Template polyamines

The subject matter of this chapter will be subdivided into sections concerning template synthesis of the complexes structural and thermodynamic properties of the complexes with synthetic cyclic polyamines complexes with mixed-donor macrocycles reactivity of the complexes cryptates and complexes with phthalocyanines and porphyrins. 

Another series of macrocydic complexes has been prepared by Busch and co-workers by the condensation reaction of either pyridine-2,6-dicarboxaldehyde or 2,6-diacetylpyridine with various polyamines (Scheme 38). 24,2628,2640 2645 Other examples of template reactions leading to different types of macrocydic complexes are reported in Schemes 39-44.2628 2646 2650 The selfcondensation of l-amino-2-carboxaldehyde in the presence of nickel(II) gives two types of macrocycle (Scheme 45), M51... 

Drandarov, K. Hesse, M. Lithium and proton templated (U-polyazamacrolactamization, new general routes to macrocydic polyamines. Tetrahedron Lett. 2002, 43, 7213—7216. 

Template effects play an important role in most of the cyclizations leading to alloxygen macrocycles. Usually, alkali or alkaline earth metal cations serve as a template ion. Transition metal cations are useful in the syntheses of macrocyclic polyamines. The template effect is less pronounced in the case when formation of mixed nitrogen/ oxygen macrocycles are formed in comparison with their all-oxygen analogues. 

The in situ synthesis of macrocyclic ligands by condensation of 2,6-diacetylpyridine with polyamines in the presence of metal ions represents one of the early demonstrations of the template effect . Curry and Busch reported the first penta-and hexadentate macrocycles (79 and 80)47), both of which are cyclized in the presence of iron(II) chloride tetrahydrate. The two ligands were isolated as highly... 

However, transition metals can also act as templates to make shapes in three dimensions. In 1977, Alan Sargeson reported the astonishing one-pot synthesis of a cage-shaped polyamine, templated by Coin, which offered an octahedral pattern [16]. Mechanistic details of the synthesis, taking place in water, in open air, at room temperature, are illustrated in Fig. 8. 

A chain-shape polyamine and ethylene glycol system favors the formation of layered aluminophosphates with an Al/P ratio of 3/4. For instance, ethylenediamine, diethylenetriamine, and triethylenetetramine combining with ethylene glycol solvent lead to the formation of layered aluminophosphates with an AFP ratio of 3/4 (see Table 3.9). Therefore, it is expected that using tetraethylenepentamine as template and ethylene glycol as solvent will result in the crystallization of a layered aluminophosphate with an AFP ratio of 3/4. Guided by this prediction, we did... 

Curtis and others showed that cyclic condensation also was possible in the absence of a metal template ion, but acid was necessary for those reactions. Possibly, the protonated amines formed an internal hydrogen-bonding network that acted as a template. Cyclization was observed in yields of up to 80% (Curtis and Hay, 1966 Kolinski and Korybut-Daszkiewicz, 1969 Tait and Busch, 1978a, 1978b). The isomers of the formed cyclic Schiff bases were difficult to separate. Reduction of the unsaturated macrocycles gave cyclic polyamines with up to six chiral centers and up to 20 diastereomeric isomers (Hay and Piplani, 1977 Kolinski and Korybut-Daszkiewicz, 1969). 

The resin-bound polyamine was used as a template for the solid-phase synthesis of a range of heterocyclic compounds, such as cyclic ureas 25 and cyclic thioureas 26. This work exemplifies our ongoing efforts on the solid-phase assembly of individual acyclic and heterocyclic compounds and combinatorial libraries using short peptides as starting materials. 

---