What kind of consideration is necessary before starting a synthesis

2 What kind of consideration is necessary before starting a synthesis  

one must choose the starting material(s). All the synthesis starts from readily available commercial products. It is therefore important for a chemist to look at catalogs of big reagent manufactures like Aldrich. By reading catalogs we can have knowledge on the prices of many possible starting materials. It is also important to be familiar with the industrial intermediates in the chemical and pharmaceutical industries. We may be able to obtain such intermediates by the courtesy of people in these industries. 

it is the time to make a gross plan of the synthesis. One must decide the key reaction to be employed. In the case of an enantioselective synthesis, the timing of introducing the required asymmetry correctly is always of great importance. Of course, one must think about each of the steps, and the order must be fixed by which each step is to be executed. There are many possible synthetic routes for a biofunctional molecule. At the beginning it is not so easy to devise the best route. Through experimentation 

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