Synthesis typical reactant combinations

Typical reactant combinations for the synthesis of pyrimidines and pyrazoles... 

Multiple Parallel Synthesis (MPS) is typically carried out in a plate containing a matrix of 8 x 12 wells. It is typical for each well to contain a different combination of reactants (say an acid and an amine). Since the number of outcomes is then restricted (to say 96 amides) it could reasonably be argued that a full analysis of individual spectra need not take place in order to validate the plate for further work. Indeed, it may well be that the plate is destined for high throughput (biological activity) screening, and only hits from that process would then warrant a more rigorous approach. 

In a typical aluminosilicate zeolite synthesis, sodium aluminate is dissolved in water along with some fraction of the additional sodium hydroxide that is needed in the reactant mixture. Separately, sodium siHcate is mixed with the remainder of the sodium hydroxide. The two solutions are combined using the required mix order and agitation level, resulting in the initial zeolite gel. In some cases this initial gel is aged at an intermediate temperature for a time to allow evolution of... 

As far as the shape and size of the molecules are concerned, direct Mannich synthesis or typical reactions of Mannich bases, such as amino group replacement, open up the possibility of producing derivatives that have the chemical structures 1-VII (Fig. 182). Examples of such derivatives are compounds 494—503, all selected from products that have properties with useful practical applications. Thus, nonsymmetrical molecules with different A and B functionalities (type I in Fig. 182), along with symmetrically disubstituted molecules (type II), cyclic or branched compounds (types III and IV), as well as polymeric or crosslinked derivatives (types V-VII), can be produced as the result of appropriate combinations of mono- or polyfunctional A and B reactants. 

The first method uses the controlled concurrent hydrolysis of tetraethoxytitanium (IV) and tetraethoxysilane. This procedure has been labeled the mixed alkoxide method. Frequently, the acronyms TET (tetraethyltitanate) and TEOS (tetraethyl orthosilicate or tetraethoxysilane) are used for the respective reactants these are derived from the alternative names tetraethyl titanate and tetraethylorthosilicate. In examples described in patents, the synthesis involves adding TET to TEOS and then combining the alkoxide mixture with an aqueous solution of a SDA, which is typically tetrapropylammonium hydroxide (TPAOH). The resulting precursor mixture is then heated to a temperature of 175 °C to initiate crystallization. Subsequent washing of the crystallized solid with water, drying, and air calcination produces framework titanium-containing silicalite. 

Since Trost and co-workers demonstrated that the C-C bond forming reaction between an allylic acetate and a soft nucleophile such as sodio diethyl malonate was catalysed by Pd ° complexes [39], many attempts have been made to develop a catalytic asymmetric synthesis based on this principle. A particular problem is that the catalytic reaction involves nucleophilic attack on the allyl from the side remote from Pd so that the influence of the chiral ligand is severely curtailed. The most successful early work was the reaction type exemplified in Figure 4.18(a) described by Bosnich and co-workers [40]. The essential features are the combination of a CHIRAPHOS Pd catalyst with an allylic acetate reactant carrying aryl substituents at both terminal positions. This combination gave rise to products of allylic alkylation with a typical e.e. of 80%. 

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