Effect of different α-substituents on the Mannich reaction of copper(II) chelated α-amino acids with formaldehyde and acetamide: X-ray structure of aquabis(3-methylacetamido-5-methyl-oxazolidine-4-carboxylato)-copper(II)

Abstract

The reactions of a series of bis(α-substituted glycinato)copper(II) complexes, Cu(aa) 2, with formaldehyde and acetamide have been carried out. For Cu(aa) 2 with an activating α-alkyl or reactive α-hydroxyalkyl substituent, they undergo both aldol-type condensation and Mannich aminomethylation to yield complexes with an oxazolidine-ring and one methylacetamido pendant. The crystal structure of one of these complexes is reported. The Cu(aa) 2 with a non-activating α-alkyl substituent is diacetamidomethylated. A proposed mechanism to account for the above differences and an analysis of thermal decomposition data of the two types of complexes are further described.