Template-directed syntheses

Simidzu et al.70) carried out template-directed synthesis using various types of templates, e. g neutral ones, 34 (PSt TCT) and PSt TCTC, and cationic ones, such as APVP, 35 (APVP PSt), UPVP PSt, ARPVP, APEI, and 36 (ARPEI). They obtained a large amount of purine-containing oligomers (dimer or trimer) as compared to pyrimidine ones by condensation of nucleotide mixture in the presence of the neutral templates containing pyrimidine bases, such as PSt TCT and PSt TCTC. The authors stated from the results that the existence of the... 

The head-to-tail-coupling reactions described above are potentially useful in the design of dynamic combinatorial libraries. Features of these reactions include the rapid and reversible formation of carbon-carbon bonds, multifunctional ene-imine building blocks, and formation of stereo centers upon ene-imine linkage. Support for template-directed synthesis utilizing ene-imine building blocks is the formation of a poly ene-imine species that could recognize 3 -GGA-5 sequences of DNA.48 It is noteworthy that some polyene-imines are helical and could form a triple helix with DNA. 

An early review on the template-directed synthesis of oligonucleotides using imidazo-lides of nucleoside S -phosphate is included in reference 153]. 

Template-directed synthesis has been the object of much recent attention in the field of material science [169]. Using self-assembled aggregrates as a tern-... 

Zhan, Z.-Y. J. Lynn, D. G. Chemical amplification through template-directed synthesis. J. Am. Chem. Soc. 1997,119,12420-12421. 

Another recent concept is the template-directed synthesis from dynamic combinatorial libraries. Here, one or several building blocks that are prone... 

The synthetic strategy used for the construction of concave pyridine bislactams 3 (Scheme 1) can also be applied to other concave bases. When instead of a pyridine-2,6-dialdehyde 4, l,10-phenanthroline-2,9-dicarbaldehyde (9) was used in a metal ion template directed synthesis of macrocyclic diimines, after reduction, also macrocyclic 1,10-phenanthroline diamines 10 could be obtained in good yields. Here too, the crude diamines 10 were used in the next reaction step. Bridging of 10 with diacyl dichlorides 8 gave concave 1,10-phenanthroline bislactams 11. Scheme 2 summarizes the synthesis and lists the synthesized bimacrocycles 11 [18]. 

If during the template-directed synthesis of a rotaxane, the location of two identical recognition sites ( stations ) within its dumbbell component can be arranged (Fig. 13.3a and b), a degenerate, coconformational equilibrium state is obtained in which the macrocyclic component spontaneously shuttles back and forth between... 

As already said, catenanes are minimally composed of two interlocked rings. If it is arranged during the template-directed synthesis to have two identical units, that is, recognition sites, located within two different macrocycles, then the resulting... 

Figure 15. The template-directed synthesis of the [2]catenanes 32-4PF6-384PF6. The insets show (i) the intermediate [2]pseudorotaxane formed during the course of catenane formation and (ii) the solid-state structure of the [2]catenane 324+.

Figure 19. The template-directed synthesis of the [2]rotaxane 56-4PF6.

Hoffmann, M., Wilson, C. J., Odell, B., Anderson, H. L., Template-directed synthesis of a pi-conjugated porphyrin nanoring. 

Ashton, P. R., Matthews, 0. A., Menzer, S., et ai, Molecular meccano, 27 - A template-directed synthesis of a molecular trefoil knot. Liebigs Annalen-Recueil 1997, 2485-2494. 

Raymo, F.M., Stoddart, J.F. Organic Template Directed Synthesis of Catenanes, Rotaxanes and Knots. In ref. 4b, p.143. 

A rich variety of materials (including precursors) have been incorporated into the template-directed synthesis.33 169 170 Curable liquid prepolymers are particularly attractive because they have been widely used in replica molding with resolutions better than a few nanometers. By judicially selecting a monomer, the volume shrinkage involved in... 

Fig. 3 The template-directed synthesis ofthe[2]catenate[3-Cu]-BF4 and its reversible demetallation.

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