It is an analytical technique used in which the deconstruction or fragmentation of targeted organic molecule is done to produce starting material, generally called as “synthon”.
Fragments generated via a particular pattern of break down. It is called as retro synthesis because it is a reversible process of chemical synthesis. E.J Corey gave this concept in his book The logic of chemical synthesis.
It involves some terminologies such as:
Disconnection which means the breakdown of bonds between atoms.
Reagents are those moieties utilized in chemical synthesis.
Synthon ion or radical formed after a disconnection.
FGI or FGE was written as a double arrow, Functional group interconnection, or equivalence.
Rules for retro synthesis:
- All the obtained fragment ions should be in their stable forms.
- After the deconstruction of a bond number of fragmented ions should be less as possible.
- Breakdown of bond always takes place through a carbon hetero atom and they accommodate their lone pair due to high electronegativity than carbon.
- It is not always possible to get stabilized ions after a disconnection; in that case, FGI (Functional group interconnection) can be used to get sufficiently stabilized ions.
- Fragmented ions can be positively or negatively charged and hence are replaced by required chemical moieties.
- The relationship between the present groups needs to be known. If a proper directing group is present then it should be disconnected in the last to get the target molecule.
- Firstly, the electron-withdrawing group should be disconnected.
- In some cases FGI is required then it must be done at the proper stage to have the desired orientation.
- The sequence that requires more steps or additional reactions must be avoided.
- If a compound contains two parts by heteroatom removal should be next to heteroatoms.
- To get a clear idea about the structure of naturally available compounds.
- It is a useful technique to prepare a compound to analyze the mechanism of the reaction and biological metabolism. One good example is the labeled compound.
- To prepare pharmaceutical compounds, dyes, polymers, etc. which are useful to mankind.
- Novel problems required modern solutions that lead to the development of modern chemistry.