in this seminar i have discussed about Retrosynthesis guidelines for C-X Disconnection in advance organic chemistry

1. Retrosynthesis guidelines for C-X
Disconnection
SHIVAM
M.PHARM (IS T
SEM)
SPER, JAMIA HAMDARD

2. Disconnection approach
Imaginary approach for organic synthesis which involve imaginary
breakdown of target molecule into available starting material by
imaginary breakdown [disconnection] or FGI called disconnection
approach.
The construction of synthetic pathway by working from Target
molecule (TM) called retrosynthesis analysis.
FGI : When real and workable reagents are not obtained than we
convert one functional groupto another functional group.

4. How to choose disconnection:
Find out functional group in TM (ester, amide, amine, thioether,
ether, etc)
When two part joined by heteroatom, disconnect next to hetroatom.
Disconnect reactive group first to form known reactant.
If TM is mor reactive than synthetic equivalent or reactant than
disconnection is not favourable.

5. Guideline 1 :
Consider the effect of each functional group on the others. Add one that will inc.
reactivity in a helpful way

6. Guideline 2 :
Changing one functional group to another may alter reactivity dramatically

7. Guideline 3 :
Some substituent are difficult to add so it is best to start with them already
present.

9. Guideline 4 :
If a series of reaction must be carried out, start with one that gives a single
product unambiguously and not one that would a give a mixture

10. Carbonyl derivative RCOX
Point of disconnection is bond between hetroatom and carbonyl
group

11. Acid chlorides are regularly used in these syntheses as they are the most
electrophilic of all acid derivatives and as they can be synthesized from the acids
themselves

12. Ether ROR’
The disconnection approach for the synthesis of ethers also targets the
bond between CO. There is a possibility of bond cleavage from either
side of ‘O’ as there are two ‘C-O’ bonds present in the ethers.

13. Another Eg:
Nucleophilic substitution on bromobenzene is difficult

14. Sulphide RSR’
The disconnection approaches for the sulphides are similar to the ethers as we
only replaced heteroatom ‘O’ with ‘S’

15. Two group C-X disconnection
1,1-Difunctionalized compounds:

16. 1,2-Disconnection:

17. 1,3-Disconnection:

18. Reference
Warren SG, Wyatt P. Organic synthesis : the
disconnection approach. Chichester: J. Wiley & Sons,
Cop; 2013.
Thankyou for listening