- A Smart Latent Catalyst Containing o-Trifluoroacetamide Functional Benzoxazine: Precursor for Low Temperature Formation of Very High Performance Polybenzoxazole with Low Dielectric Constant and High Thermal Stability
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A novel difunctional benzoxazine with o-trifluoroacetamide functionality has been synthesized via Mannich condensation. The chemical structure of synthesized monomer has also been confirmed by 1H, 13C, and 19F nuclear magn
- Zhang, Kan,Han, Lu,Froimowicz, Pablo,Ishida, Hatsuo
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- Direct C-N bond cleavage of N-vinyl or N-allyl arylamines: A metal-free strategy for N-devinylation and N-deallylation
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A simple and convenient N-devinylation and N-deallylation strategy for N-vinyl and N-allyl arylamines in the presence of TFA/oxone is presented with the formation of selective ortho-hydroxylated and N-trifluoroacylated arylamine product in good yields. Th
- Balgotra, Shilpi,Venkateswarlu, Vunnam,Vishwakarma, Ram A.,Sawant, Sanghapal D.
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supporting information
p. 4289 - 4292
(2015/06/22)
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- Metal-free chemoselective ortho -C(sp2)-F bond hydroxylation and N-trifluoroacylation of fluoroarylamines for domino synthesis of 2-(N-trifluoroacyl)aminophenols
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Abstract A novel chemoselective reaction for the formation of C-O bonds by C(sp2)-F bond cleavage and concomitant N-trifluoroacylation of fluoroanilines using trifluoroacetic acid and Oxone is presented. This domino reaction gives o-hydroxy-N-trifluoroacetanilides in good yields under metal-free conditions in a single step. Selective ortho-directed monohydroxylation and N-trifluoroacylation of 2- and 6-fluoro- or 2,6-difluoro-substituted anilines takes place in this transformation.
- Venkateswarlu, Vunnam,Balgotra, Shilpi,Aravinda Kumar,Vishwakarma, Ram A.,Sawant, Sanghapal D.
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supporting information
p. 1258 - 1262
(2015/06/02)
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- C-H oxygenation and N-trifluoroacylation of arylamines under metal-free conditions: A convenient approach to 2-aminophenols and N-trifluoroacyl-ortho- aminophenols
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Direct ortho-hydroxylation through C-H oxygenation and N-trifluoroacylation of anilines was achieved in a single step under metal-free conditions by using a combination of TFA and oxone. The method allowed the formation of functionalised amino phenolic compounds such as ortho-hydroxy-N- trifluoroacetanilides in good yields with broad substrate scope.
- Venkateswarlu, Vunnam,Kumar, K. A. Aravinda,Balgotra, Shilpi,Reddy, G. Lakshma,Srinivas,Vishwakarma, Ram A.,Sawant, Sanghapal D.
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supporting information
p. 6641 - 6645
(2014/06/09)
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- Pd-catalyzed sp2 C-H hydroxylation with TFA/TFAA via weak coordinations
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An efficient sp2 C-H hydroxylation has been developed for the synthesis of a wide range of functionalized phenols with aryl ketones, benzoates, benzamides, acetanilides and sulfonamides through palladium(II) catalysis. A trifluoroacetic acid (TFA)/trifluoroacetic anhydride (TFAA) co-solvent system serves as the oxygen source and is the critical factor for weak coordination promoted C-H activation. Georg Thieme Verlag Stuttgart New York.
