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Journal of Organic Chemistry

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https://www.readbyqxmd.com/read/28431208/copper-catalyzed-chemoselective-and-enantioselective-friedel-crafts-1-2-addition-of-pyrrole-with-%C3%AE-%C3%AE-unsaturated-%C3%AE-ketoesters
#1
Jianan Sun, Yanbin Hu, Yanan Li, Sheng Zhang, Zhenggen Zha, Zhiyong Wang
A Friedel-Crafts alkylation of pyrrole was developed to afford the β,γ-unsaturated α-hydroxy esters bearing quaternary stereogenic center with good enantioselectivities and yields. This protocol represents the first report of 1,2-addition of Friedel-Crafts alkylation of pyrrole to β,γ-unsaturated α-ketoesters.
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28431207/syntheses-of-chroman-2-ones-and-%C3%AE-amino-acids-through-a-diastereoselective-domino-reaction
#2
D Balaji Chandrasekhar, Shwu-Chen Tsay, Tapan K Pradhan, Jih Ru Hwu
Many 3-aminochroman-2-ones and β,β-diarylalanines exhibit significant biological activities. A new method was thus developed for the syntheses of these compounds with high efficiency and diastereoselectivity. First, treatment of various phenols with Erlenmeyer-Plochl (Z)-azlactones and AlCl3 in toluene produced the desired cis-3-aminochroman-2-ones in 65-90% yields under kinetic control. This coupling reaction involved a domino process of Friedel-Crafts alkylation, 1,4-AlCl3 shift, transesterification, and protodealumination in a "single-flask...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28430441/oxygen-bridged-diphenylnaphthylamine-as-a-scaffold-for-full-color-circularly-polarized-luminescent-materials
#3
Hidetaka Nishimura, Kazuo Tanaka, Yasuhiro Morisaki, Yoshiki Chujo, Atsushi Wakamiya, Yasujiro Murata
An oxygen-bridged diphenylnaphthylamine with a helical shape was designed and synthesized as a key scaffold for circularly polarized luminescent (CPL) materials. The introduction of electron-withdrawing groups, such as formyl and 2,2-dicyanovinyl substituents at the naphthyl moiety in this skeleton effectively decreases the LUMO level and thus allows a tuning of the band-gap. The prepared model compounds exhibit intense CPL signals with a dissymmetry factor (g value) of 10-3 both in CH2Cl2 solutions and in the solid states...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28430439/molecular-organization-of-2-1-3-benzothiadiazoles-in-the-solid-state
#4
Sophie Langis-Barsetti, Thierry Maris, James D Wuest
Derivatives of 2,1,3-benzothiadiazole (1) are widely used in many areas of science and are particularly valuable as components of active layers in various thin-film optoelectronic devices. Even more effective benzothiadiazoles are likely to result if a deeper understanding of their preferred patterns of molecular association can be acquired. To provide new insight, we have analyzed the structures of compounds in which multiple benzothiadiazole units are attached to well-defined planar and nonplanar molecular cores...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28429946/ag-catalyzed-intramolecular-sequential-vicinal-diamination-of-alkynes-with-isocyanates-synthesis-of-fused-indole-cyclic-urea-derivatives
#5
Manda Rajesh, Surendra Puri, Ruchir Kant, Maddi Sridhar Reddy
A formal intramolecular vicinal 1,2-diamination of alkynes is achieved for the synthesis of indole-cyclic urea fused derivatives through double cyclization process from readily available aminophenyl propargyl alcohols. This sequential triple C-N bond construction event was possible using isocyanate as urea precursor and Ag(I) catalyst as alkyne activating agent. Control experiments reveal that the cyclization followed by 1,3-allylic amino dehydroxylation is preceded by urea formation.
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28429945/copper-catalyzed-oxidative-cyclization-of-2-amino-azaarenes-with-lignin-models-synthesis-of-3-phenoxy-imidazo-heterocycles
#6
Jian Zhang, Xiunan Lu, Tingyan Li, Shanlu Wang, Guofu Zhong
A catalytic oxidative cyclization of 2-aminopyridines or 2-aminobenzothiazole with 2-phenoxyacetophenones (a kind of lignin platform compounds) was developed, efficiently providing valuable 3-phenoxy imidazo[1,2-a]pyridines or 3-phenoxy benzo[d]imidazo[2,1-b]thiazoles. The reaction was realized under oxygen by simply using inexpensive CuI as the catalyst.
