Reactions of tris[(2S)-2-(aminomethyl)pyrrolidine]nickel(II) ion with alk-3-en-2-ones or 4-hydroxyalkan-2-ones: formation of an optically active tetra-aza macrocycle

Abstract

Reactions of [Ni(ampr)₃]²⁺[ampr =(2S)-2-(aminomethyl)pyrrolidine] and several alk-3-en-2-ones or 4-hydroxyalkan-2-ones were carried out, and the resulting nickel(II) complexes separated chromatographically. Structures of the complexes are proposed based on i.r., c.d., proton n.m.r., and elemental analytical data. The products with but-3-en-2-one were a tetra-aza macrocyclic complex and an open-chain complex, where reaction at the secondary amino-group of ampr is selective. The products with 4-hydroxybutan-2-one were the same open-chain complex as above and another open-chain complex. The reactions with 4-methylpent-3-en-2-one and pent-3-en-2-one occurred specifically at the primary amino-group, due to steric repulsions involving the methyl group(s) on the β-carbon, and resulted in open-chain complexes.