Divergent approach

The entire domain of "new-lead" discovery has expanded considerably. This development has affected what have traditionally been divergent approaches, namely QSAR and stmcture-based design, leading them to become integrated so as to provide a more powerful approach (135). Several recently pubHshed comprehensive volumes capture the state of the art and can be consulted to determine precedents relevant to any particular study (134-137). 

Divergent Approaches to Phosphorus-Containing Dendrimers and their Functionalization J.-P. Majoral, A.-M. Caminade... 

Divergent Approaches to Phosphorus-Containing Dendrimers and their Functionalization... 

In a recent report [171] Newkome and He extended this concept and described the use of two ruthenium centers per appendage [—(Ru)—(x)—(Ru)—] towards construction of a four-directional dendrimer (e.g., 81, Fig. 36). A combination of convergent and divergent approaches, hence, allowed the stepwise construction of metallodendrimers via controlled metal complexation. 

Constable has described [172] the construction of a variety of metallodendrimers using both convergent and divergent approaches wherein the metal... 

PAMAM dendrimers are synthesized by the divergent approach. This methodology involves the in situ branch cell construction in stepwise, iterative stages (i.e. generation = 1, 2, 3. ..) around a desired core to produce mathemat-... 

In another study, nucleic acid dendrimers were synthesized via both convergent and divergent approaches, and their purity assessed using PAGE [23, 24], In Figure 10.6 is shown convergent synthetic route, which involves ... 

High yields and selectivities are required, especially when the divergent approach is used. Average selectivities of > 99% per conversion are needed. 

Laboratory procedures are presented for two divergent approaches to covalent structure controlled dendrimer clusters or more specifically - core-shell tecto(dendrimers). The first method, namely (1) the self assembly/covalent bond formation method produces structure controlled saturated shell products (see Scheme 1). The second route, referred to as (2) direct covalent bond formation method , yields partial filled shell structures, as illustrated in Scheme 2. In each case, relatively monodispersed products are obtained. The first method yields precise shell saturated structures [31, 32] whereas the second method gives semi-controlled partially shell filled products [30, 33],... 

Like the divergent approach, the convergent method also involves repetition of several basic chemical reactions. However, the reaction cycles are used to synthesize individual dendrons (dendrimer branches) instead of complete dendrimers. The dendrons have a protected focal point which can be activated in the last synthetic step and linked to two or more attachment points of a core molecule. Dendrimers synthesized by either method contain defects, but the problem is less pronounced for materials prepared by the convergent method. 

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