(3R,4s)-4-Aminotetrahydrofuran-3-ol hydrochloride is a chiral, heterocyclic building block featuring both an amino and a hydroxyl group on a tetrahydrofuran ring. It is a key synthetic intermediate in the preparation of nucleoside analogs, particularly those with a locked or modified sugar moiety. This compound serves as a crucial precursor in the synthesis of various antiviral and anticancer nucleoside drugs. Its structural framework is essential for constructing modified nucleosides that act as chain terminators or inhibitors of viral polymerases. Research highlights its use in developing novel therapeutic agents targeting viral infections and certain cancers. As a versatile chiral synthon, it enables the introduction of the aminotetrahydrofuran core into complex molecules. Its availability as a hydrochloride salt enhances stability and handling for pharmaceutical synthesis.