Carbolithiation is the addition of an organolithium reagent across a carbon-carbon pi-bond. The organolithium reagents used in this transformation can be commercial (such as n-butyllithium) or can be generated through deprotonation or lithium-halogen exchange. Both inter- and intramolecular examples of carbolithiation exist and can be used in synthesis to generate complexity. Organolithiums are highly reactive chemicals and often the resulting organolithium reagent generated from the carbolithiation can continue to react with electrophiles or remaining starting material (resulting in polymerization). This reaction has been rendered enantioselective through the use of sparteine, which can chelate the lithium ion and induce chirality. Today, this is not a common strategy due to a shortage of natural sparteine. However, recent advances in the synthesis of sparteine surrogates and their effective application in carbolithiation have reactivated interest in this strategy. 
Another demonstration of this reaction type is an alternative route to tamoxifen starting from diphenylacetylene and ethyllithium: The capturing electrophile here is triisopropyl borate forming the boronic acid R–B(OH). The second step completing tamoxifen is a Suzuki reaction.
As a consequence of the high reactivity of organolithiums as strong bases and strong nucleophiles, the substrate scope of the carbolithiation is generally limited to chemicals that do not contain acidic or electrophilic functional groups.