In recent years, new changes have occurred in the treatment of chronic hepatitis C. Direct-acting antiviral agents have shown powerful efficacy in the treatment of active hepatitis C, and even refractory hepatitis C shows a high continuous virologic response. Among these direct-acting antiviral agents, sofosbuvir (SOF) has the advantages of short course of antiviral treatment and high response rate, and some patients with certain hepatitis C genotypes have no need to receive interferon therapy. This article introduces the mechanism of action, current status of clinical application, and major adverse effects of SOF, and points out its promising future in patients with refractory hepatitis C.

An improved manufacturing process for rivastigmine(1)was developed by performing the condensation reaction of m-hydroxyacetophenone(4)with N-ethyl-N-methyl carbamoyl chloride, then Corey-Bakshi-Shibata(CBS)chiral reduction to(R)-3-(1-hydroxyethyl)phenyl ethyl(methyl)carbamate(2)and then mesylation with methanesulfonyl chloride and nucleophilic substitution with dimethylamine, respectively. To be successful, a crucial reductive process in the conversion of ketone(3)to chiralalcohol(2)had to be correctly understood and optimized via orthogonal experiment. The whole improved process was convenient for operation and purification, with completion of the synthesis of rivastigmine and an overall yield of 88%.