3-Iodopyridine is a halogenated heterocyclic compound with the molecular formula C5H4IN. It is a versatile organic building block characterized by an iodine atom attached to the pyridine ring at the 3-position. This structure makes it a valuable precursor for various cross-coupling reactions, particularly Suzuki-Miyaura and Stille couplings, due to the good reactivity of the C-I bond. Its primary application is as a key intermediate in organic synthesis, especially in the pharmaceutical and agrochemical industries. It is used to construct more complex molecules, including ligands for catalysts and active pharmaceutical ingredients (APIs). For instance, it serves as a crucial synthon in the synthesis of nicotinic acetylcholine receptor ligands and other biologically active nitrogen-containing heterocycles. As a reagent, it should be handled with care, typically under inert atmosphere due to its sensitivity. It is commercially available and widely used in research and development for introducing the 3-pyridyl moiety into target molecules through efficient metal-catalyzed transformations.