COMPOSIZIONE FARMACEUTICA CONTENENTE 3,4-DI-IDRO-3-OSSO-2-CHINOSSALINE

A pharmaceutical composition characterized by as active ingredient a 3,4-dihydro-3-oxoquinoxaline of the formula: wherein R and R are individually H, NO2 or CH3O; R1 and R are individually H, NO2, CH3O or halo such that at least one of R, R , R and R is other than H, such that if neither R and R is NO2 or CH3O, both RR and R are individually halo and both R and R are H, and such that one of R and R is CH3O only if one of R, R , R and R is NO2; R is C1-C4 alkyl, C3-C6 cycloalkyl, C3-C4 alkenyl, H or 2-chloroethyl; and n is 0 or 2, e.g. ethyl 6,7-dibromo- 3,4-dihydro-3-oxo-2- quinoxaline carboxylate, and excipients is useful for suppressing viral infection in mammals. All but one of the quinoxalines disclosed are new. The compounds are prepared by reacting an o-phenylene diamine with an alpha -ketodibasic acid. Certain of the compounds are prepared by reacting a 6-nitro-4,5- disubstituted aniline with an alkyl malonyl chloride followed by annelation in the presence of sodium ethoxide and then treatment with phosphorus trichloride.