillard reaction compared with that in thermal Maillard reaction...
December 15, 2018: Food Chemistry
Gang Xu, Chaodi Tong, Sunliang Cui, Liyan Dai
A silver catalyzed domino reaction of N-cyanamide alkenes and 1,3-dicarbonyls including 1,3-diketones and ethyl acetoacetate has been developed for the facile synthesis of quinazolinones. In the presence of AgNO3/K2S2O8, the diketones could be converted to radicals and coupled with N-cyanamide alkenes to undergo a cyclization cascade for accessing quinazolinones. This method features mild reaction conditions, readily available starting materials, and valuable synthetic utility. Moreover, the products could be further transformed into various heterocycles...
August 3, 2018: Organic & Biomolecular Chemistry
Xingxing Ma, Yao Zhou, Qiuling Song
An efficient and practical strategy for the synthesis of β-aminoenones from a three-component reaction was developed. Ethyl bromodifluoroacetate serves as a C1 source in this strategy, forming isocyanides in situ with primary amines. This reaction represents the first example of utilization of readily available starting materials to generate isocyanides in situ and sequentially fully converted to β-aminoenones, avoiding the generation of byproduct imines and overinsertion products. The mechanism study suggested that this method involves activation of two C(sp3 )-F bonds and the formation of isocyanides, which might nourish both isocyanide chemistry and fluorine chemistry...
August 1, 2018: Organic Letters
Marco Paolo Jacinto, Patricio Pichling, Marc M Greenberg
A facile, one-pot synthetic method for the synthesis of 5-methylene-2-pyrrolones (5MPs) from inexpensive furfuryl acetate is described. Bromine oxidation and trapping of the in situ generated 1,4-dicarbonyl compound by a primary amine provided the corresponding 5MPs in 50-69% yield.
July 31, 2018: Organic Letters
Silvia Roscales, Víctor Ortega, Aurelio G Csákÿ
The repertoire of synthetic transformations of the products of the Achmatowicz rearrangement has been expanded by exploring their reactivity with potassium organotrifluoroborates in the absence of transition metals. Depending on the reaction conditions and the substitution pattern of the starting material, the reaction may lead to the stereoselective synthesis of dihydropyranones (2,6- trans), tetrahydropyranones (2,3- cis-2,6- cis) or functionalized 1,4-dicarbonyl compounds. The method has also been adapted for the one-pot synthesis of functionalized pyrroles...
August 2, 2018: Journal of Organic Chemistry
Pervaiz Ali Channar, Saira Afzal, Syeda Abida Ejaz, Aamer Saeed, Fayaz Ali Larik, Parvez Ali Mahesar, Joanna Lecka, Jean Sévigny, Mauricio F Erben, Jamshed Iqbal
In the present work we report the synthesis of new aryl pyrazole derivatives using 1,3-dicarbonyl motifs. The reaction was proceeded by the cyclization of pentane-2,4-dione (1a), 3-chloropentane-2,4-dione (1b) or ethyl 3-oxobutanoate (1c) with different aryl hydrazines. The products, which can be regarded as 1H-pyrazol-1-yl-one analogues (3a-f, 3g-o, 4a-c, 5a-b) and represent drug like molecules along with well-developed structure-activity relationships, were obtained in good to excellent yield. The structures of synthesized compounds were charcterized on the basis of FT-IR, 1 H NMR, 13 C NMR and mass spectroscopic data...
July 7, 2018: European Journal of Medicinal Chemistry
Michael A Land, Bright Huo, Katherine N Robertson, Kai E O Ylijoki, Peter T K Lee, Jetsuda Areephong, Dragoslav Vidović, Jason A C Clyburne
In this paper we describe the synthesis, characterization, and X-ray crystal structures of two ligands, diethyl-N,N'-bis(p-tolyl)malonimidate and 1,3-bis(dimethylamino)-N,N'-bis(p-tolyl)propanediimidate. Their corresponding rhodium(i) dicarbonyl, dimethylaluminium, and bis-ligated zinc complexes have also been prepared and characterized. The donor properties of the ligands have been studied and have been compared to those of the traditional anionic N,N'-chelating ligand nacnac.
July 31, 2018: Dalton Transactions: An International Journal of Inorganic Chemistry
Adnan Cetin, Adem Korkmaz, Ishak Bildirici
Pyrazole-3,4-dicarboxylic acid 2 was synthesized via the hydrolysis of pyrazole-3-carboxylic acid 1 and subsequently heated with thionyl chloride to give the novel pyrazole-3,4-dicarbonyl dichloride 3 , which was easily converted into oligo-pyrazole 4 upon its reaction with p -phenylene-diamine. These newly synthesized compounds were characterized by 1 H-NMR, 13 C-NMR, and FT-IR spectroscopy, and gel permission chromatography (GPC). Three novel oligo-pyrazole thin films were prepared using oligo-pyrazole 4 with these respective values of thickness: 20, 21, and 24 μm...
