- Alkylative Dearomatization by Using an Unactivated Aryl Nitro Group as a Leaving Group: Access to Diversified Alkylated Spiro[5.5]trienones
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The cleavage of an unactivated aryl nitro group triggered by alkyl radicals enables a dearomative cyclization, affording diversified alkylated spiro[5.5]trienones in good yields. Using readily available compounds (toluene and analogues, alkanes, ethers, ketones, etc.) as alkylating reagents, various alkyls have been implanted into the spirocycles via C(sp3)-H and Ar-NO2 bond activation with high functional group tolerance. This protocol provides a distinct method for the activation of the aryl nitro group.
- Xia, Dong,Duan, Xin-Fang
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p. 2548 - 2552
(2021/05/05)
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- Arenediazonium Tosylates (ADTs) as Efficient Reagents for Suzuki-Miyaura Cross-Coupling in Neat Water
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A simple, convenient, and environment-friendly procedure for the preparation of substituted biaryls via Suzuki-Miyaura cross-coupling- was developed. The use of arenediazonium tosylates and corresponding boron compounds allows a conversion in neat water in the presence of commercially available Pd(OAc)2 under mild conditions with tolerance to a wide range of functional groups. A procedure particularly useful for the synthesis of di-ortho-substituted biaryls was developed.
- Kutonova, Ksenia V.,Jung, Nicole,Trusova, Marina E.,Filimonov, Victor D.,Postnikov, Pavel S.,Br?se, Stefan
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p. 1680 - 1688
(2017/03/21)
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- Phosphine-Free Suzuki Cross-Coupling Reaction Using an Efficient and Reusable Pd Catalyst in an Aqueous Medium under Microwave Irradiation
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We report here an improved, highly efficient, and general method for the ligand-free Suzuki cross-coupling reaction to the synthesis of biaryls, bipyridyls, thienylpyridine, and allylphenols. Microwave irradiation of (het)aryl halides and (hetaryl, allyl)arylboronic acid N-methyl-iminodiacetic acid (MIDA) ester, using polyurea microencapsulated palladium catalyst (Pd EnCat 30), gave the coupling adducts 1a-x in excellent yields in just 10-18 min.
- Da Silva, Joaquim F. M.,Yepes Perez, Andres F.,De Almeida, Natália P.
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supporting information
p. 1995 - 2004
(2015/08/18)
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- Catalytic oxidative cyclization of 2′-arylbenzaldehyde oxime ethers under photoinduced electron transfer conditions
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A series of 2′-arylbenzaldehyde oxime ethers were synthesized and shown to generate the corresponding phenanthridines upon irradiation in the presence of 9,10-dicyanoanthracene in acetonitrile. Mechanistic studies suggest that the oxidative cyclization reaction sequence is initiated by an electron transfer step followed by nucleophilic attack of the aryl ring onto the nitrogen of the oxime ether. A concave downward Hammett plot is presumably the result of a change in charge distribution in the radical cation species with strongly electron-donating substituents that yields a less electrophilic nitrogen atom and a decreased amount of cyclized product. The reaction is selective (no nitrile byproduct is formed unlike other photochemical reactions involving aldoxime ethers) as well as regiospecific when using 2′-aryl groups with metasubstituents, making this reaction a useful alternative for preparing substituted phenanthridines.
- Hofstra, Julie L.,Grassbaugh, Brittany R.,Tran, Quan M.,Armada, Nicholas R.,De Lijser, H. J. Peter
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p. 256 - 265
(2016/09/09)
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- An efficient and new protocol for phosphine-free Suzuki coupling reaction using palladium-encapsulated and air-stable MIDA boronates in an aqueous medium
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A simple methodology that uses a system based on polyurea microencapsulated palladium (PdEnCat 30) and aryl or (2-pyridyl) MIDA boronates for Suzuki-Miyaura cross-coupling reactions of (hetero)aryl halides in water-alcohol under phosphine-free conditions was developed. This journal is the Partner Organisations 2014.
- Mendes Da Silva, Joaquim Fernando,Yepes Perez, Andres Felipe,Pinto De Almeida, Natalia
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p. 28148 - 28155
(2014/07/21)
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- [Pd(Cl)2(P(NC5H10)(C6H 11)2)2] - A highly effective and extremely versatile palladium-based negishi catalyst that efficiently and reliably operates at low catalyst loadings
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[Pd(Cl)2(P(NC5H10)-(C6H 11)2]2] (1) has been prepared in quantitative yield by reacting commercially available [Pd(cod)(Cl)2] (cod = cyclooctadiene) with readily prepared 1-(dicyclohexylphosphanyl)piperidine in toluene under N2 within a few minutes at room temperature. Complex 1 has proved to be an excellent Negishi catalyst, capable of quantitatively coupling a wide variety of electronically activated, non-activated, deactivated, sterically hindered, heterocyclic, and functionalized aryl bromides with various (also heterocyclic) arylzinc reagents, typically within a few minutes at 100°C in the presence of just 0.01 mol% of catalyst. Aryl bromides containing nitro, nitrile, ether, ester, hydroxy, carbonyl, and carboxyl groups, as well as acetais, lactones, amides, anilines, alkenes, carboxylic acids, acetic acids, and pyridines and pyrimidines, have been successfully used as coupling partners. Furthermore, electronic and steric variations are tolerated in both reaction partners. Experimental observations strongly indicate that a molecular mechanism is operative.
- Bolliger, Jeanne L.,Frech, Christian M.
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experimental part
p. 11072 - 11081
(2010/11/16)
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- Arylene imine macrocycles of C3h and C3 symmetry from reductive imination of nitroformylarenes
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(Chemical Equation Presented) Novel C3-symmetric phenylene imine macrocycles have been synthesized by reductive imination of single nitroformylarenes. Pore size and geometric shape are dictated by the distance between and orientation of thei nitro and aldehyde moieties in the precursor backbone. This reaction is facile, requires no purification of the products, and is environmentally friendly.
- Korich, Andrew L.,Hughes, Thomas S.
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supporting information; experimental part
p. 5405 - 5408
(2009/06/20)
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- An aryl to imidoyl palladium migration process involving intramolecular C-H activation
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Biologically interesting fluoren-9-one and xanthen-9-one derivatives have been prepared by a novel aryl to imidoyl palladium migration, followed by intramolecular arylation. The fluoren-9-one synthesis appears to involve both a palladium migration mechanism and a C-H activation process proceeding through an unprecedented organopalladium(IV) hydride intermediate. The results from deuterium labeling experiments are consistent with the proposed dual mechanism.
- Zhao, Jian,Yue, Dawei,Campo, Marino A.,Larock, Richard C.
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p. 5288 - 5295
(2008/02/02)
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