- Mechanistic investigations on C-H activated dealkylating cyclo-amination reactions of substituted triazenes, formamidines and amidines
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Catalytic dealkylating cycloamination reactions of N 1-methylated-N 1,N 3-diarylated triazenes proceed via two subsequent oxidative addition reactions, regioselectivity producing benzotriazoles by C-H and C-Br activation steps. Whereas palladium-based catalysis in the presence of dealkylating reagents and directing phosphane ligands leads to high yields, the homologous metals nickel and platinum as well as other 3d transition metals show only poor catalytic activity in similar procedures. Starting compounds have been widely varied to introduce potentially competing reaction sites and to investigate the reaction mechanism of the catalytic cyclization reactions. Yields of the benzotriazole synthesis strongly depend on the electronic and steric properties of the directing phosphane ligands, the nature of the dealkylating bases and the substitution pattern in 2- A nd 4-position of the aryl groups of the starting triazenes. In order to clarify the role of the catalyst, palladium-based intermediates were identified. Finally, formamidines and bulky amidines were tested in related C-H activated dealkylating cycloamination reactions.
- Preusser, Silvio,Kalden, Diana,Wendler, Felix,Sch?nherr, Paul R. W.,G?rls, Helmar,Westerhausen, Matthias,Imhof, Wolfgang
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p. 651 - 664
(2020/07/27)
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- The Disappearing Director: The Case of Directed N-Arylation via a Removable Hydroxyl Group
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A facile and broadly applicable method for the regiospecific N-arylation of benzotriazoles is reported. Copper-mediated reactions of diverse 1-hydroxy-1H-benzotriazoles with aryl boronic acids lead to 1-aryl-1H-benzotriazole 3-oxides. A N1-OH→N3 prototropy in the 1-hydroxy-1H-benzotriazoles is plausibly the underlying basis, where the tautomer is captured by the boronic acid, leading to C?N (not C?O) bond formation. Because the N?O bond in amine N-oxides and 1-hydroxy-1H-benzotriazoles can be easily reduced by diboron reagents such as (pinB)2 and B2(OH)4, exposure of the 1-aryl-1H-benzotriazole 3-oxides to B2(OH)4 then leads to facile reduction of the N?O bond resulting in diverse, regiospecifically-arylated benzotriazoles. Thus, the N-hydroxyl group in 1-hydroxy-1H-benzotriazoles acts as a disposable arylation director. (Figure presented.).
- Andrzejewska, Magdalena R.,Vuram, Prasanna K.,Pottabathini, Narender,Gurram, Venkateshwarlu,Relangi, Siva Subrahmanyam,Korvinson, Kirill A.,Doddipalla, Raju,Stahl, Lothar,Neary, Michelle C.,Pradhan, Padmanava,Sharma, Somesh,Lakshman, Mahesh K.
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supporting information
p. 2503 - 2510
(2018/05/08)
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- Photochemical C–H Activation: Generation of Indole and Carbazole Libraries, and First Total Synthesis of Clausenawalline D
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The photolysis of N-aryltriazoles and N-arylbenzotriazoles leads to indoles and carbazoles, respectively. Because libraries of triazoles can be accessed rapidly, for example by the copper-catalyzed [3+2] cycloaddition reaction between alkynes and azides, this reaction allows the preparation of indoles in a single operation, by the simultaneous photolysis of the precursor library. As an example of such a synthesis of carbazoles, we prepared for the first time clausenawalline D, an antimalarial alkaloid that was recently isolated.
- Alimi, Isak,Remy, Richard,Bochet, Christian G.
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p. 3197 - 3210
(2017/06/21)
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- Base-mediated N- And O-arylations of NH-containing heterocycles, heterocyclic amines and phenols
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Nucleophilic substitution reactions of N-heterocycles such as imidazole, benzimidazole, indole and pyrazole as well as NH2 or OH containing heterocycles, with electron-deficient aryl halides in the presence of t-BuOK or K2CO3as base and DMSO as solvent are reported. A series of N-aryl azoles, unsymmetric diaryl ethers and diaryl amines were obtained in good yields.
- Ghasemi, Zarrin,Shahrak, Nasim Shahi,Roomi, Behzad Jalali,Zakeri, Ziba
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- A one-step method for preparation of Cu@Cu2O nanoparticles on reduced graphene oxide and their catalytic activities in N-arylation of N-heterocycles
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Core-shell Cu@Cu2O nanoparticles on reduced graphene oxide (Cu@Cu2O NPs-RGO) nanocomposite were prepared at room temperature by in situ reduction of graphene oxide (GO) and copper sulfate using l-ascorbic acid as reducing agent and t
- Movahed, Siyavash Kazemi,Dabiri, Minoo,Bazgir, Ayoob
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- A photoinduced, benzyne click reaction
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The [3 + 2] cycloaddition of azides and alkynes has proven invaluable across numerous scientific disciplines for imaging, cross-linking, and site-specific labeling among many other applications. We have developed a photoinitiated, benzyne-based [3 + 2] cycloaddition that is tolerant of a variety of functional groups as well as polar, protic solvents. The reaction is complete on the minute time scale using a single equivalent of partner azide, and the benzyne photoprecursor is stable for months under ambient light at room tempurature. Herein we report the optimization and scope of the photoinitiated reaction as well as characterization of the cycloaddition products.
