Methodologies of Organic Synthesis

Organic synthesis is a useful method for the preparation of fine chemicals of profound importance. Multi-step synthetic schemes are usually designed for synthesizing a target molecule, involving various strategies. The importance of organic synthesis can be judged by the fact that it is an alternative way of producing medicinally important natural products, which are often biosynthesized in low yields.

Organic synthesis of molecules may be achieved by employing various methodologies, which are discussed below:

1. Linear Synthesis
   As the name suggests, this method involves the synthesis of a large molecule, starting with a smaller molecule in a linear fashion. The target is synthesized by building upon the starting material using various reagents, catalysts, and reaction conditions, all in a linear pathway. So if we want to synthesize compound “A”, a linear synthetic strategy would look like:
   
   An example is the linear synthesis of gemcitabine by Linclau et. al. in 2015.
   
2. Convergent Synthesis
   This strategy involves the synthesis of various fragments of a target molecule, which are combined in the last step (converged) to achieve the target.

Convergent synthetic strategy is very useful for achieving the synthesis of the target molecule in high yields. In contrast to linear synthesis, where the yield lowers at each successive step, the overall yield in convergent synthesis is pretty handsome.

An example is the aminmethylene peptidomimetics synthesis by Yudin et. al. in 2012.

1. Divergent Synthesis
   Divergent synthesis is an effective methodology for synthesizing a library of compounds. This is done by synthesizing variety of analogues of a molecules by functional group inter-conversion, addition or removal of a functional group, rearrangement, etc., in a divergent manner.
   Divergent Synthesis of Fawcettimine-Type Lycopodium Alkaloids is an example of this methodology.
   

    

   
   
   
   
   
   
   Photo credits: wallpapercave.com
   Reference links: http://www.sciencedirect.com/science/article/pii/S0008621515000129
   http://www.nature.com/nprot/journal/v7/n7/full/nprot.2012.066.html
   http://onlinelibrary.wiley.com/doi/10.1002/chem.201403163/abstract