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Journal of Organic Chemistry

Abhijit Mal, Masthanvali Sayyad, Imtiyaz Ahmad Wani, Manas K Ghorai
A highly enantioselective synthetic route to hexahydropyrrolo[2,3-b]indoles via Lewis acid-catalyzed SN2-type ring opening of activated aziridines with indoles having substitutions at 3- and other positions followed by cyclization in a domino fashion has been developed. Hexahydropyrrolo[2,3-b]indoles have been detosylated in the same pot to afford the corresponding products with free NH group in excellent yields (up to 95%) and enantioselectivity (up to >99%).
October 19, 2016: Journal of Organic Chemistry
Mariateresa Giustiniano, Sveva Pelliccia, Ubaldina Galli, Jussara Amato, Fabio Travagin, Ettore Novellino, Gian Cesare Tron
Old multicomponent reactions are still a source of inspiration for discovering novel combinations of three or more reactants. A simple idea is to replace one of the educts of a known multicomponent reaction with another functional group and still able to mimic the same reactivity. Following this line of thought, we report a three-component reaction, in which isocyanides are able to open the epoxide-intermediate of the Bargellini reaction affording 3-carboxamido-isobutyric acids in yield of 47 to 95 %.
October 18, 2016: Journal of Organic Chemistry
Weiqiang Chen, Weili An, Yongjian Wang, Ao Yu
The detailed mechanism of the cyanide catalyzed synthesis of benzoxazole from 2-aminophenol and benzaldehyde was investigated in depth using Density Functional Theory (DFT). The metal-free aerobic oxidative process as well as the dehydrogenation detail was examined and described. Cyanide anion was proved to assist the oxygen atoms to undergo an aerobic dehydrogenation rather than direct cyclization which was predicted according to Baldwin's 5-exo-tet rule. The dehydrogenation pathway was thermodynamically favored over cyclization with an activation energy difference of 24...
October 18, 2016: Journal of Organic Chemistry
Yohei Okada, Masae Sugai, Kazuhiro Chiba
Fluorophores with emission wavelengths that shift depending on their hydrogen-bonding microenvironment in water would be fascinating tools for the study of biological events. Herein, we describe the design and synthesis of a series of water-soluble solvatochromic fluorophores, 2,5-bis(oligoethylene glycol)oxybenzaldehydes (8-11) and 2,5-bis(oligoethylene glycol)oxy-1,4-dibenzaldehydes (14-17), based on a push-pull strategy. Unlike typical examples in this class of fluorophores, the fluorescence properties of these compounds are independent of solvent polarity and become fluorescent upon intermolecular hydrogen-bonding, exhibiting high quantum yields (up to φ = 0...
October 18, 2016: Journal of Organic Chemistry
Varsha R Jumde, Niek N H M Eisink, Martin D Witte, Adriaan J Minnaard
Palladium catalysed oxidation is able to single out the secondary hydroxyl group at C3 in glucose, circumventing the more readily accessible hydroxyl at C6 and the more reactive anomeric hydroxyl. Oxidation followed by reduction results in either allose or allitol, rare sugars that are important in biotechnology. Also N-acetyl glucosamine is selectively oxidized at C3. These results demonstrate that glucose and N-acetyl glucosamine, the most readily available chiral building blocks, can be versatile substrates in homogeneous catalysis...
October 18, 2016: Journal of Organic Chemistry
Katy Schäfer, Heiko Ihmels, Cornelia Bohne, Karolina Papera Valente, Anton Granzhan
It is shown by photometric and fluorimetric analysis, along with supporting theoretical calculations, that hydroxy-substituted benzo[b]quinolizinium derivatives display the characteristic features of organic photoacids. Specifically, the experimental and theoretical results confirm the strong acidity of these compounds in the excited state (pKa* < 0). The combination of the prototropic properties of the 8- and 9-hydroxybenzo[b]quinolizinium with the particular solvent-solute interactions of the excited acid and its conjugate base leads to a pronounced fluorosolvatochromism...
October 18, 2016: Journal of Organic Chemistry
William Herbert Miles, Michael J Robinson, Samantha G Lessard, Dasan M Thamattoor
Several naphthalene compounds containing a methyl group in a 1,8-relationship to a metal-complexed phenyl ring bearing various substituents have been synthesized. The through-space shielding effects of the phenyl ring, as a function of substituent and complexing metal species, were monitored by observing the 1H NMR signal of the methyl group located in the shielding zone of the ring. In all cases, the methyl signal was slightly more downfield in the complexes than in the uncomplexed analogs. A comparison of available crystal structures, however, show that the phenyl ring is slightly closer to the naphthyl methyl group in the complexes than in their metal-free counterparts...
