Syntheses of novel acyclic amino-amido ligands

Master Thesis


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University of Cape Town

Towards the labelling of biological macromolecules in contrast media, a synthesis of the novel bifunctional amido-ligands N,N' -bis[2-(N'',N''-dimethylamino)ethyl]-4-aminobenzylmalondiamide (67) and the 3-aminopropyl derivative (66) from appropriately C-functionalized malonates by amidation with N,N-dimethylethylenediamine (62) followed by reduction of the respective nitro (64) and cyano (63) groups is described. The synthesis of N,N'-bis[2-(N'',N''-dimethylamino)ethyl]iminodiacetamide (73) from diethyl N-benzyliminodiacetate (79) by amidation· with (62) followed by debenzylation is described. Herein is also reported the unsuccessful attempts to prepare a functionalized pentaamine ligand similar to (73) via the intermediacy of N,N'-bis[2-(N'',N''-dimethylamino)ethyl]-N'''-(2,2-diethoxyethyl) iminodiacetamide (112) whose preparation is also detailed. Attempts to this end via the Mitsunobu and Steglich coupling of N,N' -bis[2-(N'',N''- dimethylamino)ethyl]-N'''-(2-hydroxyethyl)iminodiacetamide (100) with N-tertbutyloxycarbonylglycine (105) also met with failure .. Further failed attempts to secure suitably functionalized intermediates by N-alkylation of diethyl iininodiacetate (70) with appropriate electrophiles are described. The successful functionalization of the pentaamine series of ligands by N-alkylation of (73) withpnitrobenzoyl chloride (118) to give N,N' -bis[2-(N'',N''- dimethylamino)ethyl] N''' -(4-nitrobenzamido)iminodiacetamide (119) is presented. The preparation of the non-functionalized novel trioxo heptaamine ligand N,N' ,N''-tris[2-(N'',N''-dimethylamino)ethyl]nitrilotriacetamide hydrochloride (86a) is also described. An investigative study towards the assembly of a novel triamine system for encapsulating NMR or isotopic NMR-active metal ions for possible use in diagnostic medicine is reported. The key facet to this end is the reported preparation of N,N' ,N''-tris(2-aminoethyl)propane-1,2,3-tricarboxamide (89) by controlled amidation of trimethyl propane 1,2,3-tricarboxylate (88) with ethylenediamine. The syntheses of functionalized and non-functionalized novel tetraamine dioxo and trioxo ligands from glycine, ethyl N-benzylglycinate (78), L-valine, and L-lysine via classical peptide synthesis methodology (in part) are described.

Bibliography: page 154.