- Novel functionalized indigo derivatives for organic electronics
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A series of nine novel indigo derivatives, including diiodoindigo, octahalogenated indigoids and compounds with extended π-conjugated system, were synthesized, characterized and investigated as semiconductor materials in organic field-effect transistors (OFETs). Among them, 6,6′-diiodoindigo demonstrated the ambipolar behavior with balanced p-type and n-type mobilities. The complete substitution of hydrogens at the indigo core with halogen atoms led to low electron mobilities in OFETs. An extension of the conjugated system through the introduction of small aromatic substituents (thiophene and phenyl) resulted in predominant p-type behavior. Fusion of aromatic rings resulted in z-shaped dibenzoindigo, which showed poor charge transport properties due to the non-optimal arrangement of molecules along each other in the crystal lattice. The acquired data fulfilled the previously reported model based on the relationship between the chemical nature of substituents and their positions at the indigo core, optoelectronic properties of materials and their performance in OFETs. The results of this study will be useful for rational design of a new generation of the indigo-based semiconductors for biocompatible organic electronics.
- Klimovich, Irina V.,Zhilenkov, Alexander V.,Кuznetsova, Lidiya I.,Frolova, Lubov A.,Yamilova, Olga R.,Troyanov, Sergey I.,Lyssenko, Konstantin A.,Troshin, Pavel A.
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- Corey-Chaykovsky Cyclopropanation of Nitronaphthalenes: Access to Benzonorcaradienes and Related Systems
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Nitronaphthalene derivatives react as Michael acceptors in the Corey-Chaykovsky reaction with alkyl phenyl selenones and alkyl diphenyl sulfonium salts. Mechanistic studies reveal that sterically demanding substituents at the carbanionic center favor formation of cyclopropanes and suppress competitive β-elimination to the alkylated products. The transformation, demonstrated also on heterocyclic nitroquinoline and nitroindazolines, is an example of transition metal-free dearomatization method.
- Antoniak, Damian,Barbasiewicz, Micha?
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supporting information
p. 9320 - 9325
(2019/11/19)
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- Ceric ammonium nitrate (CAN) as oxidizing or nitrating reagent for organic reactions in ionic liquids
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The reaction of ceric ammonium nitrate, (NH4)2[Ce(NO3)6] or CAN, with naphthalene and 2-methylnaphthalene in the ionic liquid 1-ethyl-3-methylimidazolium triflate showed that the reaction products are strongly d
- Deleersnyder, Karen,Schaltin, Stijn,Fransaer, Jan,Binnemans, Koen,Parac-Vogt, Tatjana N.
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scheme or table
p. 4582 - 4586
(2009/10/11)
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- A facile synthesis of 2-methylquinolines via Pd-catalyzed aza-Wacker oxidative cyclization
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(Chemical Equation Presented) A novel Pd-catalyzed Wacker-type oxidative cyclization under air is described. By using this cyclization, a series of 2-methylquinolines are readily prepared with good yields under mild conditions.
- Zhang, Zuhui,Tan, Jiajing,Wang, Zhiyong
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p. 173 - 175
(2008/09/18)
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- Selective ortho methylation of nitroheteroaryls by vicarious nucleophilic substitution
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(Chemical Equation Presented) An efficient and scalable three-step one-pot approach to 6-methyl-5-nitroisoquinoline (1) from inexpensive 5-nitroisoquinoline, utilizing the vicarious nucleophilic substitution (VNS) as a key step, is described. The optimized reaction conditions can be applied to a limited number of other aromatic and heteroaromatic nitro compounds. Attempts to understand the observed selectivity in the VNS step led to the discovery of two new reaction pathways under VNS conditions, one leading to an isoxazole and the other resulting in the formal cyclopropanation of an aromatic nitro compound.
- Achmatowicz, Michal,Thiel, Oliver R.,Gorins, Gilles,Goldstein, Corinne,Affouard, Caroline,Jensen, Randy,Larsen, Robert D.
