1665-41-4Relevant articles and documents
Photoinduced Substitution Reactions in Halothiophene Derivatives. Steady State and Laser Flash Photolytic Studies
Elisei, F.,Latterini, L.,Aloisi, G. G.,D'Auria, M.
, p. 5365 - 5372 (1995)
A photochemical and photophysical study by steady state and pulsed techniques of 5-bromo- and 5-iodo-2-thiophenecarbaldehyde and 2-acetyl-5-iodothiophene in benzene is presented.The quantum yields for the direct and sensitized formation of the phenylthiophenes following the photocleavage of the carbon-halogen bond were determined in the 293-343 K temperature range.The transient species (triplets and free radicals) originated by laser excitation were investigated by laser flash photolysis; their spectral and kinetic properties and their formation quantum yields were determined at room temperature.The halogen atoms were detected through their interactions with teh solvent to form benzene-X. complexes that were identified by absorption spectra and decay lifetimes.The characteristics of the triplets were also determined in methylcyclohexane/3-methylpentane (9:1, v/v) at 77 K.Phosphorescence measurements at low temperature gave the spectral and kinetic characteristics of the lowest triplet states of halothiophenes.Through the effect of the solvent polarity on the triplet energy (ET), evidence was obtained of the n,?* nature of the lowest triplet.Results obtained by steady state and pulsed techniques gave strong indication that the sensitized photosubstitution takes place through an upper triplet state (likely ?,?* in nature) localized on the carbon-halogen bond.A scheme showing the energies of the involved electronic states is presented.For the direct photoreaction the main route is probably the triplet again, although a singlet pathway cannopt be excluded.
Reusable, polymer-supported, palladium-catalyzed, atom-efficient coupling reaction of aryl halides with sodium tetraphenylborate in water by focused microwave irradiation
Bai, Lin,Wang, Jin-Xian
, p. 315 - 320 (2008)
A rapid and efficient cross-coupling reaction of sodium tetraphenylborate with aryl bromides was carried out in water at 120°C in the presence of a polymer-supported palladium catalyst and potassium carbonate under focused microwave irradiation. All four phenyl groups of sodium tetraphenylborate participated in the reaction and produced polyfunctional biaryls in excellent yields. The polymeric catalyst can be easily separated from the reaction mixture and reused more than 10 times without showing any decrease in activity.
The first use of [PdBr2(imidazolidin-2-ylidene)(pyridine)] catalysts in the direct C-H bond arylation of C2-substituted furan and thiophene
Kalo?lu, Murat,Kalo?lu, Nazan,?zdemir, Nam?k,?zdemir, ?smail
, p. 2821 - 2843 (2021/04/21)
Abstract: N-Heterocyclic carbene (NHC)-linked PEPPSI-type palladium complexes have recently been used in the direct C-H bond arylation of heteroarenes. However, in most of the published works, NHC ligands containing benzimidazole and imidazole ring have b
1,3-Dioxane Functionalized Pd-PEPPSI Catalyst for Direct Arylation of Heteroaromatics
Ulu, ?znur Do?an
, (2021/08/09)
A series of benzimidazolium salts (1a-d) and their Pd-PEPPSI complexes (pyridine-enhanced precatalyst preparation, stabilization, and initiation) (2a-d) were prepared to catalyze the direct arylation of heteroaromatics (2-acetylthiophene and 2-furaldehyde) with various aryl bromides. The structures of all isolated compounds were elucidated based on spectroscopic methods (1H and 13C NMR, FT-IR and LC-MS spectroscopy). Under optimized reaction conditions, C5-arylated products were obtained in moderate to excellent yields in the direct arylation of heteroaromatics.