Read by QxMD icon Read

Journal of Organic Chemistry

Verónica Selva, Olatz Larrañaga, Luis M Castelló, Carmen Nájera, José M Sansano, Abel de Cozar
Diastereoselective multicomponent reaction of enantioenriched 4-nitroprolinates, obtained by enantiocatalyzed 1,3-dipolar cycloaddition (1,3-DC) of imino esters and nitroalkenes, with α,β-unsaturated aldehydes and electrophilic alkenes proceed with total periselectivity depending on the structure of the aldehyde employed. This process evolves through a [3+2] 1,3-DC when cinnamaldehyde is used in the presence of an azomethine ylide giving the corresponding highly substituted pyrrolizidines with endo-selectivity...
May 23, 2017: Journal of Organic Chemistry
Yingtang Ning, Yuko Otani, Tomohiko Ohwada
An experimental study of base-induced transformation reaction of 2-acyl-3-alkyl-2H-azirines to oxazoles indicated that a deprotonation-initiated mechanism is involved, in addition to nucleophilic addition to the imine functionality. Calculations suggested the participation of a ketenimine (ethenimine) intermediate generated by azirine ring opening of the carbanion intermediate formed by α-deprotonation of 2H-azirine. The ketenimine intermediate possessing methyl substituents at C(3) appears to be more stable than the tautomeric nitrile ylide which was proposed to be involved in photo-induced and pyrolysis reactions of 2-acyl-3-alkyl-2H-azirines to afford oxazoles...
May 23, 2017: Journal of Organic Chemistry
Djani Skalamera, Kata Mlinarić-Majerski, Irena Martin Kleiner, Marijeta Kralj, Jessy Oake, Peter Wan, Cornelia Bohne, Nikola Basaric
Anthrols 2-7 were synthesized and their photochemical reactivity investigated by irradiations in aq. CH3OH. Upon excitation with visible light (λ > 400 nm) in methanolic solutions they undergo photodehydration or photodeamination and deliver methyl ethers, most probably via quinone methides (QMs), with methanolysis quantum efficiencies ΦR = 0.02-0.3. Photophysical properties of 2-7 were determined by steady-state fluorescence and time-correlated single photon counting. Generally, anthrols 2-7 are highly fluorescent in aprotic solvents (ΦF = 0...
May 23, 2017: Journal of Organic Chemistry
Gino A DiLabio, Paola Franchi, Osvaldo Lanzalunga, Andrea Lapi, Fiorella Lucarini, Marco Lucarini, Marco Mazzonna, Viki Kumar Prasad, Barbara Ticconi
A kinetic study of the hydrogen atom transfer (HAT) reactions from a series of organic compounds to the quinolinimide-N-oxyl radical (QINO) has been carried out in CH3CN. The HAT rate constants are significantly higher than those observed with the phthalimide-N-oxyl radical (PINO) as a result of enthalpic and polar effects due to the presence of the N-heteroaromatic ring in QINO. The relevance of polar effects is supported by theoretical calculations carried out for the reactions of the two N-oxyl radicals with toluene which indicate that the HAT process is characterized by a significant degree of charge transfer enabled by the pi-stacking that occurs in the transition state structures between the toluene and the N-oxyl aromatic rings...
May 23, 2017: Journal of Organic Chemistry
Yangji Jiang, Yaping You, Wanrong Dong, Zhihong Peng, Yingjun Zhang, Delie An
A general and direct N-arylation of sulfonamides and NH-sulfoximines by sodium arylsulfinates through a desulfitative pathway was herein demonstrated. The reaction proceeded with catalytic loadings of Cu(II)-catalysts without any external ligands. And the novel arylation protocol featured for high efficiency (up to 93% yields) and good substituent tolerance (up to 53 examples). Moreover, a plausible reaction mechanism was also discussed.
May 23, 2017: Journal of Organic Chemistry
Thibaud Mabit, Aymeric Siard, Mathilde Pantin, Doumadé Zon, Laura Foulgoc, Drissa Sissouma, André Guingant, Monique Mathé-Allainmat, Jacques Lebreton, François Carreaux, Gilles Dujardin, Sylvain Collet
An efficient access for the synthesis of pluramycinones is described. Total syntheses of racemic γ-indomycinone and kidamycinone were achieved by means of two Diels-Alder reactions. A first Diels-Alder condensation followed by a Stille cross-coupling is used for the elaboration of the desired substituted dienes which will be involved in the second pericyclic reaction with juglone to construct the tetracyclic core of pluramycinones.
May 23, 2017: Journal of Organic Chemistry
Laetitia Schoepff, Lucas Kocher, Stéphanie Durot, Valérie Heitz
