Butyl-lithium is principally valued as an initiator for the ionic polymerization of dienes,such as butadienes.
The reaction is called "carbolithiation".
C4H9LI + CH2=CH-CH=CH2 → C4H9-CH2-CH=CH-CH2Li
Butyl-lithium is a strong base and also a powerful nucleophile and reductant,depending on the other reactants.
So, let us study the reaction of the compound below with BuLi.
As it acts as a reductant, we first draw the result step by step.
Example beow:
Hence, we will first proceed to let BuLi act as a reductant.(grignard)
Then, CO2 added and stepwise accordingly protonation is done.