26191-64-0Relevant articles and documents
Preparation of metal-immobilized methacrylate-based monolithic columns for flow-through cross-coupling reactions
Sabarudin, Akhmad,Shu, Shin,Umemura, Tomonari,Yamamoto, Kazuhiro
, (2021/12/17)
With the aim of developing efficient flow-through microreactors for high-throughput organic synthesis, in this work, microreactors were fabricated by chemically immobilizing palladium-, nickel-, iron-, and copper-based catalysts onto ligand-modified poly(glycidyl methacrylate-co-ethylene dimethacrylate) [poly(GMA-co-EDMA)] monoliths, which were prepared inside a silicosteel tubing (10 cm long with an inner diameter of 1.0 mm) and modified with several ligands including 5-amino-1,10-phenanthroline (APHEN), iminodiacetic acid (IDA), and iminodimethyl phosphonic acid (IDP). The performance of the resulting microreactors in Suzuki?Miyaura cross-coupling reactions was evaluated, finding that the poly(GMA-co-EDMA) monolith chemically modified with 5-amino-1,10-phenanthroline as a binding site for the palladium catalyst provided an excellent flow-through performance, enabling highly efficient and rapid reactions with high product yields. Moreover, this monolithic microreactor maintained its good activity and efficiency during prolonged use.
An alternative approach to para-C-H arylation of phenol: Palladium-catalyzed tandem γ-arylation/aromatization of 2-cyclohexen-1-one derivatives
Imahori, Tatsushi,Tokuda, Toru,Taguchi, Tatsuya,Takahata, Hiroki
supporting information; scheme or table, p. 1172 - 1175 (2012/04/04)
An efficient approach to prepare para-aryl phenols has been developed by using a Pd-catalyzed tandem γ-arylation/aromatization of 2-cyclohexen-1-one derivatives with aryl bromides. This approach provides various p-aryl phenols from the phenol surrogates, 2-cyclohexen-1-one derivatives, in a single reaction step on the basis of C-H arylation.
Characterization of reactive intermediates generated during photolysis of 4-acetoxy-4-aryl-2,5-cyclohexadienones: Oxenium ions and aryloxy radicals
Wang, Yue-Ting,Jin, Kyoung Joo,Leopold, Samuel H.,Wang, Jin,Peng, Huo-Lei,Platz, Matthew S.,Xue, Jiadan,Phillips, David Lee,Glover, Stephen A.,Novak, Michael
experimental part, p. 16021 - 16030 (2009/05/16)
Aryloxenium ions 1 are reactive intermediates that are isoelectronic with the better known arylcarbenium and arylnitrenium ions. They are proposed to be involved in synthetically and industrially useful oxidation reactions of phenols. However, mechanistic studies of these intermediates are limited. Until recently, the lifetimes of these intermediates in solution and their reactivity patterns were unknown. Previously, the quinol esters 2 have been used to generate 1, which were indirectly detected by azide ion trapping to generate azide adducts 4 at the expense of quinols 3, during hydrolysis reactions in the dark. Laser flash photolysis (LFP) of 2b in the presence of O2 in aqueous solution leads to two reactive intermediates with γmax 360 and 460 nm, respectively, while in pure CH3CN only one species with λmax 350 nm is produced. The intermediate with Amax 460 nm was previously identified as lb based on direct observation of its decomposition kinetics in the presence of N3-, comparison to azide ion trapping results from the hydrolysis reactions, and photolysis reaction products (3b). The agreement between the calculated (B3LYP/6-31G(d)) and observed time-resolved resonance Raman (TR3) spectra of 1b further confirms its identity. The second intermediate with λ max 360 nm (350 nm in CH3CN) has been characterized as the radical 5b, based on its photolytic generation in the less polar CH 3CN and on isolated photolysis reaction products (6b and 7b). Only the radical intermediate 5b is generated by photolysis in CH3CN, so its UV-vis spectrum, reaction products, and decay kinetics can be investigated in this solvent without interference from 1b. In addition, the radical 5a was generated by LFP of 2a and was identified by comparison to a published UV-vis spectrum of authentic 5a obtained under similar conditions. The similarity of the UV-vis spectra of 5a and 5b, their reaction products, and the kinetics of their decay confirm the assigned structures. The lifetime of 1b in aqueous solution at room temperature is 170 ns. This intermediate decays with first-order kinetics. The radical intermediate 5b decomposes in a biphasic manner, with lifetimes of 12 and 75 μs. The decay processes of 5a and 5b were successfully modeled with a kinetic scheme that included reversible formation of a dimer. The scheme is similar to the kinetic models applied to describe the decay of other aryloxy radicals.
