Recent Study on Synthesis and Characterization of Mannich Aminomethylation Products of Metal (Alaninato) Complexes Using 1-Nitropropane as the Carbon Acid

Synthesis of Mannich aminomethylation products starting from metal amino acid complexes have
gained much attention due to their applications as potent stimulators for the release of hormones, as
catalysts, as thermoelectric switches and in polymerization reactions. Mannich aminomethylation
products have been synthesized by one-pot template condensation reaction of bis(alaninato)metal (II)
complexes, M(aa)2, with formaldehyde and carbon acid 1-nitropropane. The DL-isomer and the Lisomer
of the metal(alaninato) complexes of Cu(II), Ni(II) and Zn(II) were used separately for the
synthesis of Mannich aminomethylation products in order to study the differential reactivities of the
stereoisomers of the complexes. Differential reactivities were observed for the isomers in the form of
different products isolated at the end of the reaction. Role of pH in Mannich aminomethylation reaction
was studied by carrying out the reactions under acidic (pH = 4-5) and basic (pH = 9) conditions. The
synthesized complexes were characterized by elemental analysis, ESI mass analysis, UV, IR, NMR
and ESR. With the Ni(II) complex, both the DL-isomer and the L-isomer were found to give the same
product. Hence, it is clear that the carbon acid 1-nitropropane is sufficiently acidic to involve in
Mannich aminomethylation reaction with all the three metal(alaninato) complexes of Cu, Ni and Zn.