Synthesis of palladium complexes containing benzimidazole core and their catalytic activities in direct arylation of heteroaromatic species

Abstract

Herein, we report the synthesis of four new palladium complexes containing a benzimidazole core and examine their catalytic activities in the direct arylation of heteroaromatic species with aryl bromides. The complexes were characterized by ¹H and ¹³C NMR spectroscopy, FT-IR spectroscopy, and elemental analysis. In the ¹³C NMR spectra, NCHN peaks of Pd(II) complexes were observed between 143.2 and 144.9 ppm. Also, the structure of 2b was determined by single-crystal XRD analysis. The obtained data suggest that the lengths of the Pd–N and Pd–Cl bonds are like those of previous Pd complexes. Direct arylation reactions, using KOAc as base and DMAc as solvent under inert conditions, were carried out with the synthesized complexes in the presence of various aryl bromides, and 2-acetylthiophene, 2-furaldehyde, and 1-methylpyrole-2-carboxaldehyde. Moderate to high yields were obtained under 1% mol catalyst loading conditions. The results showed that electron-donating and electron-withdrawing substituents on the aryl halides may produce coupling products in good yields in the presence of 2a–d. These findings contribute to the synthesis and design of palladium complexes containing benzimidazole cores.

Keywords:

• Palladium complexes
• azole
• direct arylation
• catalytic activity

Acknowledgments

This study was supported by the Scientific Research Projects Unit of Ondokuz Mayıs University (Project No: PYO.FEN.1906.19.001).

Supplementary data

CCDC 2249969 contains the supplementary crystallographic data for the compound reported in this article. These data can be obtained free of charge on application to CCDC, 12 Union Road, Cambridge CB2 1EZ, UK [Fax: [phone]; E-mail: [email protected]; https://www.ccdc.cam.ac.uk/structures/].

Disclosure statement

No potential conflict of interest was reported by the authors.