A Mixed N-Heterocyclic Carbene/Triphenylphosphine Palladium(II) Complex for Suzuki-Miyaura Cross-Coupling Reactions
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2021
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Abstract
In this work, a novel compound, 1-(2,5-dimethylbenzyl)benzimidazole (1) was prepared by N- alkylation of benzimidazole with 2,5-dimethylbenzyl chloride in the presence of KOH base. Quaternization of 1 with 2,5-dimethylbenzyl chloride gave 1,3-bis(2,5- dimethylbenzyl)benzimidazolium chloride (2) salt. The reaction of 2 with palladium(II) acetate, PPh3, LiCl and Et3N gave [PdCl2{1,3-bis(2,5-dimethylbenzyl)benzimidazolin-2-ylidene}(PPh3)] (3) complex. The prepared compounds were characterized by spectroscopic methods and elemental analysis. The palladium complex 3 was used as catalyst in Suzuki–Miyaura cross-coupling reactions of some aryl bromides and chlorides with phenylboronic acid. In the reactions of the all aryl bromides, the catalyst displayed excellent activity and biphenyl compounds were achieved in 99% yields. High activity was observed with some aryl chlorides.