2018: Colloid and Polymer Science
Qian Wang, Jiean Chen, Yong Huang
Cooperative catalysis combining a transition metal with an N-heterocyclic carbene is challenging due to strong binding of NHCs towards late transition metals. We report the first example of synergistic catalysis by a chiral NHC and a coordinatively unsaturated ruthenium compound. RuCl3 was found to mediate efficient aerobic oxidation of homoenolates generated from enals and the N-heterocyclic carbene. The resulting α,β-unsaturated acylazolium intermediate reacts selectively with 1,3-dicarbonyl compounds or ketones at either the β- or γ-carbon, yielding polysubstituted chiral lactones in high yield and with excellent enantioselectivity (up to 98 % yield, 94 % ee)...
July 5, 2018: Chemistry: a European Journal
Jing-Jing Meng, Zhan-Fang Hou, Er-Xun Zhang, Jie Dong, Xiao-di Liu, Ji-Zhao Xing, Jia-Zhen Liu
To identify the seasonal variation of dicarboxylic acids and related compounds in PM10 from Mt. Huangshan. PM10 samples were collected during the summer and winter of 2015, which were then analyzed for dicarboxylic acids, ketocarboxylic acids, and α -dicarbonyls. The results showed that oxalic acid(HOOC-COOH, C2 ) was the dominant species in the summer and winter months, followed by malonic acid(HOOC-CH2 -COOH, C3 ), and succinic acid[HOOC-(CH2 )2 -COOH, C4 ], being consistent with that in other high-altitude regions...
July 8, 2017: Huan Jing Ke Xue= Huanjing Kexue
Charalampos Triantis, Antonio Shegani, Christos Kiritsis, Myrto Ischyropoulou, Ioanna Roupa, Vassilis Psycharis, Catherine Raptopoulou, Patricia Kyprianidou, Maria Pelecanou, Ioannis Pirmettis, Minas S Papadopoulos
The synthesis and characterization of the dicarbonyl mixed ligand cis-[Re(CO)2 (quin)(cisc)(PPh3 )] complex, 4, where quin is the deprotonated quinaldic acid, cisc is cyclohexyl isocyanide, and PPh3 is triphenylphosphine, is presented. The synthesis of 4 proceeds in three steps. In the first, the intermediate fac-[Re(CO)3 (quin)(H2 O)] aqua complex 2 is generated from the fac-[NEt4 ]2 [Re(CO)3 Br3 ] precursor, together with the brominated products fac-[Re(CO)3 (quinH)(Br)] 1a and fac-[NEt4 ][Re(CO)3 (quin)(Br)] 1b, in low yield...
July 16, 2018: Inorganic Chemistry
Cong Wang, Rui-Hua Liu, Ming-Qing Tian, Xu-Hong Hu, Teck-Peng Loh
A radical-mediated oxidative cross-coupling of readily accessible α-alkylated styrenes with 1,3-dicarbonyl compounds utilizing a combination of Cu(OAc)2 and air as a catalytic system is described. Rather than requiring α-halocarbonyl compounds, this efficient approach enables direct installation of tertiary functionalized alkyl motifs to olefins with simple carbonyl derivatives. The novel protocol is characterized with high allylic selectivities via a competing β-H elimination. Both radical-clock and -trapping experiments provided clear-cut evidence for the intermediacy of an α-keto carbon-centered radical...
July 6, 2018: Organic Letters
Christoph Schneider, Marcel Schlegel, Peter Coburger
The rapid assembly of molecular complexity continues to be at the forefront of novel reaction development. In the pursuit of that goal, we herein report a novel Sc(OTf)3-catalyzed, one-pot multicomponent reaction, that furnishes complex multicyclic 2 pyrrolines with excellent overall yields and perfect diastereocontrol. This process is based on our previously established (2+2+1)-cycloannulation of in situ-generated 1-azaallyl cations, 1,3-dicarbonyls and primary amines. The newly formed and highly reactive aminal moiety is readily substituted with indoles and pyrroles both as external and internal p-nucleophiles to provide densely functionalized N-heterocycles with four new s-bonds and two vicinal quaternary stereogenic centers...