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p. 6793 - 6799
(2008/12/22)
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- Indium triflate as a recyclable catalyst for the nitration of aromatic compounds without a halogenated solvent
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Indium triflate [In(OTf)3] was found to be excellent catalyst (0.5 or 2.0 mol%) for the mononitration of aromatic compounds using a single equivalent of nitric acid (60 or 90%, 1.0 equiv.) without using a halogenated solvent. The side product is water and the indium triflate catalyst can be readily recovered from the aqueous phase and reused.
- Yin, Wan-Po,Shi, Min
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p. 549 - 551
(2007/10/03)
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- New Types of Very Efficient Photolabile Protecting Groups Based upon the [2-(2-Nitrophenyl)propoxy]carbonyl (NPPOC) Moiety
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Based upon the photolabile [2-(2-nitrophenyl)propoxy]carbonyl group (NPPOC), a large number of modified 2-(2-nitrophenyl)propanol derivatives substituted at the phenyl ring (see 23-34 and 57-76) as well as at the side-chain (see 85-92 and 95-98) were synthesized to improve the photoreactivity of this new type of photolabile entity. The phenyl moiety was also exchanged by the naphthalenyl group (see 102, 103, 105, 108, 110, 113, and 114), the thienyl substituent (see 115, 117, 118, and 120), and the benzothienyl substituent (see 121). The 2-(2-nitroaryl- and heteroaryl) propanols were converted with diphosgene into the corresponding carbonochloridates, which reacted subsequently with thymidine to the thymidine 5′-(protected carbonates) 123-178 as the main reaction products. In several cases, the corresponding 3′-carbonates and 3′,5′ -dicarbonates 179-212 were also isolated and characterized. Photolysis studies under standardized conditions (see Table) indicated that the rate of photocleavage varies in a broad range depending on the substituents. So far, the thymidine 5′-[2-(5-halo-2-nitrophenyl)propyl carbonates] 127-129, 5′-[2-(nitro[1,1′-biphenyl]3-yl)propyl carbonates] 136-139, 5′-{2-[2-nitro-5-(thianthren-1-yl)phenyl]propyl carbonate} (140), 5′-[2-(5-naphthalenyl-2-nitrophenyl)propyl carbonates] 141 and 142, and 5′-[2-(2-nitro-5-thienylphenyl)propyl carbonates] 143 and 144 showed the best properties regarding fast and uniform deprotection. Since the nucleobases of 213-215 do not influence the photocleavage features, in general, the new type of photolabile building blocks allows in form of their 3′ -phosphoramidites the photolithographic formation of high-quality biochips.
- Buehler, Sigrid,Lagoja, Irene,Giegrich, Heiner,Stengele, Klaus-Peter,Pfleiderer, Wolfgang
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p. 620 - 659
(2007/10/03)
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- Selective nitration of aromatic compounds with bismuth subnitrate and thionyl chloride
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Bismuth subnitrate/thionyl chloride have been found to be an efficient combination of reagents for nitration of a wide range of aromatic compounds in dichloromethane. Phenols, in particular, were easily mononitrated and dinitrated with the reagents by controlling the stoichiometry.
- Muathen, Hussni A.
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p. 593 - 598
(2007/10/03)
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- First use of axially chiral thioamides for the stereocontrol of C-C bond formation
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Several N-aryl-substituted thioamides with an axis of chirality along the N-C(aryl) bond were prepared in good to excellent yields. NMR spectra revealed preferences for the E rotamer (along the N-C(=S) bond). X-ray crystallographic analysis showed that the planes of the aryl and thioamide groups were almost perpendicular (79°). For the first time, these atropisomeric thioamides were used for an asymmetric Claisen rearrangement. LDA deprotonation led selectively to the enethiolates of Z stereochemistry, and subsequent reaction with a variety of allyl halides furnished S-allyl keteneaminothioacetals. These intermediates were not detected as they rearranged readily to γ-unsaturated thioamides in good to high yields and diastereoselectivities up to 88:12. Chemical correlation allowed the assignment of the (aR*,2R*) configuration to the major diastereoisomer. A model was proposed to explain the stereochemical course of the thio-Claisen rearrangement.
- Dantale, Shubhada,Reboul, Vincent,Metzner, Patrick,Philouze, Christian
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p. 632 - 640
(2007/10/03)
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- Synthesis of 2,1-benzisoxazole derivatives from nitroarenes and CH acids in aprotic media
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DBU/MgCl2 mediated reaction between nitroarenes and some CH acids bearing leaving group lead to 2,1-benzisoxazole derivatives under aprotic conditions. Ortho-directing effect was observed.
