Commercially attractive targets

It is mandatory to ensure that the therapeutic target is appropriate and commercially attractive, and to define the required product performance... 

The relative simplicity of the structure of estranes compared with those of other classes of steroids has made this structural class an attractive target for work aimed at total synthesis from so-called coal tar starting materials. About half a dozen syntheses have been developed, one of which, the Smith-Torgov synthesis, is probably stiU used commercially. 

A target that has interesting or commercially attractive properties may exhibit deleterious side effects, or be unstable to storage and handling. Subsequent studies often show that structural modification to the basic skeleton gives a molecule with different characteristics and the new molecule becomes the synthetic target. 

In comparison to other biomacromolecules, enzymes have been the most attractive targets for DCC protocols. Biocatalysts are preferred for several reasons, (i) They are obviously integral parts of important biochemical pathways that may be of pharmacological relevance, (ii) They are often soluble entities that can be expressed in larger amounts, some of which commercially available, (iii) They offer very attractive features from an analytical point of view and inhibition can be easily... 

The use of AAAs as feed supplements appears an attractive approach either in itself or in combination with pro-, pre- and synbiotics, but the lack of animal feeding studies in which the efficacy of this approach could be determined makes it difficult to assess to what extent a two-barrier (targeting control at both the stomach and intestinal level) approach is commercially feasible. Also, since the viability of probiotics may also be affected by the use of AAA to increase the disinfection activity of the stomach, probiotics may need to be formulated in a way that protects them during stomach transfer. However, its potential should be determined in future research. 

As the range of components available for use in the azoic dyeing process expanded, research was simultaneously targeted on improvements designed to make the process more attractive to the commercial dyer. The necessity for the dyer to diazotise the Fast Base was removed with the introduction of stabilised diazonium salts [111], known as Fast Salts. Stabilisation was achieved by a judicious selection of the counter-ion to the diazonium cation various anions have found use in commercial Fast Salts and some examples are listed in Table 4-4. Particularly effective is the diazonium tetrachlorozincate, which can be readily prepared by adding an excess of zinc chloride solution to a solution of the diazonium salt. The precipitated complex diazonium salt is usually admixed with an inert diluent, which enhances its stability, and in use the dyer only needs to dissolve the powder in water to prepare the necessary diazonium salt solution. 

Schering chemists demonstrated that the target molecules 32 and 33 can also be synthesized in a one-pot reaction with enantioselectivity up to 84% ee when using 10-200 mol% proline as catalyst [65, 66], Because of easy access to the steroid precursors 28 and 29 from readily available raw materials, and the use of the economically attractive catalyst L-proline, this intramolecular aldol reaction has attracted commercial attention. At Schering L-proline catalysis has been conducted on a multi-kilogram scale [67]. 

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