The synthesis of two flexible bis-porphyrin cages 3 and 4, incorporating respectively Zn(II) porphyrins and free-base porphyrins, is reported. In both cages, the four covalent linkers that bind the two porphyrins are functionalized with two 1,2,3-triazolyl ligands. These cages were characterized by NMR and HRMS, and for cage 3 incorporating 1,4-diazabicyclo[2.2.2]octane (DABCO), an X-ray crystallographic structure was obtained. Chemically induced conformational changes are studied and compared to those of two related cages with longer flexible linkers...
May 23, 2017: Journal of Organic Chemistry
Oskar Popik, Bibek Dhakal, David Crich
The synthesis of a legionaminic acid donor from N-acetyl neuraminic acid in fifteen steps and 19% overall yield is described. Activation of the adamantanyl thioglycoside in the donor with N-iodosuccinimide and trifluoromethanesulfonic anhydride in dichloromethane and acetonitrile at -78 degrees C in the presence of primary secondary and tertiary alcohols affords the corresponding glycosides in excellent yield and good to excellent equatorial selectivity. In particular coupling to the 4-OH of a suitably protected neuraminic acid derivative affords a disaccharide that closely resembles the glycosidic linikage in the polylegionaminic acid from the lipopolysaccharide of the Legionella pneumophila virulence factor...
May 22, 2017: Journal of Organic Chemistry
Shea Fern Lim, Benjamin Leigh Harris, George N Khairallah, Evan John Bieske, Philippe Maître, Gabriel da Silva, Brian D Adamson, Michael S Scholz, Neville J A Coughlan, Richard A J O'Hair, Michael Rathjen, Daniel Stares, Jonathan M White
Collision-induced dissociation mass spectrometry of the ammonium ions 4a and 4b results in the formation of the seleniranium ion 5, the structure and purity of which was verified using gas phase infra-red spectroscopy coupled to mass spectrometry, and gas phase ion-mobility measurements. Ion-molecule reactions between the ion 5 (m/z = 261) and cyclopentene, cyclohexene, cycloheptene and cyclooctene, resulted in the formation of the seleniranium ions 7 (m/z = 225), 6 (m/z = 239), 8 (m/z = 253), and 9 (m/z = 267) respectively...
May 22, 2017: Journal of Organic Chemistry
Ewout Ruysbergh, Kristof Van Hecke, Christian Victor Stevens, Norbert De Kimpe, Sven Mangelinckx
Several natural products containing a 1,4-oxazepane-2,5-dione-core are known. One example is serratin, isolated from Serratia marcescens. Due to the presence of a carboxylic amide, which has a preference for a trans-conformation, and the presence of a labile lactone in this core, many synthetic methodologies commonly used for the cyclization towards medium-sized heterocycles cannot be applied. As N-acyl amino acids without a third substituent at nitrogen failed to undergo ring-closure, several N-protecting groups were evaluated...
May 22, 2017: Journal of Organic Chemistry
Yongjun Liu, Guang Tian, Jingjing Li, Yan Qi, Yonghong Wen, Feng Du
The novel bis-addition of benzaldehydes to acrylates or maleates was achieved by the direct use of samarium metal with the assistance of CuI under mild conditions under dry air, and the useful 2-hydroxylalkyl-γ-butyrolactons and lignan derivatives were thus constructed with high efficiency. The key factors that influence the reaction efficiency were investigated. The use of potassium iodide and molecular sieves as additives can improve the reaction efficiency remarkably.
May 22, 2017: Journal of Organic Chemistry
Megha Balha, Buddhadeb Mondal, Subas Chandra Sahoo, Subhas Chandra Pan
The first highly enantioselective organocatalytic reaction employing 2-hydroxyacetophenones has been disclosed, namely Michael-hemiacetalization reaction of 2-hydroxyacetophenones with enals. The combination of a primary amine and a secondary amine catalyst was found to be the best choice for this methodology. The products of this reaction were obtained in high enantio- and diasteroselectivities and have been converted to a variety of biologically important γ-butyrolactones.
May 19, 2017: Journal of Organic Chemistry
Stuart C D Kennington, Mònica Ferré, Juan M Romo, Pedro Romea, Fèlix Urpí, Mercè Font-Bardia
Direct nickel-catalyzed alkylation of chiral (N)-acyl-4-isopropyl-1,3-thiazolidine-2- thiones using a commercially available nickel(II) complex, (Me3P)2NiCl2, has been developed for tropylium and trityl tetrafluoroborate salts. The reaction provides a single diastereomer of the corresponding adducts in good to high yields, which, in turn, can be easily converted into a wide array of enantiomerically pure compounds that are difficult to obtain by other asymmetric procedures.
May 19, 2017: Journal of Organic Chemistry
Chun-Hua Chen, Qing-Qing Liu, Xiao-Pan Ma, Yu Feng, Cui Liang, Cheng-Xue Pan, Gui-Fa Su, Dong-Liang Mo
