- An efficient synthesis of benzothiazole using tetrabromomethane as a halogen bond donor catalyst
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An efficient and mild protocol has been developed for the synthesis of 2-substituted benzothiazole under solvent- and metal-free conditions using CBr4 as the catalyst. This process involves the activation of a thioamide through halogen bond formation between the sulphur atom of the thioamide and bromine atom of the CBr4 molecule. The presence of halogen-bonding interaction between N-methylthioamides and tetrabromomethane has been demonstrated with several control experiments, spectroscopic analysis and density functional theory (DFT). This methodology has a wide substrate scope for the synthesis of both 2-alkyl and 2-aryl substituted benzothiazoles.
- Kazi, Imran,Sekar, Govindasamy
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p. 9743 - 9756
(2019/12/02)
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- Intramolecular 1,5-H transfer reaction of aryl iodides through visible-light photoredox catalysis: A concise method for the synthesis of natural product scaffolds
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The intramolecular 1,5-H transfer reaction of the aryl radicals generated from unactivated aryl iodides by photocatalysis is described. The features of this transformation are operational simplicity, excellent yields, mild reaction conditions, and good fu
- Chen, Jian-Qiang,Wei, Yun-Long,Xu, Guo-Qiang,Liang, Yong-Min,Xu, Peng-Fei
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p. 6455 - 6458
(2016/05/24)
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- Generation of Hydrogen from Water: A Pd-Catalyzed Reduction of Water Using Diboron Reagent at Ambient Conditions
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Production of hydrogen from renewable sources, particularly from water, is an intensive area of research, which has far-reaching relevance in hydrogen economy. A homogeneous catalytic method is presented for producing clean hydrogen gas from water, in a reaction of water with a diboron compound as the reductant, under ambient reaction conditions. The Pd-catalytic system is stable in water and displays excellent recyclability. Hydroxy analogues such as alcohols are compatible with the Pd/B2Pin2 system and generate hydrogen gas efficiently. The B2Pin2-H2O system, in the presence of palladium, is an excellent catalytic system for selective hydrogenation of olefins.
- Ojha, Devi Prasan,Gadde, Karthik,Prabhu, Kandikere Ramaiah
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supporting information
p. 5062 - 5065
(2016/10/14)
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- Transition metal and base-free synthesis of 3,3-diaryl-2-oxindoles from 2,2,N-triarylacetamides
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A transition metal and base-free synthesis of 3,3-diaryl-2-oxindoles has been developed from 2,2,N-triarylacetamides in the presence of montmorillonite K-10 in 1,2-dichlorobenzene under O2 balloon atmosphere.
- Lim, Jin Woo,Kim, Ko Hoon,Moon, Hye Ran,Kim, Jae Nyoung
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supporting information
p. 784 - 787
(2016/02/03)
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- Nickel-catalyzed dehydrogenative cross-coupling: Direct transformation of aldehydes into esters and amides
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By exploring a new mode of nickel-catalyzed cross-coupling, a method to directly transform both aromatic and aliphatic aldehydes into either esters or amides has been developed. The success of this oxidative coupling depends on the appropriate choice of catalyst and organic oxidant, including the use of either α,α,α-trifluoroacetophenone or excess aldehyde. Mechanistic data that supports a catalytic cycle involving oxidative addition into the aldehyde C-H bond is also presented.
- Whittaker, Aaron M.,Dong, Vy M.
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supporting information
p. 1312 - 1315
(2015/01/30)
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- Amide bond formation through iron-catalyzed oxidative amidation of tertiary amines with anhydrides
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A general and efficient method for amide bond synthesis has been developed. The method allows for synthesis of tertiary amides from readily available tertiary amines and anhydrides in the presence of FeCl2 as catalyst and tert-butyl hydroperoxide in water (T-Hydro) as oxidant. Mechanistic studies indicated that the in situ-generated α-amino peroxide of tertiary amine and iminium ion act as key intermediates in this oxidative transformation.
- Li, Yuanming,Ma, Lina,Jia, Fan,Li, Zhiping
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p. 5638 - 5646
(2013/07/26)
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- Synthesis of indolones via radical cyclization of N-(2-halogenoalkanoyl)- substituted anilines
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The radical reactions of N-(2-halogenoalkanoyl)-substituted anilines (anilides) of type 1 have been investigated under various conditions. Treatment of compounds 1a-1o with Bu3SnH in the presence of (2,2′-azobis(isobutyronitrile) (AIBN) afforded a mixture of the indolones (oxindoles) 2a-2o and the reduction products 5a-5o (Table 1). In contrast, the N-unsubstituted anilides 1p-1s, 1u, and 1v gave the corresponding reduction products exclusively (Table 1). Similar results were obtained by treatment of 1 with Ni powder (Table 2) or wth Et3B (Table 3). Anilides with longer N-(phenylalkyl) chains such as 6 and 7 were inert towards radical cyclization, with the exception of N-benzyl-2-bromo-N,2-dimethylpropanamide (6b), which, upon treatment with Ni powder in i-PrOH, afforded the cyclized product 9b in low yield (Table 4). Upon irradiation, the extended anilides 6, 7, 10, and 11 yielded the corresponding dehydrobromination products exclusively (Table 5).
- Nishio, Takehiko,Iseki, Kyoko,Araki, Norihito,Miyazaki, Takenori
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- The extraordinary reactions of phenyldimethylsilyllithium with N,N-disubstituted amides
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The reactions of the silyllithium reagent with tertiary amides was discussed. The enediamines were easily isomerized from cis to trans, easily oxidized to dienediamines and were hydrolyzed to α-aminoketones. If the two equivalents of the silyllithium reagent were used, the product was an α-silylamine. The results show that each member of the homologous series of amides gives rise to a substantially different product.