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28429590/palladium-catalyzed-n-2-aminophenyl-acetamide-assisted-ortho-arylation-of-substituted-benzamides-application-to-the-synthesis-of-urolithins-b-m6-and-m7
#7
M Damoder Reddy, Alexandra N Blanton, E Blake Watkins
Pd-catalyzed, selective, monoarylation of ortho-C-H bonds of various benzamides with aryl/heteroaryl iodides has been realized using N-(2-aminophenyl)acetamide (APA) as a new bidentate directing group for the first time. The reaction was tolerant of a wide range of functional groups, and a variety of biaryl amide derivatives were successfully prepared in good to moderate yield. The utilization of N-(2-aminophenyl)acetamide as a novel directing group, Mn(OAc)2 as a co-oxidant (silver free reaction conditions), and absolute ortho-monoaryl selectivity are notable features of this reaction...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28427259/copper-catalyzed-diaryl-ether-formation-from-hetero-aryl-halides-at-low-catalytic-loadings
#8
Yuntong Zhai, Xiaofei Chen, Wei Zhou, Mengyang Fan, Yisheng Lai, Dawei Ma
Diaryl formation is achieved by coupling phenols and (hetero)aryl halides under the catalysis of CuI/N,N'-bis(2-phenylphenyl) oxalamide (BPPO) or CuI/ N-(2-phenylphenyl)-N'-benzyl oxalamide (PPBO) at 90 degrees C using DMF or MeCN as the solvent. Only 0.2-2 mol % CuI and ligand are required for completer conversion, which represents the lowest catalytic loadings for a general Cu/ligand-catalyzed diaryl ether formation.
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28414461/a-tetraphenylethene-naphthyridine-based-aiegen-tpen-with-dual-mechanochromic-and-chemosensing-properties
#9
Shahida Umar, Ajay Kumar Jha, Deepak Purohit, Atul Goel
Synthesis of new tetraphenylethene (TPE) conjugates via an innocuous route led to the revelation of a unique TPE-based aggregation-induced emissive fluorogen 3 (TPEN), which showed an interesting mechanochromic property when the emission was changed from blue to green upon grinding and green to blue upon fuming. The mechanochromic property of TPEN has been explored to prepare ink-free rewritable paper for security documentation. A detailed photophysical investigation of the TPE-naphthyridine scaffold led to the discovery of its high sensitivity to silver ions (Ag(+)) over other metal ions with a detection limit of 0...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28407711/using-ring-strain-to-control-4%C3%AF-electrocyclization-reactions-torquoselectivity-in-ring-closing-of-medium-ring-dienes-and-ring-opening-of-bicyclic-cyclobutenes
#10
Byron A Boon, Aaron G Green, Peng Liu, K N Houk, Craig A Merlic
Syntheses of strained cyclic dienes were accomplished via palladium(II)-catalyzed oxidative cyclizations of terminal bis(vinylboronate esters). The reactions generate strained (E,E)-1,3-dienes that undergo spontaneous 4π-electrocyclizations to form bicyclic cyclobutenes. Formation of the cyclobutenes is driven by the strain in the medium-ring (E,E)-1,3-diene intermediate. Thermal ring openings of the cyclobutenes give (Z,Z)-1,3-diene products, again for thermodynamic reasons. DFT calculations verified the thermodynamic versus kinetic control of the reactions, and kinetic studies are in excellent agreement with the calculated energy changes...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28406031/iodine-catalyzed-c-n-bond-formation-synthesis-of-3-aminoquinoxalinones-under-ambient-conditions
#11
Abhishek Gupta, Mahesh Subhashrao Deshmukh, Nidhi Jain
