Methyl 4-iodobutanoate is primarily used in organic synthesis as a versatile building block for the preparation of more complex molecules. It serves as an intermediate in the production of pharmaceuticals, where it can be utilized to introduce the butanoate moiety into target compounds. The iodine atom in the molecule makes it a valuable substrate for various coupling reactions, such as Suzuki or Sonogashira couplings, enabling the formation of carbon-carbon bonds. Additionally, it is employed in the synthesis of fine chemicals and agrochemicals, where its reactivity allows for the creation of diverse functionalized products. Its ester group also makes it a useful precursor in the synthesis of esters, acids, and alcohols through hydrolysis or reduction reactions.