Chan–Lam cross-coupling reactions promoted by anionic copper(I)/iodide species with cationic methyl-((pyridinyl)-pyrazolyl)pyridin-1-ium

Four anionic ligands including 1-methyl-3(or 4)-(1-(pyridin-2-yl)-1H-pyrazol-3-yl)pyridin-1-ium iodide ([3,2′-pypzpym]I, [4,2′-pypzpym]I) and 1-methyl-3(or 4)-(3-(pyridin-2-yl)-1H-pyrazol-1-yl)pyridin-1-ium iodide ([2,3′-pypzpym]I, [2,4′-pypzpym]I) are prepared. Reaction of CuI with [3,2′-pypzpym]I affords a mononuclear complex [CuI2(3,2′-pypzpym)] (1) and a one-dimensional coordination polymer [(Cu4I6)(3,2′-pypzpym)2]n (2). Analogous reactions of CuI with [4,2′-pypzpym]I, [2,3′-pypzpym]I or [2,4′-pypzpym]I yield [Cu4I6(4,2′-pypzpym)2] (3), [CuI2(2,3′-pypzpym)] (4) and [CuI2(2,4′-pypzpym)] (5), respectively. Relative to that of CuI, complexes 1–5 exhibit enhanced catalytic activities towards the Chan–Lam cross-coupling reactions of imidazole and arylboronic acids in a H2OMeCN (v/v=2:1). This catalytic system is involved in the CN cross-coupling reaction and works for a variety of imidazole derivatives as well as arylboronic acids with different electronic properties.