Three copper(II) complexes derived from 2‐methylquinoline and cyclic secondary amines: Synthesis and catalytic application in C—N bond forming reactions

Abstract Three copper(II) complexes ( I – III ) bearing N , O ‐bidentate ligands ( L 1 – L 3 ), derived from 2‐methylquinoline and cyclic secondary amines (including pyrrolidine, morpholine, and 4‐methylpiperidine), were successfully prepared and successively employed in construction of CN bonds via the Chan–Lam coupling of 1 H ‐imidazole derivatives with arylboronic acids. X‐ray diffraction analysis demonstrated that the central copper(II) atom of II adopted the distorted tetrahedral geometry, which was four coordinated by one nitrogen atom and one oxygen atom from L 2 as well as two chloride atoms. Catalytic studies indicated that complex II displayed higher activity in Chan–Lam reaction than complex I or III . The present protocol for N , O ‐coordinated‐copper complex‐catalyzed CN coupling reaction exhibited some advantages such as wide scope of substrates, good yields, and mild conditions.