This compound, with CAS number 376608-74-1, is a complex nucleoside analogue derivative. Its chemical name is 2-[(3aR,4S,6R,6aS)-6-[(5-Amino-6-chloro-2-(propylthio)pyrimidin-4-yl)amino]tetrahydro-2,2-dimethyl-4H-cyclopenta[d][1,3]dioxol-4-yl]oxy]ethanol. It features a modified sugar moiety (a cyclopentane ring fused with a dioxolane) linked to a substituted pyrimidine base via an amino group. The structure contains key functional groups including an amino group, a chloro substituent, a propylthio group, and a terminal ethanoloxy chain. This molecule is a critical advanced intermediate in the synthesis of Sofosbuvir (GS-7977), a groundbreaking direct-acting antiviral agent and a key component of highly effective treatments for chronic Hepatitis C virus (HCV) infection. Sofosbuvir is a nucleotide analog prodrug inhibitor of the HCV NS5B RNA-dependent RNA polymerase. The specific stereochemistry and functional groups in this intermediate are essential for the final drug's potency and selectivity. As a high-value pharmaceutical intermediate, its synthesis and purity are of paramount importance in the manufacturing process of Sofosbuvir. Handling requires standard precautions for fine chemicals, and it should be stored under inert conditions to maintain stability.