Copper(II) acetate mediated conversion of ortho aminomethyl substituted isoquinolines to bis(isoquinolylcarbonyl)amides

Abstract

An ethanolic solution of ortho aminomethyl substituted isoquinolines, on stirring in air with half equivalent of [Cu(OAc)2(H2O)], afforded [Cu(1-L)(OAc)] (1) and [Cu(3-L)(OAc)] (2) {1-L=bis(1-isoquinolylcarbonyl)amide ion and 3-L=bis(3-isoquinolylcarbonyl)amide ion}. This reaction involves the oxidation of a methylene group and the formation of a bond between nitrogen and carbon in N–C(O) through coupling. The free ligands can be isolated as crystalline solids from compounds 1–2, by extrusion of the Cu2+ ion using EDTA2−. The molecular structure of 1·2.5H2O has been established and the copper(II) center has a pseudo square-planar N3O environment. A packing diagram shows the existence of a centrosymmetric dimer in which two copper centers are intermolecularly linked by the O2 atom of the amide function, leading to a Cu2O2 unit.