Reactions of copper(II) complexes of optically active N-substituted diamines with alk-3-en-2-ones or 4-hydroxyalkan-2-ones: formation of optically active macrocycles
Abstract
The reaction of bis[(3S)-3-aminopiperidine]copper(II) with but-3-en-2-one in methanol in the presence of ammonia gives an optically active tetra-azamacrocyclic complex in ca. 80% yield. Analogous optically active complexes are also obtained from bis[(3S)-3-aminohexahydroazepine]copper(II) or bis[(2S)-2-(aminomethyl)pyrrolidine]copper(II) by the same procedure. The introduction of methyl and/or a hydroxyl group at the C4 position of but-3-en-2-one leads to a decrease in the reactivity of the ketones, and changes the species and distribution of the reaction products. In particular, when the C4 position is fully substituted with methyl groups, C–N bond formation with the secondary amino group no longer proceeds. The change in the reaction mode due to the substituents at C4 is discussed.