- Buswell, Marina,Fleming, Ian,Ghosh, Usha,Mack, Stephen,Russell, Matthew,Clark, Barry P.
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p. 3006 - 3017
(2007/10/03)
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- Diethylphosphine oxide (DEPO): High-yielding and facile preparation of indolones in water
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(Matrix presented) Indolones are prepared in excellent yield at 80°C in water by radical reaction (aryl radical formation, hydrogen atom abstraction, cyclization, and rearomatization) mediated by the reagent diethylphosphine oxide (DEPO). The reaction fea
- Khan, Tanweer A.,Tripoli, Regis,Crawford, James J.,Martin, Concepcion G.,Murphy, John A.
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p. 2971 - 2974
(2007/10/03)
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- A general and practical method of synthesis of 2-disubstituted-1- chloro- and 1-bromoenamines
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Disubstituted-α-chloroenamines are useful synthetic intermediates which had earlier been prepared by the reaction of tertiary amides with phosgene. The toxicity of the latter led us to systematically investigate new synthetic routes towards α-chloro- and
- Ghosez, Leon,George-Koch, Isabelle,Patiny, Luc,Houtekie, Marc,Bovy, Philippe,Nshimyumukiza, Prosper,Phan, Thao
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p. 9207 - 9222
(2007/10/03)
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- Palladium-Catalyzed Inter- and Intramolecular α-Arylation of Amides. Application of Intramolecular Amide Arylation to the Synthesis of Oxindoles
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2A palladium-catalyzed α-arylation of amides is reported. Intermolecular arylation of N,N-dimethylamides and lactams occurs using aryl halides, silylamide base, and a palladium catalyst. Intramolecular arylation of N-(2-halophenyl)amides occurs using alkoxide base and a palladium catalyst. The palladium catalyst was formed in situ from Pd(dba)2 (dba = trans,trans-dibenzylidene acetone) and BINAP (2,2′-bis(diphenylphosphino)-1,1′-binaphthalene). Although the intermolecular arylation of amides is less general than that reported previously for ketones, unfunctionalized and electron-rich aryl halides gave α-arylamides in 48-75% yield and N-methyl-α-phenylpyrrolidinone in 49% yield. These reactions provided the highest yields yet reported for regioselective amide arylations. Intramolecular amide arylation of 2-bromoanilides gave oxindoles in 52-82% yield. Mono- and disubstituted acetanilides gave 1,3-di- and 1,3,3-trisubstituted oxindoles. The use of dioxane, rather than THF, solvent was important for some of the amide arylations.
- Shaughnessy, Kevin H.,Hamann, Blake C.,Hartwig, John F.
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p. 6546 - 6553
(2007/10/03)
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- Tandem Radical Translocation and Homolytic Aromatic Substitution: a Convenient and Efficient Route to Oxindoles
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Suitable o-bromo-N-methylanilides are efficiently converted into oxindoles by treatment with tributylstannane at 160 degC via tandem translocation of the initially formed aryl radical and intramolecular homolytic substitution.
- Beckwith, Athelstan L. J.,Storey, John M. D.
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p. 977 - 978
(2007/10/02)
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- Electrochemistry of 2-Bromo-2-methylpropanamides. Reduction Mechanism and Cyclocoupling Reaction with Amide Solvents
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The electrochemical reduction of series of secondary and tertiary α-bromoisobutyramides has been studied in dipolar aprotic solvents.A carbanion is formed at the mercury electrode as a consequence of two-electron C-Br bond cleavage.Voltammetry and macroelectrolysis point to a self-protonation mechanism, the carbanion undergoing protonation by a parent molecule to yield the isobutyramide.Concurrently, tertiary 2-bromoamides undergo 1,2-elimination to yield an αβ-unsaturated amide, while secondary 2-bromoamides are deprotonated at the nitrogen atom, affording a bromo-containing anion.The decay of the latter is strongly dependent on the solvent and the substituent at nitrogen.In acetonitrile, elimination and fragmentation products are identified in the electrolysed solution.On the other hand, in N,N-dimethylformamide or N,N-dimethylacetamide, the bromo-containing anion is eventually cyclocondensed onto the carbonyl group of the amide solvent, to yield an oxazolidin-4-one derivative.Preliminary data suggest that an analogous cyclocoupling reaction takes place when the reduction is carried out in 1-methyl-2-pyrrolidone.
- Maran, Flavio,Vianello, Elio,D'Angeli, Ferruccio,Cavicchioni, Giorgio,Vecchiati, Giorgio
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- Electrochemical Reduction of 2-Bromo-carboxamides. Self-protonation Mechanism and Reaction with Dimethylformamide
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Electrochemical reduction of 2-bromo-carboxamides involves self-protonation of the electrogenerated bases and affords, among other products, cyclo-adducts incorporating a dimethylformamide unit.
- Maran, Flavio,Vianello, Elio,Cavicchioni, Giorgio,D'Angeli, Ferruccio
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- Photochemically Induced Reactions of 3-Amino-2H-azirines
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Irradiation of 3-(N-methylanilino)-2H-azirines with a mercury low pressure lamp induces the cleavage of the C(2), C(3)-ring bond thus affording nitriliomethanide dipols, substituted by an amino group at C(1).Depending on the substitution pattern at C(3),
- Dietliker, Kurt,Heimgartner, Heinz
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p. 262 - 295
(2007/10/02)
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