Copper assisted acetylation of 3-amino-5-methylpyrazole: first copper complex of an aminopyrazole

The copper(II) complex [(3-AMP)(3-Ac-AMP)Cu](ClO4)2 (3) was obtained by the reaction of 3-amino-5-methylpyrazole (3-AMP, 1) with Cu(ClO4)2 in acetonitrile. The reaction involves the amidation of acetonitrile under mild conditions and thus provides a new entry into amidation chemistry. Furthermore, complex [(3-Ac-AMP)Cu](ClO4)2 (4) was obtained from the reaction of 3-acetamido-5-methylpyrazole (3-Ac-AMP, 2) with Cu(ClO4)2. Both complexes were analyzed by single crystal X-ray crystallography, which establishes the nature of the complexes. The Cu in complex 3 is in a distorted trigonal bipyramidal environment, whereas the metal in complex 4 is in a square-planar environment.