- Rao, Yu
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p. 2472 - 2476
(2013/12/04)
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- Pd-catalyzed C-H oxygenation with TFA/TFAA: Expedient access to oxygen-containing heterocycles and late-stage drug modification
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Functionalized phenols are valuable industrial chemicals related to pharmaceuticals, agrochemicals, and polymers. Therefore, the direct catalytic hydroxylation of arenes to produce phenols has attracted much attention. Although tremendous progress has been made in this field, there are still difficult substrates which remain unmet challenges for direct hydroxylation in terms of regio- and chemoselectivity, as well as the practicality of current methods (Scheme 1). For example, 2-hydroxy aromatic ketones are useful synthetic intermediates for the preparation of various oxygen-containing heterocycles such as benzofuranone, chromanone, benzoxazole, and dibenzooxazepine; they also serve as key building blocks for drugs such as celiprolol, acebutolol, and propafenone. Traditional strategies for accessing 2-hydroxy aromatic ketones have mainly involved the oxidation of benzylic alcohols, the hydrolysis of aromatic halides, Fries rearrangement of esters or the demethylation of methyl phenyl ether. These methods generally suffer from one limitation or another, such as tedious reaction procedures, harsh reaction conditions, low yields, or the formation of side products. Hence, direct transformation of readily available aromatic ketones into valuable 2-hydroxylated products by transition metal-catalyzed C-H functionalization is arguably a highly efficient and atom-economic method to access these compounds. Moreover, developing a more general strategy for the regio- and chemoselective C-H oxygenation of a variety of challenging arenes would be especially desirable for phenol synthesis (Scheme 1).
- Shan, Gang,Yang, Xinglin,Ma, Linlin,Rao, Yu
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supporting information
p. 13070 - 13074
(2013/02/26)
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- Reactions of epoxides derived from internal perfluoroolefins with o-phenylenediamine and 2-aminophenol
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The reactions of epoxy derivatives of internal perfluoroolefins with o-phenylenediamine and 2-aminophenol in dioxane gave 23-67% of the corresponding 2,3-bis(perfluoroalkyl)quinoxalines and 2,3-bis-(perfluoroalkyl)-2H-1,4- benzoxazin-2-ols, respectively. When N,N-dimethylacetamide was used as a solvent, the main reaction pathway was anionic isomerization of epoxides into ketones which were then converted into 2-perfluoroalkylbenzimidazoles (in the reactions with o-phenylenediamine) or 2-hydroxy-N-perfluoroalkanoylanilines (in the reactions with 2-aminophenol). The reaction of 3,4-epoxydodecafluorohexane with 2-aminophenol in N,N-dimethylacetamide was accompanied by unusual cyclization to afford 2-pentafluoropropanoyl-2-pentafluoroethyl-1,3- benzoxazolidine. Pleiades Publishing, Inc., 2006.
- Saloutina,Zapevalov,Saloutin,Kodess,Kirichenko,Pervova,Chupakhin
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p. 558 - 566
(2007/10/03)
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- Synthesis of 2,3-bis(perfluoroalkyl)quinoxalines and 2,3- bis(perfluoroalkyl)-1,4-benzoxazines from oxides of internal perfluoroolefins
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The reactions of oxides of internal trans-, cis-perfluoroolefins with o-phenylenediamine and 2-aminophenol in dioxane gave 2,3-bis(perfluoroalkyl) quinoxalines and 2,3-bis(perfluoroalkyl)-2H-1,4-benzoxazin-2-ols respectively in yields of 23-67%. When N,N-dimethylacetamide was used as a solvent an anionic isomerization of the oxides into ketones, which further yielded 2-(perfluoroalkyl)benzimidazoles in the case of o-phenylenediamine and 2-hydroxy-N-perfluoroalkanoylanilines in the case of 2-aminophenol, became the main path of these reactions. Unusual cyclization resulting in 2-pentafluoroethyl-2-pentafluoropropanoylbenzoxazolidine occurs on interaction between dodecafluoro-3,4-epoxyhexane and 2-aminophenol in N,N-dimethylacetamide.
- Saloutina, Lyudmila V.,Zapevalov, Aleksandr Ya.,Saloutin, Victor I.,Kodess, Mikhail I.,Kirichenko, Valentina E.,Pervova, Marina G.,Chupakhin, Oleg N.