October 18, 2016: Journal of Organic Chemistry
Yarra Venkatesh, Yetirajam Rajesh, Sambath Karthik, Chetan Anabur C, Mahitosh Mandal, Avijit Jana, N D Pradeep Singh
A new fluorescent photoremovable protecting group (FPRPG) based on acetylcarbazole framework has been explored for the first time release of single and dual (similar or different) substrates from single chromophore. Mechanistic studies of the photorelease process revealed that photorelease of two (similar or different) substrates from acetyl carbazole proceeds via a stepwise pathway. Further, we constructed photoresponsive dual drug delivery system (DDS) to release of two different anticancer drugs (Caffeic acid and Chlorambucil 1 equivalent each)...
October 18, 2016: Journal of Organic Chemistry
Xiang Zhang, Guangshuai Zhou, Yong Zhang, Daisy Zhang-Negrerie, Yunfei Du, Kang Zhao
An efficient ring-contraction reaction of isochromeno[4,3-b] indol-5(11H)-ones via a nucleophile-induced disproportionation-spirocyclization cascade process has been developed under mild conditions. The process realized the conversion of isochromeno[4,3-b]indol-5(11H)-ones into N-unsubstituted spiro[indoline-2,1'-isobenzofuran]-3,3'-diones and spiro[indoline-2,1'-isoindoline]-3,3'-diones in the absence of a transition-metal catalyst or oxidant. Gram-scale reaction further demonstrated the practicability of the protocol...
October 18, 2016: Journal of Organic Chemistry
Bernd Schmidt, Felix Wolf, Christopher Ehlert
alpha-Methylene-gamma-butyrolactone and alpha-methylene-delta-valerolactone undergo Pd-catalyzed Matsuda-Heck couplings with arene diazonium salts to alpha-benzyl butenolides or pentenolides, respectively, or to alpha-benzylidene lactones. The observed regioselectivity is strongly ring size dependent, with six-membered rings giving exclusively alpha-benzyl pentenolides, whereas the fivemembered alpha-methylene lactone reacts to mixtures of regioisomers with a high proportion of E-alpha-benzylidene-gamma-butyrolactones...
October 17, 2016: Journal of Organic Chemistry
Jing-Kai Huang, Ying-Chieh Wong, Tzu-Ting Kao, Chen-Tso Tseng, Kak-Shan Shia
A new NHPI/Co(II)-catalyzed protocol, mechanistically involving a sequence of alpha-hydrogen abstraction, 5-exo-dig cyclization, oxygen capture, hydrogen transfer and 1,4-dehydration, has been developed to facilitate aerobic oxidation of aryl-, silyl- and alkyl-capped alkynyl alpha-cyano alkanone systems, respectively, to the corresponding highly functionalized products in an effective manner, thus turning this novel chain reaction, originally occurring spontaneously in low yields, into a practical methodology...
October 17, 2016: Journal of Organic Chemistry
Michael J Houghton, David B Collum
Enolization of O-methyl hydroxamic acids (Weinreb amides) in tetrahydrofuran solution with lithium diisopropylamide affords predominantly tetrameric enolates. Aryl substituents on the enolates promote deaggregation. The aggregation states are assigned by using the method of continuous variation in conjunction with (6)Li NMR spectroscopy. Decoalescence of the tetramer resonance below -100 °C shows considerable spectral complexity attributed to isomerism of the methoxy-based chelates. Density functional theory calculations were used to examine the consequences of the bite angle of five-membered chelates in cubic tetramers and resulting solvation numbers that were higher than anticipated...
October 17, 2016: Journal of Organic Chemistry
Pavel Golubev, Ekaterina A Karpova, Alena S Pankova, Mariia Sorokina, Mikhail A Kuznetsov
Condensation of enynones readily available from cheap starting material with pyrazolamines provides easy access to fluorescent 7-(trimethylsilylethynyl)pyrazolo[1,5-a]pyrimidines. The reaction is straightforward, does not require the use of any additional reagents or catalysts and can be performed without inert atmosphere. Various substituents and functional groups in both enynone and pyrazolamine are tolerated. The presented method features full regioselectivity, high isolated yields and simplicity of both set-up and product purification...
October 17, 2016: Journal of Organic Chemistry
Scott W Krabbe, Vincent S Chan, Thaddeus S Franczyk, Shashank Shekhar, José G Napolitano, Carmina A Presto, Justin A Simanis
A Cu-catalyzed synthesis of amides from alcohols and secondary amines using the oxygen in air as the terminal oxidant has been developed. The methodology is operationally simple requiring no high pressure equipment or potentially explosive O2 balloons. The commercially available, non-precious metal catalyst, Cu(phen)Cl2, in conjunction with di-tert-butyl hydrazine dicarboxylate and an inorganic base provides a variety of benzamides in moderate to excellent yields. The pKa of amine conjugate acid and electronics of alcohol were shown to impact the selection of base for optimal reactivity...
