Role of the nature of the metal centre in the catalysed addition of β-dicarbonyls to electrophilically activated nitriles

Abstract

The reaction of methyl acetoacetate with trichloroacetonitrile to give 2-amino-1,1,1-trichloro-3-methoxycarbonyl-4-oxo-2-pentene is catalysed, at room temperature, by acetylacetonate complexes [M(acac)_n](n= 2 or 3). The catalytic efficiency of the metal centres follows the order Zn^II≃ Co^II > Mn^II > Mn^III > Ni^II > Cu^II > Fe^II≃ Fe^III, which can be related (with the exception of Fe^II) to the degree of ionic character of the M–O bond, in the metallo-organic ring. The metals Al^III, Cr^III, and Pd^II are catalytically inactive because of their inertia towards ligand exchange.