A metal-free cross-dehydrogenative coupling between quinoxalinones (sp(2) C-H) and amines (N-H) in the presence of catalytic iodine is reported. The reaction yields 3-aminoquinoxalinones in moderate to high yields under ambient conditions in dioxane as solvent and aqueous tert-butyl hydroperoxide (TBHP) as the terminal oxidant. The reaction is highly versatile and exhibits good functional group tolerance with a range of primary and secondary amines. It provides a practical access to pharmaceutically active 3-aminoquinoxalinone derivatives...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28398045/conformational-effects-through-hydrogen-bonding-in-a-constrained-%C3%AE-peptide-template-from-intraresidue-seven-membered-rings-to-a-gel-forming-sheet-structure
#12
Hawraà Awada, Claire M Grison, Florence Charnay-Pouget, Jean-Pierre Baltaze, François Brisset, Régis Guillot, Sylvie Robin, Ali Hachem, Nada Jaber, Daoud Naoufal, Ogaritte Yazbeck, David J Aitken
A series of three short oligomers (di-, tri-, and tetramers) of cis-2-(aminomethyl)cyclobutane carboxylic acid, a γ-amino acid featuring a cyclobutane ring constraint, were prepared, and their conformational behavior was examined spectroscopically and by molecular modeling. In dilute solutions, these peptides showed a number of low-energy conformers, including ribbonlike structures pleated around a rarely observed series of intramolecular seven-membered hydrogen bonds. In more concentrated solutions, these interactions defer to an organized supramolecular assembly, leading to thermoreversible organogel formation notably for the tripeptide, which produced fibrillar xerogels...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28394594/synthesis-of-geometrically-well-defined-covalent-acene-dimers-for-mechanistic-exploration-of-singlet-fission
#13
Thomas J Carey, Jamie L Snyder, Ethan G Miller, Tarek Sammakia, Niels H Damrauer
We report the first synthesis of norbornyl-bridged acene dimers (2 and 3) with well-defined and controlled spatial relationships between the acene chromophore subunits. We employ a modular 2-D strategy wherein the central module, common to all our compounds, is a norbornyl moiety. The acenes are attached to this module using the Diels-Alder reaction, which also forms one of the acene rings. Manipulation of the Diels-Alder adducts provides the desired geometrically defined bis-acenes. The modular nature of this synthesis affords flexibility and allows for the preparation of a variety of acene dimers, including functionalized tetracene dimers...
April 21, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28426214/calix-5-arene-through-the-annulus-threading-of-dialkylammonium-guests-weakly-paired-to-the-tfpb-anion
#14
Margherita De Rosa, Carmen Talotta, Carmine Gaeta, Annunziata Soriente, Placido Neri, Sebastiano Pappalardo, Giuseppe Gattuso, Anna Notti, Melchiorre F Parisi, Ilenia Pisagatti
The through-the-annulus threading of calix[5]arene penta-O-ethers by dialkylammonium cations coupled to the loosely coordinating superweak TFPB- anion has been successfully accomplished. 1H NMR titration data show that the preorganization of the calix[5]arene scaffold leads to great thermodynamic stability of the pseudorotaxane complexes as well as to a favorable kinetic of threading. Accordingly, calix[5]arene 1c, bearing tert-butyl groups at the wide rim, was threaded by all the cations under study (with the exception of the dibenzylammonium 2b+) more tightly than the other derivatives under investigation (Kas up to 2...
April 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28426212/construction-of-%C3%AE-trifluoromethyl-enol-ether-via-base-promoted-c-o-coupling-and-rearrangement-of-hydrogen-atom
#15
Kun Dai, Kuan Wang, Yang Li, Jian-Gang Chen, Zhong-Wen Liu, Jian Lu, Zhao-Tie Liu
A novel, high-efficiency and high-selectivity construction of β-trifluoromethyl enol ether via base-induced/promoted C-O coupling of trifluoromethylated vinyl chloride and phenols is presented with a broad substrate scope. The reaction mechanism, especially the significantly high selectivity, was excavated and understood via DFT calculation, and is well supported by the experimental observation.
