Editing Organolithium reagent (section)

====Carbolithiation reactions====
As nucleophiles, organolithium reagents undergo carbolithiation reactions, whereby the carbon-lithium bond adds across a carbon''–''carbon double or triple bond, forming new organolithium species.<ref name=Intracarbolithiation>{{cite book| last1 = Fananas | first1 = Francisco | last2 = Sanz | first2 = Roberto| chapter = Intramolecular carbolithiation reactions| title = PATAI'S Chemistry of Functional Groups.| publisher = John Wiley & Sons, Ltd | year = 2009| isbn = 9780470682531 | doi = 10.1002/9780470682531.pat0341}}</ref> This reaction is the most widely employed reaction of organolithium compounds. Carbolithiation is key in anionic polymerization processes, and [[n-butyllithium|''n''-butyllithium]] is used as a catalyst to initiate the polymerization of [[styrene]], butadiene, or isoprene or mixtures thereof.<ref name=Hsieh>Heinz-Dieter Brandt, Wolfgang Nentwig1, Nicola Rooney, Ronald T. LaFlair, Ute U. Wolf, John Duffy, Judit E. Puskas, Gabor Kaszas, Mark Drewitt, Stephan Glander "Rubber, 5. Solution Rubbers" in Ullmann's Encyclopedia of Industrial Chemistry, 2011, Wiley-VCH, Weinheim. {{doi|10.1002/14356007.o23_o02}}</ref><ref name=anionicpolymer>
{{cite book| last1 = Baskaran | first1 = D.| last2 = Müller | first2 = A.H.| chapter = Anionic Vinyl Polymerization| title = Controlled and living polymerizations: From mechanisms to applications| publisher = Wiley-VCH Verlag GmbH & Co. KGaA| location = Weinheim, Germany| year = 2010| doi = 10.1002/9783527629091.ch1| isbn = 9783527629091}}</ref>

:[[File:Anionic polymerization of styrene initiated by sec-BuLi.png|450px|Anionic polymerization of styrene initiated by ''sec''-butyllithium|center]]

Another application that takes advantage of this reactivity is the formation of carbocyclic and heterocyclic compounds by [[Intramolecular reaction|intramolecular]] carbolithiation.<ref name=Intracarbolithiation /> As a form of anionic cyclization, intramolecular carbolithiation reactions offer several advantages over [[radical cyclization]]. First, it is possible for the product cyclic organolithium species to react with electrophiles, whereas it is often difficult to trap a radical intermediate of the corresponding structure. Secondly, anionic cyclizations are often more regio- and stereospecific than radical cyclization, particularly in the case of 5-hexenyllithiums. Intramolecular carbolithiation allows addition of the alkyl-, [[vinyllithium]] to triple bonds and mono-alkyl substituted double bonds. Aryllithiums can also undergo addition if a 5-membered ring is formed. The limitations of intramolecular carbolithiation include difficulty of forming 3 or 4-membered rings, as the intermediate cyclic organolithium species often tend to undergo ring-openings.<ref name=Intracarbolithiation /> Below is an example of intramolecular carbolithiation reaction. The lithium species derived from the lithium–halogen exchange cyclized to form the vinyllithium through 5-exo-trig ring closure. The vinyllithium species further reacts with electrophiles and produce functionalized cyclopentylidene compounds.<ref name=intra18>{{cite journal| title = Preparation and facile cyclization of 5-alkyn-1-yllithiums| author = Bailey, W.F.| journal = Tetrahedron Lett.| year = 1989| volume = 30| issue = 30| pages = 3901–3904| doi = 10.1016/S0040-4039(00)99279-7 |display-authors=etal}}</ref>

:[[File:Intramolecular carbolithiation'.png|470px|A sample stereoselective intramolecular carbolithiation reaction|center]]