October 14, 2016: Journal of Organic Chemistry
Sidney Malik Wilkerson-Hill, Shota Sawano, Richmond Sarpong
Herein we describe the first approach to 3-oxidopyrylium ions from a linear precursor. Heating bis(1-cyanovinyl acetate) in the presence of a trace amount of pyridinium p-toluenesulfonate results in a series of acyl group transfers and an intramolecular cyclization event to form a 3-oxidopyrylium ion that can be trapped by reaction with several dipolarophiles. When treated with dienes, the result is a sequential [5+2]/[4+2] cycloaddition reaction that provides sp3-rich products of high molecular complexity.
October 14, 2016: Journal of Organic Chemistry
José Gomes, Christophe Daeppen, Raphael Liffert, Joel Roesslein, Elias Kaufmann, Annakaisa Heikinheimo, Markus Neuburger, Karl Gademann
Synthetic studies towards highly oxygenated seco-prezizaane sesquiterpenes are reported, which culminated in a formal total synthesis of the neurotrophic agent (-)-jiadifenolide. For the construction of the tricyclic core structure, an unusual intramolecular and diastereoselective Nozaki-Hiyama-Kishi reaction involving a ketone as electrophilic coupling partner was developed. In addition, synthetic approaches towards the related natural product (2R)-hydroxynorneomajucin, featuring a Mn-mediated radical cyclization for the tricycle assembly and a regioselective OH-directed C-H activation are presented...
October 14, 2016: Journal of Organic Chemistry
Olivier Galangau, Stephanie Delbaere, Nicolas Ratel-Ramond, Gwenael Rapenne, Ruiji Li, Jan Patrick Dela Cruz Calupitan, Takuya Nakashima, Tsuyoshi Kawai
In this manuscript, we present a novel concept for "smarter" photo-labile organic compounds combining not one but two caged functions. As proof of principle, this diarylethene-based compound possesses two inhibited chemical groups (OMe and OAc) and its efficient release in different solvents is reported. In low to medium polar media, both MeOH and AcOH are released, with a slight preferential uncaging of AcOH except in 1,4-dioxane where MeOH is preferentially released. On the contrary, DMSO or DMF render AcOH releasing strongly dominating...
October 14, 2016: Journal of Organic Chemistry
Christopher J Brassard, Xiaoguang Zhang, Christopher R Brewer, Peiye Liu, Ronald J Clark, Lei Zhu
Copper(II) acetate under aerobic conditions catalyzes the formation of 5,5'-bis(1,2,3-triazole)s (5,5'-bistriazoles) from organic azides and terminal alkynes. This reaction is an oxidative extension of the widely used copper-catalyzed azide-alkyne 'click' cycloaddition. The inclusions of potassium carbonate as an additive and methanol or ethanol as the solvent, and in most instances an atmosphere of dioxygen, promote the oxidative reaction to afford 5,5'-bistriazole at the expanse of 5-protio-1,2,3-triazole (5-protiotriazole)...
October 14, 2016: Journal of Organic Chemistry
Annika Ries, Rajesh Kumar, Chenguang Lou, Tamer Kosbar, Empar Vengut-Climent, Per Trolle Jørgensen, Juan C Morales, Jesper Wengel
Galactose-modified thymidine, LNA-T and 2'-amino-LNA-T nucleosides were synthesized, converted into the corresponding phosphoramidite derivatives and introduced into short oligonucleotides. Compared to the unmodified control strands, the galactose-modified oligonucleotides in general, and the N2'-functionalized 2'-amino-LNA derivatives in particular, showed improved duplex thermal stability against DNA and RNA complements and increased ability to discriminate mismatches. In addition, especially the 2'-amino-LNA-T derivatives induced remarkable 3'-exonucleolytic stability...
October 13, 2016: Journal of Organic Chemistry
Starr Dostie, Michel Prévost, Philippe Mochirian, Kashif Tanveer, Nicholas Andrella, Ariana Rostami, Guillaume Tambutet, Yvan Guindon
Nucleoside analogues bearing a fluorine in the C2'-position have been synthesized by SN2-like cyclizations of acyclic thioaminal precursors. This strategy provides access to two scaffolds, D-1',2'-cis thiofuranosides and D-1',2'-trans furanosides, that are difficult to generate using the standard approach for nucleoside synthesis. The addition of silylated nucleobases onto model C2-fluorinated dithioacetal substrates resulted in 1,2-syn diastereoselectivity which is consistent with the C2-F and S-alkyl moiety being in close proximity...
October 13, 2016: Journal of Organic Chemistry
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