April 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28414466/enantioselective-synthesis-of-chiral-%C3%AE-azido-and-%C3%AE-aryloxy-quaternary-stereogenic-centers-via-the-phase-transfer-catalyzed-%C3%AE-alkylation-of-%C3%AE-bromomalonates-followed-by-sn2-substitution
#16
Doyoung Kim, Min Woo Ha, Suckchang Hong, Cheonhyoung Park, Byungsoo Kim, Jewon Yang, Hyeung-Geun Park
A new efficient synthetic method for chiral α-azido-α-alkylmalonates and α-aryloxy-α-alkylmalonates was developed. The enantioselective α-alkylation of diphenylmethyl tert-butyl α-bromomalonate under phase-transfer catalytic conditions [(S,S)-3,4,5-trifluorophenyl-NAS bromide, 50% KOH, toluene, and -40 °C) provided the corresponding α-bromo-α-alkylmalonates in high chemical yields (≤98%) and high optical yields (≤99% ee). The resulting α-alkylated products were converted to α-azido-α-alkylmalonates (≤96%, ≤97% ee) and α-aryloxy-α-alkylmalonates (≤79%, ≤93% ee) by SN2 substitution with sodium azide and aryloxides, respectively...
April 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28414446/radical-decarboxylation-annulation-of-acrylamides-with-aliphatic-acyl-peroxides
#17
Changduo Pan, Yu Fu, Qingting Ni, Jin-Tao Yu
A radical decarboxylation/annulation of acrylamides with aliphatic acyl peroxides was developed, giving a series of linear alkylated oxindoles in moderate to good yields. The reaction used aliphatic acyl peroxides as the linear alkyl radical source and tolerated a broad scope of substrates under metal-free conditions, offering a simple and efficient approach toward alkylated oxindoles.
April 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28407713/bifunctional-quaternary-ammonium-salts-catalyzed-stereoselective-conjugate-addition-of-oxindoles-to-electron-deficient-%C3%AE-haloalkenes
#18
Qiaowen Jin, Changwu Zheng, Gang Zhao, Gang Zou
A highly Z-selective asymmetric conjugate addition of 3-substituted oxindoles to β-haloalkene ketones/esters catalyzed by readily available chiral bifunctional quaternary ammonium salts is reported. This reaction provides efficient access to a range of 2-oxoindole derivatives bearing a thermodynamically unstable Z-olefin structure and a chiral quaternary carbon center in high yields (up to 90%) and with good to high stereoselectivities (up to >19:1 Z/E and 91% ee) under mild conditions.
April 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28406011/palladium-catalyzed-oxidative-carbonylation-of-aryl-hydrazines-with-co-and-o2-at-atmospheric-pressure
#19
Yongliang Tu, Lin Yuan, Tao Wang, Changliu Wang, Jiamei Ke, Junfeng Zhao
Palladium-catalyzed aerobic oxidative aminocarbonylation and alkoxycarbonylation reactions with aryl hydrazines as coupling partners have been developed. The oxidative carbonylation of aryl hydrazines proceeded smoothly at atmospheric pressure CO, employing molecular oxygen as the terminal oxidant. The only byproducts were nitrogen gas and water for both reactions. Notably, no double carbonylation was detected. Furthermore, aryl-halogen bonds, which are normally reactive in conventional Pd-catalyzed carbonylation reactions, remained intact...
April 20, 2017: Journal of Organic Chemistry
https://www.readbyqxmd.com/read/28402642/pd-boron-catalyzed-one-carbon-isomerization-of-olefins-water-assisted-process-at-room-temperature
#20
Devi Prasan Ojha, Karthik Gadde, Kandikere Ramaiah Prabhu
A palladium-boronate/borane-system -catalyzed isomerization of olefins has been uncovered. An efficient catalytic combination of [Pd(OAc)2]3-boronate-PCy3-enabled olefin isomerization at 80 °C has been investigated. Addition of water to the reaction showed a remarkable improvement and the isomerization occurred at ambient temperature. These catalytic systems function efficiently for the isomerization of functionalized as well as unfunctionalized olefins. The catalytic conditions demonstrate the involvement of both nonhydride and metal-hydride medium and can be switchable with water as an additive...
April 20, 2017: Journal of Organic Chemistry
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