A process for the manufacture of an antiviral compound of general formula or a pharmaceutically acceptable salt thereof wherein - R 1 is selected from an alkyl group having 1 to 12 carbon atoms which is optionally substituted by a halogen atom or a hydroxyl group, a cycloalkyl group having 3 to 12 carbon atoms which is optionally substituted by a halogen atom or a hydroxyl group, an aryl group, an alkylaryl group, or a cycloheteroalkyl group having 3 to 12 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms optionally substituted by a halogen atom or hydroxyl group, a cycloalkyl group having 3 to 6 carbon atoms which is optionally substituted by a halogen atom or hydroxyl group, a phenyl, a benzyl, a morpholine, or an imidazolyl, more preferably an alkyl group having 1 to 4 carbon atoms, a cyclohexyl, a phenyl or a benzyl, and which comprises the steps of: Step 1.: diazotization of a compound of general formula: wherein R 2 is selected from hydrogen, thereby forming a diazonium compound of general formula or a pharmaceutically acceptable salt thereof: wherein R 2 has the same meaning as defined here above, Step 2.: condensation reaction of the diazonium compound of general formula or a pharmaceutically acceptable salt thereof, as obtained in Step 1, with at least one α-nitroester of general formula, as shown below, wherein - R 3 is independently selected from a group consisting of: • - -OR 5 wherein R 5 is an alkyl group having 1 to 24 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group; • - -R 6 wherein R 6 is an alkyl group having 1 to 12 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group, - R 4 is an alkyl group having 1 to 24 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group; an alkenyl group. - R 1 is selected from an alkyl group having 1 to 12 carbon atoms which is optionally substituted by a halogen atom or a hydroxyl group, a cycloalkyl group having 3 to 12 carbon atoms which is optionally substituted by a halogen atom or a hydroxyl group, an aryl group, an alkylaryl group, or a cycloheteroalkyl group having 3 to 12 carbon atoms, preferably an alkyl group having 1 to 8 carbon atoms optionally substituted by a halogen atom or hydroxyl group, a cycloalkyl group having 3 to 6 carbon atoms which is optionally substituted by a halogen atom or hydroxyl group, a phenyl, a benzyl, a morpholine, or an imidazolyl, more preferably an alkyl group having 1 to 4 carbon atoms, a cyclohexyl, a phenyl or a benzyl, and which comprises the steps of: Step 1.: diazotization of a compound of general formula: wherein R 2 is selected from hydrogen, thereby forming a diazonium compound of general formula or a pharmaceutically acceptable salt thereof: wherein R 2 has the same meaning as defined here above, Step 2.: condensation reaction of the diazonium compound of general formula or a pharmaceutically acceptable salt thereof, as obtained in Step 1, with at least one α-nitroester of general formula, as shown below, wherein Step 1.: diazotization of a compound of general formula: wherein R 2 is selected from hydrogen, thereby forming a diazonium compound of general formula or a pharmaceutically acceptable salt thereof: wherein R 2 has the same meaning as defined here above, Step 2.: condensation reaction of the diazonium compound of general formula or a pharmaceutically acceptable salt thereof, as obtained in Step 1, with at least one α-nitroester of general formula, as shown below, wherein - R 3 is independently selected from a group consisting of: • - -OR 5 wherein R 5 is an alkyl group having 1 to 24 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group; • - -R 6 wherein R 6 is an alkyl group having 1 to 12 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group, • - -OR 5 wherein R 5 is an alkyl group having 1 to 24 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group; • - -R 6 wherein R 6 is an alkyl group having 1 to 12 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group, - R 4 is an alkyl group having 1 to 24 carbon atoms which is optionally substituted by a hydroxyl group, an amine group, a halogen atom, an aryl group or an aralkyl group; an alkenyl group.