334977-38-7Relevant academic research and scientific papers
Electron-rich trialkyl-type dihydro-KITPHOS monophosphines: Efficient ligands for palladium-catalyzed suzuki-miyaura cross-coupling. Comparison with their biaryl-like KITPHOS monophosphine counterparts
Doherty, Simon,Knight, Julian G.,Ward, Nicholas A. B.,Bittner, Dror M.,Wills, Corinne,McFarlane, William,Clegg, William,Harrington, Ross W.
supporting information, p. 1773 - 1788 (2013/05/08)
The Diels-Alder cycloaddition between dicyclohexylvinylphosphine oxide and anthracene or 9-methylanthracene affords the bulky electron-rich trialkyl-type dihydro-KITPHOS monophosphines 11-(dicyclohexylphosphinoyl)-12-phenyl-9,10- dihydro-9,10-ethenoanthracene and 11-(dicyclohexylphosphinoyl)-9-methyl-12- phenyl-9,10-dihydro-9,10-ethenoanthracene, respectively, after reduction of the corresponding oxide. Both phosphines are highly air-sensitive and rapidly oxidize on silica gel during purification but have been isolated as air-stable cyclometalated palladium precatalysts of the type [Pd{κ 2N2′,C1-2-(2′-NH2C6H 4)C6H4}Cl(L)]. Both palladium precatalysts form highly active systems for the Suzuki-Miyaura cross-coupling of a range of aryl chlorides with aryl boronic acids, giving the desired products in good to excellent yield under mild conditions and a catalyst loading of 0.25 mol %. A comparison of the performance of catalysts based on dihydro-KITPHOS monophosphines against their first-generation biaryl-like KITPHOS counterparts revealed that the latter are consistently more efficient for the vast majority of substrate combinations examined, albeit by only a relatively small margin in some cases. This, together with the greater air stability and ease of handling of biaryl-like KITPHOS monophosphines, renders them more practical ligands for palladium-based cross-coupling. The steric parameters of both classes of KITPHOS monophosphine and a selection of electron-rich biaryl monophosphines have been quantified using a combination of Solid-G to determine the percentage of the metal coordination sphere shielded by the phosphine (the G parameter), and Salerno molecular buried volume calculations (SambVca) to determine the percent buried volume (%Vbur); the corresponding Tolman cone angles have also been determined from correlations and the relative merits of the two approaches discussed. The electronic properties of these phosphines have also been investigated using DFT to calculate the A1 ν(CO) frequency in LNi(CO)3 (B3LYP/6-31G(2d,p)[LanL2DZ on Ni]), and the resulting computed electronic parameters (CEP) were used to estimate the corresponding experimental Tolman electronic parameters (TEP).
Room-temperature Suzuki-Miyaura coupling of heteroaryl chlorides and tosylates
Yang, Junfeng,Liu, Sijia,Zheng, Jian-Feng,Zhou, Jianrong
supporting information, p. 6248 - 6259,12 (2020/09/16)
Suzuki-Miyaura coupling of heteroaryls is an important method for the preparation of compound libraries for medicinal chemistry and materials research. Although many catalysts have been developed, none of them have been generally applicable to the coupling reactions of heteroaryl chlorides and tosylates at room temperature. We discovered that a catalyst combination of Pd(OAc)2 and XPhos (2-dicyclohexylphosphanyl-2',4',6'- triisopropylbiphenyl) could efficiently catalyze these couplings. Besides the choice of catalyst, the use of hydroxide bases in an aqueous alcoholic solvent was essential for fast couplings. These conditions promoted fast release of active catalyst (XPhos)Pd0, and accelerated the transmetalation in the catalytic cycle. Most of the major families of heteroaryl chlorides (31 examples) and tosylates (17 examples) reached full conversion within minutes to hours at room temperature. The method could be easily scaled up for gram-scale synthesis. Furthermore, we examined the relative reactivity of coupling partners in whole reactions. Electron-rich heteroaryl chlorides and tosylates reacted more slowly than electron-deficient ones, in the order of indole, pyrrole furan, thiophene > pyridine. Similarly, electron-deficient arylboronic acids were less reactive than electron-neutral and electron-rich ones. The reactivity trends from this study can help to choose appropriate coupling partners for Suzuki reactions.
Palladium-catalyzed decarboxylative coupling of aromatic acids with aryl halides or unactivated arenes using microwave heating
Voutchkova, Adelina,Coplin, Abigail,Leadbeater, Nicholas E.,Crabtree, Robert H.
supporting information; experimental part, p. 6312 - 6314 (2009/04/13)
Microwave heating greatly accelerates Pd-catalyzed decarboxylative coupling of aromatic acids and aryl iodides, and allows the coupling of benzoic acids with unactivated arenes. The Royal Society of Chemistry 2008.
Catalysts for Suzuki-Miyaura coupling processes: Scope and studies of the effect of ligand structure
Barder, Timothy E.,Walker, Shawn D.,Martinelli, Joseph R.,Buchwald, Stephen L.
, p. 4685 - 4696 (2007/10/03)
Suzuki-Miyaura coupling reactions of aryl and heteroaryl halides with aryl-, heteroaryl- and vinylboronic acids proceed in very good to excellent yield with the use of 2-(2′,6′-dimethoxybiphenyl) dicyclohexylphosphine, SPhos (1). This ligand confers unprecedented activity for these processes, allowing reactions to be performed at low catalyst levels, to prepare extremely hindered biaryls and to be carried out, in general, for reactions of aryl chlorides at room temperature. Additionally, structural studies of various 1·Pd complexes are presented along with computational data that help elucidate the efficacy that 1 imparts on Suzuki-Miyaura coupling processes. Moreover, a comparison of the reactions with 1 and with 2-(2′,4′,6′-triisopropylbiphenyl)diphenylphosphine (2) is presented that is informative in determining the relative importance of ligand bulk and electron-donating ability in the high activity of catalysts derived from ligands of this type. Further, when the aryl bromide becomes too hindered, an interesting C-H bond functionalization-cross-coupling sequence intervenes to provide product in high yield.
Electron-deficient nitrogen heterocycle-substituted fluorescein dyes
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, (2008/06/13)
The invention provides compositions electron-deficient nitrogen heterocycle-substituted fluorescein dyes and methods in which the dyes are conjugated to substrates and used as detection labels in molecular biology experiments. The electron-deficient nitro
