- Benzyloxycalix[8]arene supported Pd-NHC cinnamyl complexes for Buchwald-Hartwig C-N cross-couplings
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The scalable synthesis of Pd-NHC cinnamyl complexes supported on benzyloxycalix[8]arene is reported. These catalysts are very active for Buchwald-Hartwig cross-coupling reactions, allowing the coupling of aryl chlorides and bromides with a wide variety of alkyl and aryl amines using low catalytic loadings. The supported complexes also successfully afforded attractive unsymmetrical triarylamines, and in one case, promoted the synthesis of an unprecedented Pd-catalyzed C-H activation product. Thanks to the calixarenic support, the target products could be isolated with low levels of residual palladium, and in some cases, even below the restrictive toxic metal standards applied by the pharmaceutical industry. Through an easy to implement procedure, these perfectly characterised catalysts thus combine the best of homogeneous and heterogeneous catalysis: high efficiency (similar to or even better than the corresponding homogeneous complexes) and low Pd leaching levels expected from heterogeneous catalysts.
- Abi Fayssal, Sandra,Buendia, Julien,Huc, Vincent,Martini, Cyril,Naret, Timothée,Schulz, Emmanuelle
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p. 5223 - 5231
(2021/08/16)
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- Palladium Complexes Based on Ylide-Functionalized Phosphines (YPhos): Broadly Applicable High-Performance Precatalysts for the Amination of Aryl Halides at Room Temperature
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Palladium allyl, cinnamyl, and indenyl complexes with the ylide-substituted phosphines Cy3P+?C?(R)PCy2 (with R=Me (L1) or Ph (L2)) and Cy3P+?C?(Me)PtBu2 (L3) were prepared and applied as defined precatalysts in C?N coupling reactions. The complexes are highly active in the amination of 4-chlorotoluene with a series of different amines. Higher yields were observed with the precatalysts in comparison to the in situ generated catalysts. Changes in the ligand structures allowed for improved selectivities by shutting down β-hydride elimination or diarylation reactions. Particularly, the complexes based on L2 (joYPhos) revealed to be universal precatalysts for various amines and aryl halides. Full conversions to the desired products are reached mostly within 1 h reaction time at room temperature, thus making L2 to one of the most efficient ligands in C?N coupling reactions. The applicability of the catalysts was demonstrated for aryl chlorides, bromides and iodides together with primary and secondary aryl and alkyl amines, including gram-scale applications also with low catalyst loadings of down to 0.05 mol %. Kinetic studies further demonstrated the outstanding activity of the precatalysts with TOF over 10.000 h?1.
- Tappen, Jens,Rodstein, Ilja,McGuire, Katie,Gro?johann, Angela,L?ffler, Julian,Scherpf, Thorsten,Gessner, Viktoria H.
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supporting information
p. 4281 - 4288
(2020/03/13)
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- Copper-catalyzed N- tert -butylation of aromatic amines under mild conditions using tert -butyl 2,2,2-trichloroacetimidate
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A variety of aromatic amines have been found to expediently undergo copper-catalyzed N-tert-butylation in the presence of tert-butyl 2,2,2-trichloroactimidate at room temperature. Georg Thieme Verlag Stuttgart New York.
- Cran, John W.,Vidhani, Dinesh V.,Krafft, Marie E.
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p. 1550 - 1554
(2014/07/08)
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- The synthesis of mauveine A and mauveine B from N-tert-butyl-p-toluidine
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The oxidation of a mixture of N-tert-butyl-p-toluidine/aniline/o-toluidine (1 : 1.5 : 1.5) with K2Cr2O7 in H +/H2O followed by de-tertbutylation with acid gives mauveine A and mauveine B. These compounds dye silk the same shade of red mauve as that of silk dyed by authentic mauveine.
- Plater, M. John
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p. 163 - 168
(2014/04/17)
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- Efficient catalytic aryl amination of bromoarenes using 3-iminophosphine palladium(II) chloride
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While pursuing the development of new hydroamination catalysts, a 3-iminophosphine palladium(II) chloride complex [(3IP)PdCl2] was synthesized that has subsequently proven to be an effective precatalyst for the aryl amination of bromoarenes. This (3IP)PdCl2 complex has been utilized in the catalytic aryl amination of both bromobenzene and bromopyridine derivatives, specifically yielding excellent activity in coupling reactions involving bromobenzene, 4-bromotoluene, and 2-bromopyridine. Using a standard set of catalytic conditions, many alkyl and aryl amines have been investigated as coupling partners in the aryl amination of bromoarenes. In general, secondary alkyl amines and ortho-substituted anilines proved to be the best substrates for this reaction, commonly giving quantitative conversion to products, while primary amines and other anilines gave only poor to moderate results. Catalytic screening data, product yields, and full characterization of isolated products are included.
- Samblanet, Danielle C.,Schmidt, Joseph A. R.
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p. 7 - 18,12
(2012/12/12)
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- Microwave-promoted mono-N-alkylation of aromatic amines in water: A new efficient and green method for an old and problematic reaction
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A greener improvement to direct mono-N-alkylation of aromatic amines by alkyl halides was achieved using microwave irradiation in water without any catalyst.
- Marzaro, Giovanni,Guiotto, Adriano,Chilin, Adriana
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supporting information; experimental part
p. 774 - 776
(2010/04/23)
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- Photochemical Reactions of Substituted Benzenes with Aliphatic Amines
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The products arising from the irradiation of diethylamine and t-butylamine with toluene, chlorobenzene, anisole, benzonitrile, benzyl fluoride, benzotrifluoride (α,α,α-trifluorotoluene), m-fluorobenzotrifluoride (α,α,α,m-tetrafluorotoluene), p-fluorotoluene, m-fluorotoluene, p-fluoroanisole, m-fluoroanisole, and 1,3-bis(trifluoromethyl)benzene, and of triethylamine with toluene, benzotrifluoride and 1,3-bis(trifluoromethyl)benzene, all at 254 nm, are described.Reaction pathways involving both substitution and 1,2- and 1,4-acyclic addition processes are observed and which predominates depends upon the arene substituent.The novel acyclic adduct, Me2C=CH-CH=CH-CH=NBut, is obtained from toluene and t-butylamine and, contrary to previous reports, chlorobenzene yields arene-amine 1:1 adducts as well as the amine α-substitution product (16); benzonitrile gives aniline derivatives with the primary and secondary amines.
- Gilbert, Andrew,Krestonosich, Stefan,Westover, David L.
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p. 295 - 302
(2007/10/02)
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