Editing Alkylation (section)

==Nucleophilic alkylating agents==
'''Nucleophilic alkylating agents''' deliver the equivalent of an [[alkyl]] [[anion]] ([[carbanion]]). The formal "alkyl anion" attacks an [[electrophile]], forming a new [[covalent bond]] between the alkyl group and the electrophile. The counterion, which is a cation such as lithium, can be removed and washed away in the [[Work-up (chemistry)|work-up]]. Examples include the use of [[organometallic compound]]s such as [[Grignard reagent|Grignard (organomagnesium)]], [[organolithium]], [[organocopper]], and [[organosodium]] reagents. These compounds typically can add to an electron-deficient carbon atom such as at a [[carbonyl group]]. Nucleophilic alkylating agents can displace [[halide]] substituents on a carbon atom through the [[SN2]] mechanism. With a [[Catalysis|catalyst]], they also alkylate alkyl and [[Aryl group|aryl]] halides, as exemplified by [[Suzuki coupling]]s.
[[File:Katalysezyklus-Kumada-Kupplung.png|thumb|upright=2.0|The [[Kumada coupling]] employs both a nucleophilic alkylation step subsequent to the oxidative addition of the aryl halide (L = [[Ligand]], Ar = [[Aryl]]). The starting material, an aryl bromide (Ar-Br) reacts with nickel with ligands (NiL<sub>2</sub>). Then, a Grignard reagent (R-MgBr) alkylates the nickel center, replacing the bromide ligand (Br) with an alkyl ligand (R). This nickel-aryl-alkyl complex undergoes rearrangement and reductive elimination to expel an alkylated aryl (Ar-R). The outcome of this reaction is that the aryl group (Ar) is alkylated with an alkyl group (R), replacing bromide (Br), creating an alkylated aryl (Ar-R), the intended product. The bromide is expelled as magnesium bromide (MgBr<sub>2</sub>). Nickel with ligands (NiL<sub>2</sub>) acts as the catalyst, being reused multiple times.]] The SN2 mechanism is not available for aryl substituents, where the trajectory to attack the carbon atom would be inside the ring. Thus, only reactions catalyzed by organometallic catalysts are possible.{{cn|date=January 2025}}