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p. 976 - 983
(2007/10/03)
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- An approach to metal-assisted DNA base pairing: Novel β-C-nucleosides with a 2-aminophenol or a catechol as the nucleobase
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The metal-chelating β-C-nucleoside having a phenylenediamine moiety as the nucleobase was previously found to form a stable 2:1 complex with a Pd2+ ion in aqueous media, where hydrogen bonding is replaced by metal coordination in the base pairing, thereby creating a novel hybridization motif in duplex DNA. In this regard, we have further designed two types of artificial β-C-nucleosides possessing a metal-chelating site (a 2-aminophenol or a catechol) as the nucleobase moiety. These artificial nucleosides are directed toward controlling the net charges of the metal-assisted base pairs. This paper describes convenient syntheses of the artificial nucleosides bearing a 2-aminophenol or a catechol moiety. Each nucleoside was directly synthesized through 2′-deoxy derivative via a Friedel-Crafts coupling reaction as the key step between the aromatic ring and ribose moiety, whereas the nucleoside having a phenylenediamine moiety was prepared in rather longer steps through an RNA type intermediate followed by the removal of 2′-hydroxyl group. Copyright
- Tanaka,Tasaka,Cao,Shionoya
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- 3-(2-aminomethyl)-4-[3-trifluoromethyl)benzoyl]-3-4 dihydro-2h-1,4-benzoxazine derivatives and their therapeutic application
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Compounds of the general formula (I) STR1 wherein R1 represents a hydrogen, fluorine or chlorine atom or a methyl, C1 -C3 alkoxy or nitro group; R3 represents a hydrogen atom or a C1 -C3 alkyl group; R4 represents a 2,3-dihydro-1H-inden-2-yl, 2,3-dihydro-1H-inden-1-yl or 1,2,3,4-tetrahydronaphthalen-1-yl group; or alternatively R3 and R4 complete, with the nitrogen atom to which they are attached, a 1,2,3,4-tetrahydro-9H-pyrido[3,4-b]indol-2-yl, 1,2,3,4-tetrahydro-9H-pyrido[4,3-b]indol-3-yl, 4,5,6,7-tetrahydrothieno[2,3-c]pyrid-6-yl, 4,5,6,7-tetrahydrothieno[3,2-c]pyrid-6-yl or 2,3-dihydro-1H-isoindol-2-yl group; are useful for the treatment and prevention of cerebral disorders.
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- Acid-catalyzed amino-migration of O-phenylhydroxylamines
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The mechanism of amino-migration of O-phenylhydroxylamine (1a) was studied. It was found that 1 rearranges to give 2-aminophenol (50%) and 4-aminophenol (7%) in trifluoroacetic acid (TFA). The predominance of the ortho rearrangement of 1 clearly distinguishes this process from the Bamberger rearrangement. From cross-coupling experiments employing stable isotopes, it was clarified that the ortho rearrangement proceeds intramolecularly and the para rearrangement involves both intra- and intermolecular processes. Good first-order kinetics were obtained for the rearrangement. The Hammett plot (σ+) with a large negative slope (ρ = -7.8) indicates that initial heterolytic N-O bond cleavage of 1 occurs and generates a positive charge on the oxygen atom with considerable delocalization into the aromatic ring. An ion-molecule pair involving a phenoxenium ion and an ammonia molecule as an intermediate rationalizes all of the results. In this pair, intramolecular combination to the ortho position proceeds preferentially over that to the para position. Formation of catechol and hydroquinone can be explained in terms of nucleophilic attack of TFA on the phenoxenium ion in a solvent-separated pair.
- Haga, Naoki,Endo, Yasuyuki,Kataoka, Ken-Ichiro,Yamaguchi, Kentaro,Shudo, Koichi
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p. 9795 - 9806
(2007/10/02)
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- 2-(Trifluoroacetyloxy)pyridine as a Mild Trifluoroacetylating Reagent of Amines and Alcohols
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A new trifluoroacetylating reagent, 2-(trifluoroacetyloxy)pyridine (TFAP), was prepared by the reaction of 2-pyridinol and trifluoroacetic anhydride.TFAP has been found to be effective in the trifluoroacetylation of aliphatic and aromatic amines and alcohols including phenol under mild conditions.The reaction of p-nitrophenol with TFAP in ether gave the hydrogen-bonded complex between the phenol and 2-pyridone.This reagent has also been shown to be useful for the intramolecular dehydration of aldehyde oximes and amides to give nitriles in high yields.
- Keumi, Takashi,Shimada, Masakazu,Morita, Toshio,Kitajima, Hidehiko
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p. 2252 - 2256
(2007/10/02)
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