Synthesis as an Instrument of Exploration

The goals discussed above refer to the preparative function of synthesis to supply essential materials. The actual route used to acquire the product is immaterial the final results are the same whether or not target compounds are isolated from natural sources or obtained through biochemical processes. (In the majority of cases, though, a chemical synthesis turns out to be a more common and reliable approach.) 

There is, however, an area where synthesis does more than fulfill an auxiliary role. It represents the essence of the task. The most obvious examples are related to the problems of structural proof for novel compounds obtained as the result of previously unknown reactions or those isolated from natural sources. In such cases, final and unambiguous proof of the structure (as deduced from analytical data) is achieved by an independent synthesis of the same compound followed by direct comparison with an authentic sample. This claim might now appear obsolete. In fact, it may seem that modem powerful physical methods for structural analyses, such as nuclear magnetic resonance spectroscopy, high- 

An independent synthesis is devoid of these shortcomings. The structure confirmed by this route can be considered to be an absolute truth no less than if established by a trustworthy Supreme Court. 

In many cases an independent synthesis turns out to be the only practical method to choose correctly between several tentative structures of an unknown compound. For cases in which the studied compound is available in a very small amount (less than a milligram or even a microgram), degradation methods are not feasible. Even instrumental methods in such cases may prove to be inconclusive in structural analysis. The exact structure of such natural products as the previously mentioned JH 8 or bombicol 12 were conclusively elucidated only after their total synthesis. Some more recent examples follow. 

Along with its role as a tool for structure elucidation, synthesis fulfills a different, less obvious, and perhaps more important function. The studies aimed at a total synthesis represent one of the most powerful routes to delve into the chemistry of the target compounds. An understanding of the chemical peculiarities of an organic compound is a necessary condition for the success of its synthesis. Yet the factual data necessary for such an understanding are most effectively accumulated in the process of synthesizing the targeted compound. Why  

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