Organomagnesium halides (Grignard reagents, RMgX) add to polarized multiple bonds, most classically to aldehydes and ketones, to form a new carbon–carbon bond and, after hydrolysis, an alcohol. The reagent is prepared from an organic halide and magnesium metal; in solution it exists as a Schlenk equilibrium among RMgX, R2Mg, and MgX2, and the addition step is nucleophilic transfer of the organic group to the electrophilic carbon ^[1]. The same organomagnesium species alkylate or arylate other electrophiles, including epoxides, esters (with double addition), carbon dioxide, and activated carbon–halogen or carbon–fluorine sites on extended π systems such as fluorographene ^[2]. Sequential Staudinger/aza-Wittig/Grignard sequences use the addition to an in situ imine as the C–C-forming step toward iminosugars ^[3]. The concept is bounded as the reactivity of the C–Mg bond toward electrophiles. Transition-metal-catalyzed coupling of Grignard reagents (Kumada coupling) is a related but distinct process in which the elementary C–C bond-forming step occurs at the metal, not by direct polar addition of RMgX to a carbonyl ^[1].