865138-52-9Relevant academic research and scientific papers
Bis(pyrazolyl)palladium(II) complexes as catalysts for Mizoroki–Heck cross-coupling reactions
Ocansey, Edward,Darkwa, James,Makhubela, Banothile C.E.
, p. 52 - 59 (2019)
Recent progress in carbon–carbon cross-coupling reactions has resulted in the discovery of highly active catalysts for carrying out such transformations. However, due to the wide array of applications of the products from cross-coupling reactions, there is the need to design suitable catalysts that permit the practical and economical synthesis of the cross-coupled products. Palladium complexes with bulky and electron-donating ligands have served as excellent (pre)catalysts for the Mizoroki–Heck cross-coupling reaction. By using bulky pyrazole-based ligands, we have prepared palladium(II) complexes with controlled steric and electronic properties of the metal center. We have used these bulky bis(pyrazolyl)palladium(II) complexes as (pre)catalysts for the Mizoroki–Heck cross-coupling reaction. The (pre)catalysts displayed high activity and selectivity, giving high catalytic conversions at a low (pre)catalyst loading and short reaction times. A mercury poisoning test confirmed that the (pre)catalysts promoted the Mizoroki–Heck cross-coupling homogenously and do not decompose into palladium black during the reactions. The catalytic systems were also tolerant to the presence of functional groups, such as 4-CF3, 4-CH3, 4-CO2Me and 4-CO2Et, on the alkene substrates.
Synthesis, characterization and evaluation of bulky bis(pyrazolyl)palladium complexes in Suzuki-Miyaura cross-coupling reactions
Ocansey, Edward,Darkwa, James,Makhubela, Banothile C. E.
, p. 13826 - 13834 (2018/04/26)
Pyrazole-containing compounds have been used in recent times as ligands to stabilize metal complexes used as pre-catalysts in cross-coupling reactions. With various substituents at various positions in the pyrazole ring, the overall electrophilic and steric properties of the metal complexes can be fine-tuned. Herein, we report the synthesis of bulky pyrazole-based ligands by condensation of methyl 4-(bromomethyl)benzoate or benzyl bromide with various substituted pyrazole compounds. These ligands were utilised in the synthesis of bis(pyrazolyl)palladium(ii) complexes. The complexes' catalytic activity in Suzuki-Miyaura cross-coupling reactions was evaluated. Phenyl bearing pre-catalyst 7, at a catalyst loading of 0.33 mol%, successfully converted 98% of bromobenzene and phenylboronic acid to biphenyl in 4 h at 140 °C, while the tertiary butyl bearing pre-catalyst 8 converted up to 81% of the same substrates to biphenyl. An increase in conversion was seen for all pre-catalysts when an electron-withdrawing substituent was present on the aryl halide substrate, and the opposite was observed when the electron-withdrawing group was present on the phenyl boronic acid.
AMINOPHENYLPROPANOIC ACID DERIVATIVE
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Page/Page column 83, (2010/11/24)
A compound represented by the formula (1): wherein each symbol is as defined in the specification, and a salt thereof and a prodrug thereof unexpectedly have superior GPR40 receptor agonist activity, superior in the properties as a pharmaceutical product such as stability and the like, and can be a safe and useful pharmaceutical agent as a drug for the prophylaxis or treatment of GPR40 receptor related pathology or diseases such as diabetes and the like.
