Facile and Versatile Synthesis of Polydentate Metal Chelators with Both Amide and Oxime Donor Groups

Abstract

The first compounds with mixtures of deprotonateable amide and oxime donor groups that may act as tetradentate metal chelators were synthesized using the reagent N,N,N-triethyl-N-(propan-2-onyl oxime)ammonium chloride to add the oxime-containing arms to various amines with attached amides. This reagent avoids the complications due to competition between deprotonation of the oxime moiety and acid/base chemistry of the alkylation reaction. These compounds are based on either the simple "tripodal amine" framework, or on chiral, natural amino acid derivatives. The steric properties may be easily tuned by variation of the "R-groups" on the arms containing the functional groups.

Tris(1-propan-2-onyl oxime)amine

“…The molecular structure of (I) is similar to that observed for [N-(1-propan-2-onyl oxime)]bis[N-2-(N H ,N HH -trimethylacetyl)aminoethyl]amine (Goldcamp, Rosa et al, 2000) in that both have an open extended geometry rather than a folded geometry, as exhibited by tris[2-(benzoylamino)ethyl]amine . Viewing (I) along its threefold axis, one observes a rather shallow symmetrical cavity with a depth of 1.8 A Ê (distance from N1 to the centroid of the methyl C atoms) and a width of 4.1 A Ê (distance between methyl C atoms).…”

“…Compounds with several different functional groups are of interest as chelating ligands for transition metals. For the past couple of years, our research effort has focused on the reactivity of Ni, Cu and Zn complexes (Goldcamp, Robison, Krause Bauer & Baldwin, 2002;Goldcamp, Robison, Squires et al, 2002) of ligands sporting the tripodal geometry and incorporating oximate and mixed oxime/amide functionality Goldcamp, Rosa et al, 2000). Tris(1-propan-2-onyl oxime)amine, (I), otherwise known as tris(2-hydroxyiminopropyl)amine, Ox 3 H 3 , is such a ligand.…”

Tris[2-(benzoylamino)ethyl]amine

“…In contrast, an extended structure is observed for [N-(1propan-2-one oxime)]bis[N-2-(N H ,N HH -trimethylacetyl)aminoethyl]amine, (IV) (Goldcamp et al, 2000), and tris[N-(S)-(À)-()-methylbenzylcarbamoylmethyl]amine, (IV) (Hammes et al, 1998), which is attributed to the lack of intramolecular hydrogen bonding. This extended structure allows for easy access for metal and solvent interactions.…”

Oximinoalkylamines as ligands for Cu-assisted azide–acetylene cycloaddition

“…Widely applied oxime ligands such as dimethylglyoxime (DMG) and pyridine-2-carbaldoxime (PAO) ( Table 1, entries 3 -4), as well as known mono-, bis-, tris-, tetra-and hexa(oxyminoalkyl)amines 10 (Table 1, entries 5-15) which were readily available by oximinoalkylation of primary and secondary amines and ammonia were selected. For a more comprehensive study of the oxime-group effect "mixed" tripodal ligands (tris(iminomethyl)amines) bearing one or two oximinoalkyl groups in combination with pyridinylmethyl, benzimidazolylmethyl or triazolylmethyl donor "arms" (Table 1, entries 16-20) were also synthesized.…”