Synthetic strategies divergent

On the other hand, branched building blocks [30] possess inherent branching points remote from the site of connection. These monomers can be simple or complex in design and have been used in both divergent and convergent synthetic strategies. In addition, branched monomers can also be used to install utilitarian functionality within cascade molecules. 

Figure 7. Divergent synthetic strategy to obtain polynuclear metal complexes of dendrimer shape. - ° Each deprotected compound of the dive ent synthetic approach can be used as a core in convergent synthetic processes. Some of these routes starting from a tetranuclear core are illustrated in Figure 8.

Pyridine-based ligands which have been used for dendrimers are 2,2-bipyridine (bpy) 17,2,3-bis(2-pyridyl)pyrazine (2,3-dpp) 18 and its monomethylated salt 19, and 2,2 6, 2"-terpyridine 20. Their transition metal complexes possessing dendritic structures were first reported in the collaborative work of Denti, Campagne, and Balzani whose divergent synthetic strategy has led to systems containing 22 ruthenium centers. - The core unit is [Ru(2,3-dpp)3] 21 which contains three... 

Astruc and co-workers were the first to report divergent a[ roaches to the construction of organometallic molecular trees. A representative example of their exciting synthetic strategy for the synthesis of multimetallic arborols is illustrated in Scheme 8. The growing step is based on the fact that the n-com-plexation of aromatic compounds by electron-withdrawing cationic organo-transi-... 

This section concludes with a description of tandem synthetic strategies (Section 14.1.6) in which sequential reactions involve combinations of steps such as dendrimer formations combined with cyclic peptides (Section 14.1.6.1), chemoselective cyclization combined with divergent syntheses (Section 14.1.6.3), and many thiol-based reactions and cyclizations (Sections 14.1.6.4—14.1.6.7) J18 ... 

However, the divergent synthetic strategy also permits covalent construction of a dendritic shell around a function-bearing core unit (Fig. 6.8 further examples are given in Section 4.1). 

SCHEME 16.1 Structures of multivalent architectures and their general synthetic strategies, (a) Convergent approach, (b) Divergent approach. 

Figure 4. Schematic of dendrimer synthetic strategies A. Divergent growth B. Convergent growth ...

FIGURE 15.3 Two most common synthetic strategies for dendrimers. (a) Divergent synthetic approach, (b) Convergent synthetic approach. 

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