A copper-catalyzed selective cross-coupling reaction of 3-(hydroxyimino)indolin-2-ones with alkenyl boronic acids to access (E)-N-vinyl oxindole nitrones has been achieved under mild conditions. The studies showed that catalytic copper salt selectively gave mono N-vinylation products while 2.0 equiv of copper salt provided double N-vinylation products. The control experiments revealed that the carbonyl group in 3-(hydroxyimino)indolin-2-one played important roles on N-vinylation. Furthermore, the prepared N-vinyl oxindole nitrones could be converted to spirooxindoles in good yields under thermal conditions...
May 19, 2017: Journal of Organic Chemistry
Jessica A Griswold, Matthew A Horwitz, Leslie V Leiva, Jeffrey S Johnson
No abstract text is available yet for this article.
May 19, 2017: Journal of Organic Chemistry
Hiromu Saito, Akira Uchida, Soichiro Watanabe
Three-bladed propeller-shaped triple [5]helicene was synthesized using eliminative and oxidative photocyclization reactions, which proceeded in 37 and 63% yields, respectively. Chromatographic purification gave a mixture of diastereomers, and the PPM and PMM isomers were gradually converted to the thermodynamically more stable PPP and MMM isomers at room temperature. The activation parameters for the racemization of the PPP and MMM isomers were determined, and the structure of the triple [5]helicene was determined by X-ray crystallographic analysis...
May 19, 2017: Journal of Organic Chemistry
Dnyaneshwar Nilkanth Garad, Amol B Viveki, Santosh B Mhaske
The Pd-catalyzed quinazolinone-directed regioselective mono-arylation of aromatic rings by C-H bond activation is developed. A broad substrate scope is demonstrated for both quinazolinone as well as diaryliodonium triflates. Use of base was found to be crucial for this transformation, unlike the known nitrogen-directed arylations. All the novel quinazolinones of biological interest were synthesised by using operationally simple Pd(II)-catalyzed arylation reaction.
May 19, 2017: Journal of Organic Chemistry
Lisi He, Xinkan Yang, Gavin Chit Tsui
A domino hydroboration/trifluoromethylation (formal hydrotrifluoromethylation) of alkynes using the fluoroform-derived [CuCF3] reagent is achieved. Synthetically useful (E)-alkenyl-CF3 building blocks and 1,1-bis(trifluoromethyl)- substituted alkenes can be prepared under ambient conditions in one-pot/one-step from alkynes. The ultimate source of CF3 is the inexpensive industrial waste fluoroform.
May 19, 2017: Journal of Organic Chemistry
Rong-Rong Zhou, Qun Cai, Deng-Kui Li, Shi-Yi Zhuang, Yan-Dong Wu, An-Xin Wu
An acid-promoted multicomponent reaction for the synthesis of diverse fully substituted oxazole derivatives from simple and readily available arylglyoxal monohydrates, nitriles and various C-nucleophiles has been developed. This protocol features wide functional group diversity which is capable of installing 4-hydroxycoumarin, 2-naphthol and 1,3-cyclohexanedione motifs to oxazoles. Mechanistic analysis indicates that a classical Robinson-Gabriel reaction served as the key step for this tandem transformation...
May 19, 2017: Journal of Organic Chemistry
Chin-Chau Chen, Man-Yun Wu, Hsing-Yin Chen, Ming-Jung Wu
The halogen-mediated cyclization reaction of aryldiynes to produce halogenated indeno[1,2,-c]chromene derivatives is described. Treatment of aryldiynes 1 with one equivalent of iodine gave iodinated indeno[1,2,-c]chromenes 3 in good chemical yields. When two equivalents of iodine were employed into the reaction mixture, the dimmer 9 was obtained as the major products. On the other hand, reaction of two equivalents of CuBr2 with compounds 1 gave the brominated indeno[1,2,-c]chromenes 4. The DFT calculation on iodine-mediated cyclization reactions for the molecules bearing methoxyl, carboxylate, amine and sulfide were carried out to understand how the substituent could affect the mode of cyclization pathway...
May 19, 2017: Journal of Organic Chemistry
Fetch more papers »
Fetching more papers... Fetching...
Read by QxMD. Sign in or create an account to discover new knowledge that matter to you.
Remove bar
Read by QxMD icon Read

Search Tips

Use Boolean operators: AND/OR

diabetic AND foot
diabetes OR diabetic

Exclude a word using the 'minus' sign

Virchow -triad

Use Parentheses

water AND (cup OR glass)

Add an asterisk (*) at end of a word to include word stems

Neuro* will search for Neurology, Neuroscientist, Neurological, and so on

Use quotes to search for an exact phrase

"primary prevention of cancer"
(heart or cardiac or cardio*) AND arrest -"American Heart Association"