19810-62-9Relevant academic research and scientific papers
Cyclopalladation in the Periphery of a NHC Ligand as the Crucial Step in the Synthesis of Highly Active Suzuki–Miyaura Cross-Coupling Catalysts
Fizia, Agnes,Gaffga, Maximilian,Lang, Johannes,Sun, Yu,Niedner-Schatteburg, Gereon,Thiel, Werner R.
, p. 14563 - 14575 (2017)
Starting from 2,4-dichloropyrimidine, 4-(2-dialkylamino)pyrimidinyl functionalized mesitylimidazolium chlorides are accessible in a five-step reaction sequence. Two routes leading to palladium NHC complexes derived from these ligands have been worked out: By transmetalation with the corresponding NHC-AgCl complexes, C,N-coordinated palladium(II) complexes can be obtained. Treatment of palladium dichloride with the imidazolium salts in pyridine and in the presence of K2CO3 gives cyclometalated and thus C,C-coordinated compounds. The reactivities of all these compounds were investigated in detail as well as their performance in the catalytic Suzuki–Miyaura cross-coupling reaction. It turned out that the C,C-coordinated derivatives exhibit high catalytic activities in the coupling of arylboronic acids with aryl chlorides, which is consistent with the generally accepted mechanistic ideas on substrate activation.
