Investigation of the catalytic activity of a Pd/biphenyl-based phosphine system in the Ullmann homocoupling of aryl bromides

Palladium-catalyzed N-arylation of 2-aminobenzothiazole-4-carboxylates/carboxamides: facile synthesis of PARP14 inhibitors

“…No homocoupling side products of aryl bromides were detected during the reaction, therefore there was no need to add extra amount of aryl bromides. 39 To further validate the established N-arylation protocol, a series of 2-aminobenzothiazole substrates containing various substituents were tested. Although it was initially concerned that the free NH in carboxamido moiety might interfere the coordination of [Pd] catalyst with substrates, 4-carboxamides 2b-2e either with an N-methyl or without N-substituents all took part in the coupling reaction smoothly and generated corresponding products 5ba-5ea in 52-66% yields ( Figure 2).…”

A Novel Recyclable Ni/Cu/Fe Termetallic Nanocatalyst for the Synthesis of Propargylamines through the A3‐Coupling Reactions

“…The NiO/OA‐CuFe 2 O 4 nanocatalyst was employed in an inexpensive and economical protocol for the A 3 ‐coupling reaction of aldehydes, amines, and terminal alkynes. The proposed procedure was very easy, and involved many advantages such as (I) using Ni, Cu, and Fe low‐cost species instead of Pd and other precious metals such as Au and Ag, (II) good to excellent activity in the A 3 ‐coupling reaction along with the resonable selectivity, (III) easy work‐up procedure, (IV) no need to any co‐catalyst or activator in the catalytic reaction, and (V) being applicable to a wide range of substituated starting materials for synthesis of the corresponding propargylamine products with good to excellent yields. The NiO/OA‐CuFe 2 O 4 nanocatalyst could effectively be recycled up to five consecutive runs.…”

“…The interesting results were achieved in optimization of the catalyst type for the A 3 ‐coupling reaction. Using the palladium based catalysts, the reaction time to produce propargylamine was significantly reduced, but high amount of the homocoupling by‐product (diphenyl diacetylene) was obtained during reaction (Table , entries 1–3, Figure ). For example, Figure shows the propargylamine product and diphenyl diacetylene by‐product amounts for the A 3 ‐coupling reaction in the presence of Pd@Fe 3 O 4 ‐OA catalyst for 8 h. The reaction time to produce the propargylamine product increased using OA‐CuFe 2 O 4 as the catalyst, however, the amount of the homocoupling by‐product decreased (Table , entry 4).…”

Microwave Assisted Suzuki-Miyaura and Ullmann Type Homocoupling Reactions of 2- and 3-Halopyridines Using a Pd(OAc)2/Benzimidazolium Salt and Base Catalyst System

“…Bulky groups on the coupling partner also affect the catalytic yield in the Suzuki-Miyaura cross-coupling reactions [ 14 ]. The phosphine-based ligands are generally used as a ligand in this type of homocoupling reactions [ 15 , 16 , 17 , 18 , 19 , 20 , 21 , 22 , 23 , 24 ]. However tertiary phosphine ligands usually require air-free handling to prevent ligand oxidation and their P-C bond is unstable at elevated temperature, and as a consequence higher phosphine concentrations are required [ 25 ].…”