N-[(S)-(4-Nitrophenoxy)phenoxyphosphinyl]-L-alanine 1-Methylethyl ester

N-[(S)-(4-Nitrophenoxy)phenoxyphosphinyl]-L-alanine 1-Methylethyl Ester is an intermediate in the synthesis of Sofosbuvir (R)-Phosphate (S675615), which is an impurity of PSI-7977 (P839640), a prodrug that is metabolized to the active antiviral agent 2''-deoxy-2''-α-fluoro-β-C-methyluridine-5''-monophosphate and is currently being investigated in phase 3 clinical trials for the treatment of hepatitis C. Studies have profiled PSI-7977 as a nucleotide inhibitor of hepatitis C virus, exerting selective inhibitory effects towards HCV NS5B polymerase.