Diamines macrocyclic

Table 1 Equilibrium constants log K for the protonation of macrocyclic diamines [4] in water and methanol at 25°C.

Two kinds of ligands of type H have been synthetized. A ligand 46 formed by oxidative coupling of two molecules of a cyclopentapeptide via an S—S bridge derived from two cysteine moieties has been reported (92, 93). On the other hand, monoprotected macrocyclic diamines (51 and HN(CH2CH2OCH2CH2)2NH) have been condensed with acid... 

The highest flexibility for a variation of the functional group and the chains X and Y (i.e. the size of the rim of the lamp shade) will be realiad when the synthesis of 3 is convergent and modular (Scheme 1). Amide bonds can easily be formed in macrocyclizations [13], therefore macrocyclic diamines 7 and diacyl dichlorides 8 had to be prepared. For the synthesis of macrocyclic diamines 7, also a large number of reactions are known. However, in this case a reduction of a macrocyclic diamide could not be achieved [11]. Therefore, another route was used the formation of macrocyclic diimines 6 (bis-Schiff bases) followed by NaBH4 reduction to the macrocyclic diamines 7. This approach has the advantage that for the construction of macrocyclic diimines 6, the metal ion template effect [14] may be exploited. 

A large number of concave pyridines 3 have been synthesized starting from pyridine-2,6-dicarbaldehydes 4, heteroatom containing a,o>-diamines 5 and diacyl dichlorides 8 (Scheme 1). In the first macrocyclization, the dialdehyde 4 and the diamine 5 were condensed in the presence of an alkaline earth metal ion to give a complex of a macrocyclic diimine 6 which was then reduced to the macrocyclic diamine 7. The yields of this reaction are excellent ( > 90%) when the size of the metal ion is adjusted to the size of the macrocycle formed. Mg was used for the formation of 15-membered, Ca for 18-membered and Sr for 21-membered rings. The macrocyclic diamines 7 were oils which could be purified in some cases. However, for the synthesis of the concave pyridines 3 the purity of the crude diamines 7 was sufficient. 

In the synthesis of all concave acids and bases, a difunctionalized molecule A-A was cyclized with a difunctionalized bridge component B-B. Because telo- and polymerizations are the main side reactions [29] the isolated macrocycles need not be the expected [1 -I- 1] addition products, the (-A-AB-B-)i cycles, [n - - n] Telomers with the general structure (-A-AB-B-) are also possible. These molecules have identical elemental analyses and similar IR and NMR data. Therefore the mass spectral analyses of the macrocycles are very important because this is the only method which can tell [1 -t- 1] and [2 -t- 2] addition products apart. Due to the high molecular weight of the concave acids and bases, special MS techniques were necessary in some cases [30]. In the case of the macrocyclic diamine 7 [R = NEt2, X = CH2(CH20CH2)2CH2], a [2 -t- 2] addition product could be isolated and characterized besides the desired [1 + 1] product [12a]. 

Macrocyclic diamine 14 and triglycolic acid dichloride 15 were condensed under high-dilution conditions to form 16 in 45 % yield. Subsequent reduction of 16 using diborane yielded the [2.2.2]cryptand as the bis-borane adduct. Acidic work-up with 6 N hydrochloric acid afforded 7 in 90% yield. 

The principle of the high-dilution (h.d.) method consists in the condensation of macrocyclic diamines with highly reactive acid dichlorides or, alternatively, 2,4-dinitrophenyl diesters in an inert solvent like toluene 22). The yields of the resulting diamides are usually good, although [1.1. ljcryptand was obtained in this manner only in 10% yield, accompanied by a dimer (30% yield)23. ... 

New polyamine macrocycles were prepared by an in situ reduction of thiophen-2,5-dicarbaldehyde and a 1,n-alkanediamine using a mixture of sodium borohydride and borax.10 Thirty-two- and thirty-eight-membered macrocyclic diamines containing two di(trimethylene) triamine groups have been synthesized and shown to act as ditopic... 

Macrocyclic diamine alkaloids from marine sponges... 

But in most macrocyclizations, thermodynamic control is not yet possible. These macrocyclizations have therefore been carried out under kinetic control, often using high dilution conditions. Typical reactions are the formation of lactams, for instance, in the second macro-cyclization during the synthesis of concave pyridines 1 by reaction of the macrocyclic diamines 8 with diacid dichIorides. or the reaction of calix[6]arene with... 

Ji5)-PhCHMeNH3 CIO4 in favour of the 5-isomer. Chiral macrocyclic diamines... 

Chitosan has been modified with different mono as well as disaccharides. (Yang et al., 2003) have also reported the metal uptake abilities of macrocyclic diamine derivative of chitosan. The pol5mier has high metal uptake abilities, and the selectivity property for the metal ions was improved by the incorporation of aza crown ether groups in the chitosan. Me Kay et al. (1989) used chitosan for the removal of Cu, Hg +, Ni ", and Zn within the temperature range of 25-60°c at neutral pH. Further adsorption parameters for the removal of these metal ions were reported by Yang etal. (1984). 

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