Catechoylamides

Raymond s group has studied the complexation of Pu+1 by linear and cyclic catechoylamide ligands in which the plutonium has CN = 8 through interaction with phenolate groups (Figure 6). 

The structures of several [M(catechol)3] complexes are known, including [Fe(cat)3], and all have been found to be pseudo-octahedral. There exists oifly one crystal structure of an iron(ni) tris(catechoylamide), namely of a synthetic compound trivially named bicappedTRENCAM (Figure 7). The... 

In 1975 two catechol-containing linear siderophores, from Paracoccus denitrijicans, were reported1111 N1,N8-bis(2,3-dihydroxybenzoyl)spermidine and parabactin A. The former catechoylamide is a precursor of parabactin (Fig. 2), whereas the latter is a decomposition product of the same compound, generated by cleavage of the oxazoline ring into the threonyl moiety under acidic conditions. 

Table VI. Comparison of the amide I stretching frequencies for catechoylamide and salicylamide complexes. Spectra were taken in KBr...

The cyclic catechoylamides, in which R = (CH2)P are abbreviated as n, m, p, m-CYCAM. The sulfonated and the analogous nitro derivatives are indicated by n, m, p, m-CYCAMS and n, m, p, m-CYCAM-N02 respectively. The linear sulfonated catechoylamides are abbreviated as m, n, m-LICAMS. A prefix is added to indicate terminal N substituents... 

Table 6. Summary of actinide sequestering properties of tetrameric catechoylamides...

This dramatic difference between the monomeric catechols and the synthetic tetracatechol compounds confirm our original design concept that a macrochelate would be most effective biologically in Pu removal. Of the sulfonated catechoylamides only the... 

Table VII. Effect of Tetrameric Catechoylamides on the Distribution of 238Pu(IV) in Micea...

Table IX. Summary of Actinide Sequestering Properties of Tetra-meric Catechoylamides...

The most promising actinide squestering agents yet prepared (Table IX) are the sulfonated catechoylamide derivatives of linear tetra-amines. These compounds appear to strongly bind tetravalent actinides, while only weak complexation has been observed for trivalent and divalent metals. A derivative of the natural product spermine, 3,4,3-LICAMS, is more effective in plutonium removal at low dosages than any other sequestering agent tested to date. 

As a rule, the macrobicyclic catechoylamide compounds have been obtained by high-dilution techniques [135-138, 140]. However, the yield of these products is low. In particular, methyl-protected bicapped L1018 can be prepared via two high-dilution routes ( heme 4-16) in 3.5% and 27% yields. The product HeLlOlO is obtained by treatment of L1018 with boron tribromide in CH2CI2 [140]. 

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