June 25, 2018: Chemistry: a European Journal
Sidra Islam, Abdul Rouf Mir, Minhal Abidi, Mohd Talha, Atif Zafar, Safia Habib, Moinuddin
The detection of autoantibodies generated against modified proteins that stimulate cellular and humoral immune response has developed a lot of interest in the recent years and a search for biomarkers for the early detection of diseases has increased. IgG protein has earned attention for its possible modifications under hyperglycaemic conditions in rheumatoid arthritis, wherein dicarbonyl stress has been reported to alter the structural integrity of the protein. This report suggests that the interaction of the methylglyoxal with the IgG has consequences in the autoimmunopathology of rheumatoid arthritis...
June 15, 2018: International Journal of Biological Macromolecules
N M O Arcanjo, C Luna, M S Madruga, M Estévez
Methylglyoxal (MGO) and glyoxal (GO) are attracting considerable attention because of their role in the onset of diabetes symptoms. Therefore, to comprehend the molecular fundamentals of their pathological actions is of the utmost importance. In this study, the molecular interactions between resveratrol (RES) and human serum albumin (HSA) and the ability of the stilbene to counteract the oxidative damage caused by pathological concentrations of MGO and GO to the human plasma protein, was assessed. The oxidation of Cys34 in HSA as well as the formation of specific protein semialdehydes AAS (α-aminoadipic), GGS (γ-glutamic) and the accumulation of Advanced Glycation End-products (AGEs) was investigated...
September 2018: Biochimica et Biophysica Acta
Bettina Ebert, Dieter Ebert, Katrin Koebsch, Edmund Maser, Michael Kisiela
Oxidative stress is a major source of reactive carbonyl compounds that can damage cellular macromolecules, leading to so-called carbonyl stress. Aside from endogenously formed carbonyls, including highly reactive short-chain aldehydes and diketones, air pollutants derived from diesel exhaust like 9,10-phenanthrenequinone (PQ) can amplify oxidative stress by redox cycling, causing tissue damage. Carbonyl reductases (CRs), which are inducible in response to ROS, represent a fundamental enzymatic defense mechanism against oxidative stress...
June 12, 2018: FEBS Journal
Klaudia Borysiuk, Monika Ostaszewska-Bugajska, Marie-Noëlle Vaultier, Marie-Paule Hasenfratz-Sauder, Bożena Szal
Nitrate (NO3 - ) and ammonium (NH4 + ) are prevalent nitrogen (N) sources for plants. Although NH4 + should be the preferred form of N from the energetic point of view, ammonium nutrition often exhibits adverse effects on plant physiological functions and induces an important growth-limiting stress referred as ammonium syndrome. The effective incorporation of NH4 + into amino acid structures requires high activity of the mitochondrial tricarboxylic acid cycle and the glycolytic pathway. An unavoidable consequence of glycolytic metabolism is the production of methylglyoxal (MG), which is very toxic and inhibits cell growth in all types of organisms...
2018: Frontiers in Plant Science
Pronab Kundu, Nitin Chattopadhyay
Photophysics of 9,9'-anthril have been investigated at room temperature and cryogen phase (77 K) exploiting steady state and time-resolved emission techniques together with quantum chemical calculations. Absorption spectra, emission spectra, and emission lifetimes of anthril have been recorded and analyzed in polar ethanol and nonpolar methylcyclohexane media. Both room temperature and cryogenic experiments reveal a single emission band upon excitation at the nπ* absorption band whereas on exciting the system at the ππ* band, dual emission bands have been observed...
June 28, 2018: Journal of Physical Chemistry. A
Rong Zhou, Honghui Zhang, Jialin Liu, Rongfang Liu, Wen-Chao Gao, Yan Qiao, Ruifeng Li
Herein, we report a chemoselective P(NMe2 )3 -mediated reductive epoxidation of α-dicarbonyl compounds such as isatins, α-keto esters, and α-diketones with aldehydes and ketones, leading to an efficient synthesis of a wide range of highly functionalized unsymmetrical epoxides in moderate to excellent yields and diastereoselectivities. The Kukhtin-Ramirez adduct, which is exclusively generated in situ from an α-dicarbonyl compound and P(NMe2 )3 , plays a key role in governing the chemoselectivity. It represents the first practical synthesis of unsymmetrical epoxides via direct reductive epoxidation of two different carbonyl electrophiles and also complements the existing methods of generating epoxides...
June 13, 2018: Journal of Organic Chemistry
Juliana M de Souza, Timothy J Brocksom, D Tyler McQuade, Kleber T de Oliveira
We have investigated the continuous flow photooxidation of several conjugated dienes and subsequent rearrangement using a practical and safe continuous-flow homemade engineered setup. End-to-end approaches involving endoperoxidation, Kornblum-DeLaMare rearrangement, and additional rearrangements are comprehensively detailed with optimization, scope, and scale-up to obtain useful hydroxyenones, furans, and 1,4-dicarbonyl building blocks.
June 7, 2018: Journal of Organic Chemistry
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