An efficient 2-(2-Pyridyl)imidazole based copper catalyst for N-Arylation of N-heterocycles

• Published in: Molecular catalysis 2023-07, Vol.545, p.113212, Article 113212
• Main Authors: Sarkar, Gayetri, Bandopadhyay, Nilaj, Paramanik, Krishnendu, Saha, Subhajit, Panda, Subhra Jyoti, Purohit, Chandra Shekhar, Biswas, Bhaskar, Das, Hari Sankar
• Format: Article
• Language: English
• Subjects: 2-(2′-Pyridyl)-Imidazole; Aryl halides; Copper catalyst; Cross-Coupling Reactions; Homogeneous catalysis
• ISSN: 2468-8231; 2468-8231
• DOI: 10.1016/j.mcat.2023.113212

•Structural and electrochemical characterization of a copper(II)-pyridyl-imidazole complex.•Shows an excellent catalytic activity towards N-arylation of N-heterocycles.•The reduced form of the present catalyst is more reactive than corresponding copper(II)-phenanthroline complex. An earth-abundant copper based 2-(2-pyridyl)imidazole (L) complex of the type [CuL2(NO3)](NO3), (1) has been characterized spectroscopically, structurally and electrochemically. The copper(II) in 1 is present in a distorted trigonal-bipyramidal coordination environment and has structural similarity with the well-known 1,10-phenanthroline (L′) coordinated copper catalytic system used in Ullmann-type N-arylation reactions. Complex 1 is more electronically rich than the corresponding 1,10-phenanthroline-based complex, [CuL′2(NO3)](NO3), (2) and shows excellent catalytic activity towards N-arylation of nitrogen heterocycles like pyrazole, imidazole, benzimidazole and less reactive indole with aryl-iodides and -bromides. Electronically deficient aryl-chlorides are also successful as a coupling agent for N-arylation with good yields. Wide spectrums of common organic functional groups are also tolerated in our catalytic conditions. A possible mechanistic route for this N-arylation reaction has been proposed by considering several experimental and spectroscopic results along with computational details. [Display omitted]