87109-10-2Relevant articles and documents
Tetrabutylphosphonium 4-ethoxyvalerate as a biomass-originated media for homogeneous palladium-catalyzed Hiyama coupling reactions
Orha, László,Papp, ábrahám,Tukacs, József M.,Kollár, László,Mika, László T.
, p. 4593 - 4598 (2020/07/28)
The introduction of a biomass-derived ionic liquid into the Hiyama coupling reactions, which has been considered as a powerful tool for the synthesis of symmetrically and non-symmetrically substituted biaryl structures, could further control or even reduce the environmental impact of this transformation. It was shown that tetrabutylphosphonium 4-ethoxyvalerate, a γ-valerolactone-based ionic liquid, can be utilized as an alternative solvent to create carbon–carbon bonds between aryl iodides and functionalized organosilanes in the presence of 1?molpercent Pd under typical Hiyama conditions (130?°C, 24?h, tetrabutylammonium fluoride activator). A comparison of different ionic liquids was performed, and the effects of the catalyst precursor and the moisture content of the reaction mixture on the activity of the catalyst system were investigated. The functional group tolerance was also studied, resulting in 15 cross-coupling products (3a–o) with isolated yields of 45–72percent and excellent purity (' 98percent).
Pd-Catalyzed Suzuki coupling reactions of aryl halides containing basic nitrogen centers with arylboronic acids in water in the absence of added base
Li, Zhao,Gelbaum, Carol,Campbell, Zachary S.,Gould, Paul C.,Fisk, Jason S.,Holden, Bruce,Jaganathan, Arvind,Whiteker, Gregory T.,Pollet, Pamela,Liotta, Charles L.
supporting information, p. 15420 - 15432 (2017/12/15)
The Pd-catalyzed Suzuki coupling reactions of a series of aryl chlorides and aryl bromides containing basic nitrogen centers with arylboronic acids in water in the absence of added base are reported. The reactions proceed either partially or entirely under acidic conditions. After surveying twenty-two phosphorus ligands, high yields of products were obtained with aryl chlorides only when a bulky ligand, 2-(di-tert-butyl-phosphino)-1-phenyl-1H-pyrrole (cataCXiumPtB) was used. In contrast, aryl bromides produced high yields of products in the absence of both added base and added ligand. In order to explore the Suzuki coupling process entirely under acidic conditions, a series of reactions were conducted in buffered acidic media using several model substrates. 4-Chlorobenzylamine, in the presence of cataCXiumPtB, produced high yields of product at buffered pH 6.0; the yields dropped off precipitously at buffered pH 5.0 and lower. The fall-off in yield was attributed to the decomposition of the Pd-ligand complex due to the protonation of the ligand in the more acidic aqueous media. In contrast, in the absence of an added ligand, 4-amino-2-chloropyridine produced quantitative yields at buffered pH 3.5 and 4.5 while 4-amino-2-bromopyridine produced quantitative yields in a series of buffered media ranging from pH 4.5 to 1.5. These substrates are only partially protonated in acidic media and can behave as active Pd ligands in the Suzuki catalytic cycle.
METHODS FOR EXTERNAL BASE-FREE SUZUKI COUPLINGS
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Paragraph 0035-0036, (2017/07/14)
The present disclosure describes a method of coupling a first aromatic compound to a second aromatic compound, the method comprising: (a) preparing a reaction mixture comprising the first aromatic compound, the second aromatic compound, a catalyst and water; the reaction mixture does not contain an external base, the reaction mixture having an initial pH of from 11 to 1; the catalyst having at least one group 10 atom; the first aromatic compound having a halogen, triflate or sulfonate substituent; the second aromatic compound having a boron-containing substituent; wherein, at least one of the first aromatic compound or the second aromatic compound includes one or more heteroatom; and (b) reacting the first aromatic compound and the second aromatic compound in the reaction mixture, the reaction mixture having a final pH following reaction of the first aromatic compound and the second aromatic compound.
