N,N-Dimethylmethyleneammonium iodide, commonly known as Eschenmoser's salt, is a specialized reagent in organic synthesis serving as an electrophilic source of the iminium ion (CH₂=NMe₂⁺). It is primarily employed in Mannich-type reactions and related transformations to introduce aminomethyl groups to nucleophilic substrates, enabling the formation of β-amino carbonyl compounds, enamines, and various heterocycles. This compound plays a crucial role in the pharmaceutical industry for assembling complex drug scaffolds, in agrochemical synthesis for pesticides and dyes, and as an intermediate in polymer modification to enhance material properties. Its applications extend to fine chemical production where precise functional group introductions are required.