Synthesis as a Search Goal Ambiguous but Unquestionable

If our task were to synthesize a bright red azo dye with the properties of a base, theory would bring us to structure 38, but would say nothing about the nature of the alkyl groups. The investigator must make a selection from a 

Besides the required pattern of activity, there are many other critically important characteristics of a potential drug such as its toxicity, possible short-and long-term side effects, its ability to accumulate in or to be excreted from an organism, its stability for storing and sterilization purposes, its compatibility with other medicines, etc. Therefore, the discovery of promising biological 

A burst of synthetic activity in this area ensued. By 1947, over 5000 sulfanilamides were synthesized and tested as medicinal drugs against a number of diseases. As a result of this wide screening, more than 100 candidates possessing the desired biological activity were selected. Less than a dozen from this list turned out to have the set of additional properties required for the drug. They were widely used over the next several decades. Some, for example the sulfa drugs 39-42, are still used today. 

When it is possible to identify a definite structural feature responsible for biological activity e.g. the sulfanilamide moiety in 39-42), the search for an efficient drug is expedited. Usually, however, the situation is far from being that simple. Structure-activity correlations are not that easy to establish. As an example, let us briefly consider the typical patterns of biological activity in steroids. 

For at least two decades, steroids remained as one of the most challenging synthetic targets. The intense pursuit of these studies made available a wide array of hormonal drugs. At the same time, considerable progress was gained in the elucidation of the intricate mechanism of steroidal hormonal action. One of the more spectacular results of this study was the elaboration of an approach to family planning. The creation of oral contraceptives, ( the Pill 50, currently used by at least 50 million women worldwide) resulted in tremendous social consequences worldwide. 

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