- A Convoluted Polyvinylpyridine-Palladium Catalyst for Suzuki-Miyaura Coupling and C?H Arylation
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The development of highly active and reusable supported catalysts for Suzuki-Miyaura coupling and catalytic C?H arylation is important for fundamental and applied chemistry, with these reactions being used to produce medical compounds and functional materials. Herein, we found that a mesoporous composite made of a linear poly(4-vinylpyridine) and tetrachloropalladate acted as a dual-mode catalyst for a variety of cross-coupling reactions, with both Pd nanoparticles and a Pd complex catalyst being observed under different conditions. The polyvinylpyridine-palladium composite 1 was readily prepared via the molecular convolution of poly(4-vinylpyridine) and sodium tetrachloropalladate to provide a hardly soluble polymer-metal composite. The Suzuki-Miyaura coupling and the C?H arylation of aryl chlorides and bromides with arylboronic acids, thiophenes, furans, benzene, and anisole proceeded in the presence of 0.004 mol% (40 mol ppm) to 1 mol% Pd of 1 to afford the corresponding coupling products in high yields. Furthermore, the catalyst was reused without an appreciable loss of activity. Pharmaceutical compounds and functional materials were synthesized via the coupling reactions. N2 gas adsorption/desorption analysis indicated that the catalyst had a mesoporous nature, which played a crucial role in the catalysis. In the Suzuki-Miyaura couplings, in situ generated palladium nanoparticles in the polymer matrix were catalytically active, while a polymeric Pd(II) complex was crucial in the C?H arylations. These catalytic species were investigated via XAFS, XPS, far-infrared absorption, and Raman spectroscopies, as well as DFT calculations. (Figure presented.).
- Ohno, Aya,Sato, Takuma,Mase, Toshiaki,Uozumi, Yasuhiro,Yamada, Yoichi M. A.
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supporting information
p. 4687 - 4698
(2020/09/07)
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- Aryl trihydroxyborates: Easily isolated discrete species convenient for direct application in coupling reactions
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A conceptually and practically simple alternative approach to the use of arylboron species as the organometallic component in cross-coupling processes is described whereby trihydroxyborate salts are isolated and directly employed. The protocol derives practical benefit from the ease and convenience of the isolation and subsequent use of the discrete borate salts, eliminates the need for additional base, and aids the use of correct reaction stoichiometry.
- Cammidge, Andrew N.,Goddard, Victoria H. M.,Gopee, Hemant,Harrison, Nicola L.,Hughes, David L.,Schubert, Christopher J.,Sutton, Benjamin M.,Watts, Gary L.,Whitehead, Andrew J.
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p. 4071 - 4074
(2007/10/03)
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- New Liquid Crystalline Compounds Based on Thiophene
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A homologous series of 2-alkyl-5-(4'-cyanophenyl)thiophenes has been prepared and shown to have improved properties for use in liquid crystal displays.The thiophene ring is prepared from a 1-(4'-bromophenyl)-1,4-dioxoalkane, constructed using the Stetter procedure, by the action of Lawessons reagent, and the cyano-group is finally introduced using a copper(I)-mediated exchange reaction.
- Brettle, Roger,Dunmur, David A.,Marson, Charles M.,Pinol, Milagros,Toriyama, Kazuhisa
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p. 613 - 616
(2007/10/02)
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