chloride used as a catalyst. As biphenyl is a solid crystal it is solved in 1,2-dichloroethane (DCE). The mixture of chloroacetyl chloride and aluminium chloride is also used in a solution with DCE. To separate the product from the other compounds the outcoming reaction mixture is treated with 2N HCl solution. In the next step, the symmetrically acetylated product from the first step reacts with an N-methoxycarbonyl dipeptide in an esterification reaction. The dipeptide consists of the amino acids L-proline and L-valine and is solved in acetonitrile (MeCN). While the amino terminus of valine is protected by the methoxycarbonyl group the carboxy terminus of proline reacts with the product of step one forming the esterified product of both chemicals. In this reaction triethylamine works as a basic solvent. As a final step, the present molecule reacts with ammonium acetate in water forming the imidazole heterocycles on both sides of the molecule. Another option is to esterify it with boc-protected proline first, then form the imidazole heterocycles with ammonium acetate and add valine in the end after acidic deprotection of prolines N-terminus. In both cases, the final product is the daclatasvir free base. In the drug, daclatasvir is present in the hydrochloride salt form. Society and culture It is on the World Health Organization's List of Essential Medicines. Economics In December 2014, Bristol Myers Squibb announced that it would offer the drug for sale at different prices in different countries, depending on the level of economic development, and that it would license the drug to generics manufacturers for sale in the developing world. As of January 2016, a twelve-week course cost around $63,000 in the US, around $39,000 in the UK, around $37,000 in France, and $525 in Egypt. Research Daclatasvir has been tested in combination regimens with pegylated interferon and ribavirin, as well as with other direct-acting antiviral agents including asunaprevir and sofosbuvir. References External links NS5A inhibitors Carbamates Imidazoles Pyrrolidines Biphenyls Withdrawn drugs World Health Organization essential medicines Wikipedia medicine articles ready to translate