- Gann, Adam W.,Amoroso, Jon W.,Einck, Vincent J.,Rice, Walter P.,Chambers, James J.,Schnarr, Nathan A.
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p. 2003 - 2005
(2014/05/06)
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- Organocatalytic triazole formation, followed by oxidative aromatization: Regioselective metal-free synthesis of benzotriazoles
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Herein we report on our studies on the sequential one-pot combinations of amine-catalyzed multicomponent reactions (MCRs). We have developed the copper-free synthesis of functionalized bicyclic N-aryl-1,2,3-triazole and N-arylbenzotriazole products 4 and 5 from the simple unmodified starting materials through [3+2]-cycloaddition ([3+2]-CA) and oxidative aromatization reactions in one pot under amine catalysis. The sequential one-pot reaction proceeds in good yields with high selectivity by using pyrrolidine as the catalyst from the simple unmodified substrates of enones, aryl azides, and 2,3-dichloro-5,6-dicyano-1,4-benzoquinone (DDQ). Furthermore, we have demonstrated the medicinal applications of products 4 and 5 through simple organic reactions. Organo-click approach to benzotriazoles: A practical synthesis of N-arylbenzotriazoles was achieved through the sequential one-pot combination of [3+2]-cycloaddition followed by 2,3-dichloro-5,6-dicyano-1,4- benzoquinone (DDQ)-mediated oxidative aromatization of unmodified cyclic enones with aryl azides. For the first time, the synthesis of privileged CF3 containing N-arylbenzotriazoles through metal-free catalysis has been discovered (see scheme). Copyright
- Ramachary, Dhevalapally B.,Shashank, Adluri B.
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supporting information
p. 13175 - 13181
(2013/10/01)
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- TBAF-assisted copper-catalyzed N-arylation and benzylation of benzazoles with aryl and benzyl halides under the ligand/base/ solvent-free conditions
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(Equation Presented) TBAF-assisted N-arylation and benzylation of benzazoles such as 1H-benzimidazole, 1H-indole, and 1H-benzotriazole with aryl and benzyl halides have been demonstrated under the ligand/base/solvent-free conditions. In the presence of CuBr2 and TBAF (n-Bu4NF), the azoles underwent N-arylation and benzylation with aryl and benzyl halides smoothly in moderate to good yields. It is noteworthy that the reaction is conducted under the ligand/base/solvent-free conditions.
- Lee, Hyung-Geun,Won, Ju-Eun,Kim, Min-Jung,Park, Song-Eun,Jung, Kwang-Ju,Bo, Ram Kim,Lee, Sang-Gyeong,Yoon, Yong-Jin
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supporting information; experimental part
p. 5675 - 5678
(2009/12/06)
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- Benzyne click chemistry with in situ generated aromatic azides
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An efficient synthesis of substituted benzotriazoles using an azide-alkyne 1,3-dipolar cycloaddition "click reaction" is described. Key to the procedure is the in situ generation of the reactive aromatic azide and benzyne reaction partners.
- Zhang, Fengzhi,Moses, John E.
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supporting information; experimental part
p. 1587 - 1590
(2009/08/07)
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- N,N′-(Phenylmethylene)diacetamide analogues as economical and efficient ligands in copper-catalyzed arylation of aromatic nitrogen-containing heterocycles
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N,N′-(Phenylmethylene)diacetamide analogues which were simply prepared from the condensation reaction of an aldehyde with an amide or urea were found to be efficient ligands in copper-catalyzed coupling reaction of aryl halides with various azole nucleophiles. The newly developed ligand showed broad application scope in this conversion. Compounds including imidazoles, benzoimidazoles, pyrrole, indole, and benzotriazole were successfully arylated with diversified aromatic halides to give corresponding products in moderate to excellent yields. Georg Thieme Verlag Stuttgart.
- Wan, Jie-Ping,Chai, Yun-Feng,Wu, Jian-Mei,Pan, Yuan-Jiang
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experimental part
p. 3068 - 3072
(2009/06/28)
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- Selective N(1)-arylation of benzotriazole with activated aryl halides under conditions of phase transfer catalysis
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Arylation of 1H-1,2,3-benzotriazole with activated aryl halides in a medium of aromatic hydrocarbons under conditions of phase transfer catalysis with the use of inorganic bases and cetyltrimethylammonium bromide as a phase-transfer catalyst was studied.
- Beletskaya,Davydov,Gorovoi,Kardashov
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p. 1533 - 1536
(2007/10/03)
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- Synthesis of p-nitrophenylazoles by phase transfer catalysis without solvent
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Several N-p-nitrophenylazoles have been synthesized by direct arylation of the corresponding azole with p-fluoronitrobenzene (FNB) using phase-transfer catalysis (PTC) without solvent.
- Cerrada,Elguero,De La Fuente,Pardo,Ramos
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p. 1947 - 1952
(2007/10/02)
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- SYNTHESES AND PROPERTIES OF SOME DERIVATIVES OF N--NAPHTHALIMIDE
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Syntheses of N--naphthalimide and N--naphthalimide derivatives, unreported so far in the literature have been worked out, and the products are characterized.The usefulness of some of them as optical brightening agents has been established from their fluorescence spectra.The phenomenon of an intramolecular energy transfer from the benzotriazole to naphthalimide ring systems has been observed for the derivatives of N--naphthalimide.
- Jankowski, Zdzislaw,Stolarski, Roland
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p. 555 - 564
(2007/10/02)
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