It is an analytical technique in which the decomposition or fragmentation of a targeted organic molecule is used to produce the starting material, commonly referred to as a “synthon”.
fragments produced through a particular pattern of breakage. It is called retrosynthesis because it is a reversible process of chemical synthesis. EJ Corey gives this concept in his book Logic of chemical synthesis.
It includes some terminology such as:
Disconnection means breaking of bonds between atoms.
Reagents are the ingredients used in chemical synthesis.
The synthon ion or radical is formed after a dissociation.
FGI or FGE was written as double arrow, functional group interconnection or equivalence.
Rules of retro synthesis:
- All the received fragment ions should be in their stable forms.
- The number of fragmented ions after the dissociation of a bond should be as low as possible.
- The breaking of the bond always occurs through a carbon hetero atom and due to the higher electronegativity than carbon they accommodate their lone pair.
- It is not always possible to obtain permanent ions after dissociation; In that case, FGI (Functional Group Interconnection) can be used to obtain a sufficiently stable ion.
- Fragmented ions can be positively or negatively charged and are therefore replaced by the required chemical fragments.
- The relationship between existing groups needs to be known. If a proper directing group is present it must be truncated at the end to obtain the target molecule.
- First, the electron-withdrawing group must be truncated.
- In some cases FGI is required then it should be done in proper stage for desired orientation.
- Orders that require more steps or additional reactions should be avoided.
- If a compound consists of two parts then the heteroatom must be next to the heteroatom to be removed.
- To get a clear idea about the structure of naturally available compounds.
- It is a useful technique for preparing a compound to analyze the mechanism of reaction and biological metabolism. A good example is labeled compound.
- Preparation of medicinal compounds, dyes, polymers etc. useful to mankind.
- Novel problems required modern solutions that would lead to the development of modern chemistry.