Pd-PEPPSI complexes based on 1,2,4-triazol-3-ylidene ligands as efficient catalysts in the Suzuki—Miyaura reaction

Base‐Ionizable Anionic NHC Ligands in Pd‐catalyzed Reactions of Aryl Chlorides

“…The molecular geometries of complexes 9 f , 9 m and 9 n are similar to the geometries of complexes with Nitron‐type NHC ligands and pyridine coligands described in the literature [12g,h] . The Pd‐C (NHC) bond lengths (1.957(6)–1.9683(9) Å) in compounds 9 f , 9 m and 9 n are very close to the length of the same bond (1.945–1.988 Å) in Pd/NHC complexes with common 1,2,4‐triazole and imidazole NHC ligands [21,23] …”

“…Proligands 4 , 7 and 8 were successfully palladated by PdCl 2 in pyridine or 3‐chloropyridine in the presence of K 2 CO 3 to give Pd/NHC complexes 9 a – n and 10 (Scheme 2). In the synthesis of complex 9 e from bromide salt 7 j and PdCl 2 , the formation of a mixture of complexes with chloride and bromide coligands may be anticipated [21] . Therefore, tetrabutylammonium bromide was used as an additive to provide an excess concentration of bromide anions and shift the reaction to dibromide complex 9 e .…”

“…[12g,h] The Pd-C (NHC) bond lengths (1.957(6)-1.9683(9) Å) in compounds 9 f, 9 m and 9 n are very close to the length of the same bond (1.945-1.988 Å) in Pd/NHC complexes with common 1,2,4-triazole and imidazole NHC ligands. [21,23] Catalytic activity studies Initially, we studied the effect of the NHC ligand structure on catalytic activity using Suzuki-Miyaura cross-coupling between 4-chlorotoluene (12 a) and phenylboronic acid (13 a) as a model reaction (Tables 1 and S2). Catalytic systems generated in situ from proligands 4 a-m, 7 a-n, and 8 and palladium acetate (palladium acetate was used instead of palladium chloride due to its better solubility in dioxane) as well as well-defined complexes 9 a-n were evaluated in the model reaction (Tables 1 and S2).…”

“…In the synthesis of complex 9 e from bromide salt 7 j and PdCl 2 , the formation of a mixture of complexes with chloride and bromide coligands may be anticipated. [21] Therefore, tetrabutylammonium bromide was used as an additive to provide an excess concentration of bromide anions and shift the reaction to dibromide complex 9 e.…”

Synthetic approach for the control of self-doping in luminescent organic semiconductors

“…The first pathway starts from Suzuki cross-coupling of (4-octylphenyl)boronic acid ( 1 Ligand exchange between a boronic acid moiety and a bromine moiety is a well-known side-reaction in Pd-catalyzed Suzuki crosscoupling. 41,78,79 The possible by-products formed in the coupling reaction during the preparation of batch I are 1-bromo-4-octylbenzene and (5-formylthiophene-2-yl)boronic acid. These compounds can react further consequently forming short-chain 4,4 0dioctyl-1,1 0 -biphenyl and [2,2 0 -bithiophene]-5,5 0 -dicarbaldehyde which can be easily removed by a column chromatography since they are not structurally close to the main product.…”