How to Plan a Synthesis Some Approaches and Examples

In planning a synthesis we often have to consider four interrelated aspects  

You have had some experience with certain aspects of synthetic strategies in earlier sections. 

Consider a problem in which we are asked to outline a synthesis of 2-bromobutane from compounds of two carbon atoms or fewer. This synthesis, as we shall see, involves construction of the carbon skeleton, functional group interconversion, and control of regiochemistry. 

We begin by thinking backward. The final target, 2-bromobutane, can be made in one step from 1-butene by addition of hydrogen bromide. The regiochemistry of this functional group interconversion must be Markovnikov addition  

Remember The open arrow is a symbol used to show a retrosynthetic process that relates the target molecule to its precursors  

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