General description
N-Chloro Succinimide (NCS) is a versatile and convenient
reagent to chlorinate organic compounds by additions or electrophilic
substitution.
Advantages over other reagents such as chlorine
itself, chloramine T or sulfury chloride:
- The ease of handling of the reagent itself
- The mild reaction conditions of its use
- The easy removal of Succinimide after the chlorination step.
Applications:
- Chlorination in carbonyl and carbonyl compounds :
Enolates and enol ethers of ketones and esters are chlorinated
in the ά -position. With suitable chiral auxiliaries present,
the reaction can proceed with high diasteroselectivity.
- Chlorination of sulfides and sulfoxides:
NCS is the best reagent to transform sulfides into
ά -Chloro sulfides, which are versatile intermediates,
for example for the preparation of aldehydes and ketones. Variations
of these reactions involve the degradation of carboxylic acids
to ketones (via ά -sulfination, reaction with NCS and hydrolysis)
and the removal of the 1, 3-dithiane protective group.
-
Research with vinylic and acetylenic
compounds:
Organometallic derivatives of vinylic compounds
are readily converted into the corresponding vinyl chlorides
4.
Chlorinations of aromatic compounds:
Electron-rich
heterocycles such as thiophenes, pyrroles and indoles can be chlorinated
in the ά
-position; the combination of NCS and dimehyl sulfide has been used
to chlorinate phenols
in ά -position.
Handling:
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