- Wrobel
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p. 2384 - 2388
(2007/10/03)
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- Introduction of benzo[h]quinoline and 1,10-phenanthroline subunits by friedl?nder methodology
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An improved preparation of 8-amino-7-quinolinecarbaldehyde has been developed. The methyl group of 7-methyl-8-nitroquinoline may be oxidized to an aldehyde by treatment first with dimethylformamide dimethyl acetal followed by sodium periodate. Reduction with iron provides the amino aldehyde. An analogous sequence affords 1-amino-2-naphthalenecarbaldehyde. Friedl?nder condensation of the quinoline derivative with a series of acetylaromatics provides the corresponding 2-aryl-1,10-phenanthrolines. Condensation of either amino aldehyde with 1,3-diacetylbenzene or 2,6-diacetylpyridine provides the expected Friedl?nder product. Similar chemistry is described for reactions of the amino aldehydes with 1,4-diacetylbenzene, 4,4′-diacetylbiphenyl, 1,5-diacetylanthracene, 1,2,3,4,5,6,7,8-octahydroacridine-1,8-dione, and tetracyclo-[6.3.0.0.4,1105,9]undecane-2,7-dione (TCU-2,7-dione).
- Riesgo, Elvira C.,Jin, Xiaoqing,Thummel, Randolph P.
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p. 3017 - 3022
(2007/10/03)
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- Iron(III)-catalysed nitration of non-activated and moderately activated arenes with nitrogen dioxide-molecular oxygen under neutral conditions
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In the presence of molecular oxygen and a catalytic amount of tris(pentane-2,4-dionato)iron(III), non-activated and moderately activated arenes, which include alkylbenzenes, halogenobenzenes, phenolic ethers, naphthalene and derivatives, can be nitrated with nitrogen dioxide at ice-bath temperature or below to give the corresponding nitro derivatives in fair to good yields. An electron-transfer mechanism has been proposed, where an activated NO2-FeIII complex plays a key role in the cyclic process for converting arenes into nitroarenes.
- Suzuki, Hitomi,Yonezawa, Shuji,Nonoyama, Nobuaki,Mori, Tadashi
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p. 2385 - 2389
(2007/10/03)
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- Iodosonaphthoate catalysts for the cleavage of a reactive phosphate
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Iodosonaphthoates 3-5 are potent catalysts for the hydrolysis of P-nitro-phenyldiphenyl phosphate.
- Moss, Robert A.,Zhang, Hongmei,Chatterjee, Swati,Krogh-Jespersen, Karsten
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p. 1729 - 1732
(2007/10/02)
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- Charge-transfer Nitration of Naphthalene and the Methylnaphthalenes. Part 1. Direct Comparison with Electrophilic Aromatic Nitrations
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The various nitronaphthalenes formed in high yields from the selective photoexcitation of the EDA complexes of the naphthalene and methylnaphthalene donors (ArH) with the N-nitropyridinium and tetranitromethane acceptors are ascribed to charge-transfer nitration, arising as they do from the cation-radical pairs .+, NO2>.The nitration products from such an electron-transfer pathway are quantitatively compared with those from the electrophilic nitration (thermal), under otherwise the same conditions.The mechanistic implications to electrophilic aromatic substitution are discussed.
- Sankararaman, S.,Kochi, J. K.
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- Conformational Studies by Dynamic NMR. 40. Conformational Atropoisomerism in Highly Hindered Naphthylamines
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N,N-Dialkyl-1-naphthylamines substituted by alkyl groups R (R=Me, Et, i-Pr, t-Bu) in position 2 display anisochronous NMR signals owing to their twisted conformational arrangement.These conformers are enantiomerically related (conformational atropoisomers), and variable temperature NMR measurements allowed the enantiomerization barriers to be determined.The barriers increase with the increasing dimension of the substituents (covering the range 15.7-23.0 kcal mol-1), and the observed trend was reproduced by Molecular Mechanics calculations.The calculations also gaveindications upon the structure of the conformers that correspond to energy minima.The final choice among the possible conformations could be achieved by comparing the computed interprotonic distances with the results of NOE experiments.
