Cyclic spermidines

The conditional association constant for [18]aneN4 ( cyclic spermine ) with ATP - at pH 7.5 is calculated from the (3L value (Table 5) and protonation constants (Table 1) to be 2.4x 105 M-1, which is larger than the association constants for the linear spermidine (9 xi 02 M ) and spermine (9.5 x 103 M-1)23). It is also of interest that cyclic spermine is selective for ATP over AMP (ratio association constants is 700), while linear spermine prefers ATP to AMP only by a ratio of 26 to 1 43). The selective complexation of biologically important anions is of particular interest, especially if the ligands are converted into selective anion carriers by attachment of lipophilic hydrocarbon chains. 

Verbascenine (205) has been isolated from the aerial parts of Verbascum species (140). Its structure elucidation was based on chemical degradation reactions as well as careful analysis of spectral data (140). In addition to spermidine, spermine was isolated from a KOH melt reaction and identified as its tetraacetyl derivative. The two cinnamic acid residues were identified by spectroscopic methods. A C=C double bond was found in only one of these units. The other cinnamic acid residue is part of a / -aminodihydrocin-namide. Therefore, verbascenine must be cyclic. The number of possible structures was reduced to two (205 and 206) on the basis of the formation of certain derivatives and their spectroscopic properties. Structure 205 is preferred for verbascenine because of the mass spectral behavior of its... 

Concerning the nature of the polyamine alkaloids, characteristic differences exist. In the case of putrescine alkaloids the base is always a chain in spermidine and spermine alkaloids the cyclic form is predominant. The 13-membered and 17-membered lactams are the preferred rings in the spermidine and spermine alkaloids, respectively. As shown in Scheme 41... 

The three catechol groups of enterobactin are carried on a cyclic serine triester structure. A variety of both cyclic and linear structures are found among other catechol siderophores. " For example, parabactin and agrobactin (Fig. 16-1) contain a backbone of spermidine (Chapter 24). After the Fe -enterobactin complex enters a bacterial cell the ester linkages of a siderophore are cleaved by an esterase. Because of the extremely high formation constant of M for... 

There are two catecholate siderophores which may be chosen as model compounds for synthesis the cyclic enterobactin and the linear parabactin precursor N. N8-bis(2,3-dihydroxybenzoyl)spermidine. Both of these natural products are capable of the rapid removal of iron from transferrin, the human iron transport protein 89-90). The synthesis of these and other catecholate ligands routinely requires protection of the phenolic oxygens (for example, by methyl, benzyl or acetyl groups). Very few preparations of catechol-containing siderophores have appeared in which the unprotected 2,3-dihydroxybenzoyl group is used in the synthesis 91,92). 

Fig. 7a. General syntheses of catechol siderophore analogs containing a linear cyclic amine backbone. The amine may vary in the chain length (for spermidine m = 3, n = 4, R[ = R2 = H) and in the substitutents of the terminal amines [E.g. alkylated according to Ref. 117 spermine m = 3, n = 4,...

In this chapter we describe cyclopeptide alkaloids, spermine and spermidine alkaloids, long-chain acid amides, and the cyclic oligopeptides isolated from higher plants since 1985. 

Figure 18 shows typical cyclic voltammetric i-E curves for 1.0 mM (A) cadaverine (CAD), (B) putrescine (PUT), (C) spermidine (SPMD), and (D) 0.8 mM spermine (SPM) in borax buffer pH 11 (BBpHll) at a microcrystalline diamond thin film deposited from a 0.5% CH4/H2 ratio and 10 ppm B2H6. Similarly shaped curves were observed for several other amines and polyamines (e.g., methylamine, ethylamine, propylamine, ethylenediamine, 1,3-diaminopropane, 1,6-hexamethylenediamine, and... 

Intramolecular amination with allylic acetates is used for the synthesis of cyclic alkaloids (Scheme This protocol can be applied to a synthesis of 21-membered cyclic amine skeleton of the spermidine alkaloid and l-azaspirocycles.f 3-Methylenepyrolidines are provided by the nucleophilic addition of allylzinc reagents to imines and subsequent Pd-catalyzed intramolecular allyIation.[" i... 

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