3-Hydroxyadamantane-1-carboxylic acid is a functionalized adamantane derivative. It serves as a crucial synthetic intermediate in the preparation of various pharmacologically active compounds. Its structure combines the rigid, lipophilic adamantane cage with both a carboxylic acid and a hydroxyl group, making it a versatile building block for medicinal chemistry. The primary and most significant application of this compound is in the synthesis of antiviral drugs, particularly those targeting influenza. It is a key precursor in the manufacturing of Baloxavir marboxil, a novel cap-dependent endonuclease inhibitor approved for the treatment of influenza A and B. The adamantane core is essential for the drug's mechanism of action and pharmacokinetic properties. Beyond its role in antiviral API synthesis, 3-hydroxyadamantane-1-carboxylic acid is also explored in the development of other therapeutic agents, including treatments for neurodegenerative diseases, due to the blood-brain barrier permeability often associated with adamantane derivatives. It is a high-value intermediate in fine chemical and pharmaceutical production.