- Davalli, S.,Lunazzi, L.,Macciantelli, D.
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p. 1739 - 1747
(2007/10/02)
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- Conformational Studies by Dynamic NMR. 37. Monitoring the Stereomutations of Symmetric Amines by Means of a Chiral Auxiliary Agent
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The chiral auxiliary agent (R)-l-2,2,2-trifluoro-1-(9-anthryl)ethanol was used to monitor the exchange between the enantiotopomers of symmetric amines lacking diastereotopic probes.The free energies of activation for stereomutations involving both C-N rotation and N-inversion processes were measured by line-shape simulation of the low-temperature NMR spectra.The effect of the chiral alcohol upon the barriers has also been evaluated, thus allowing one to compare these data with those of other amines where the stereomutations had been detected in achiral environment.The existence of steric deceleration for the exchange between enantiotopomers related by torsion and of steric acceleration for enantiotopomers related by N-inversion has been also verified.The highest N-inversion barrier observed in a simple noncyclic trialkyl amine (8.6 kcal mol-1 for Me2NEt) could thus be measured.
- Casarini, D.,Davalli, S.,Lunazzi, L.,Macciantelli, D.
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p. 4616 - 4619
(2007/10/02)
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- Nitration of Reactive Aromatics via Elelctron Transfer. V. On the Reaction between Nitrogen Dioxide and the Radical Cation Hexafluorophosphates of Some Methyl-substituted Naphthalenes
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The coupling reactions of series of methylnaphthalene radical cation hexafluorophosphates with nitrogen dioxide were studied in dichloromethane at low temperatures.Yields of nitro derivatives were generally higher with the β-methyl than with the α-methyl-substituted naphthalenes and the isomer distributions were different from those obtained in electrophilic aromatic nitration and nitrous acid catalyzed nitration.This confirm an earlier suggestion that the coupling reaction is not an elementary step of either nitration process.The high regioselectivity of the coupling reation can only partly be correlated with UHF spin densities.Pyrene+. hexafluorophosphate does not yield nitropyrenes upon treatment with nitrogen dioxide.This confirm earlier suggestions that only radical cations of aromatics with Eo values >= 1.7 V will take part in a successful (exergonic) coupling reaction with nitrogen dioxide.
- Eberson, Lennart,Radner, Finn
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- Mechanism of Reaction between Grignard Reagents and Nitroarenes. Product Distribution and Relative Reactivities of Grignard Reagents with Nitronaphthalene System
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The reaction of 2-methoxy-1-nitronaphthalene with various Grignard reagents has been examined.Alkylmagnesium halides such as CH3MgBr, PhCH2MgBr, PhCH2CH2MgBr, C2H5MgBr, and i-C3H7MgBr give 1,6-addition products almost exclusively, while PhMgBr gives instead comparable amounts of 1,4-addition and reductive 1,2-addition products.Hex-5-enylmagnesium bromide reacts giving two 1,6-addition products, one containing a straight chain and the other one a cyclized alkyl fragment, where the ratio of the two decreases with decreasing temperature.The reactivity order (i-C3H7 > PhCH2 ca.C2H5 > PhCH2CH2 > CH3) established by competitive reactions along with the reactivity pattern shown by hex-5-enylmagnesium bromide was taken as clear evidence for a single-electron transfer (s.e.t.) process.A mechanism involving s.e.t. from Grignard reagent to nitroarene followed by collapse within the solvent cage of the two radicals thus formed (geminate combination) or, to a lesser extent, out of the cage (non-geminate combination), is suggested.The reaction of 1-nitronaphthalene with methyl-, isopropyl- and hex-5-enyl-magnesium bromides indicates that the distribution of isomeric 2- and 4-alkylated products is determined by the reactivity of the ring positions for both geminate and non-geminate combination.No firm mechanistic conclusions were reached regarding the reaction of PhMgBr.
- Bartoli, Giuseppe,Bosco, Marcella,Cantagalli, Gabriele,Dalpozzo, Renato,Ciminale, Francesco
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p. 773 - 780
(2007/10/02)
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