Referring to a Heterocyclic Compound of formula (iii),Where R1 is H, or C1 - C3 alkyl R2 is alkyl C1 - C3 R3 is H or together with the carbon Atom that is bonded to form a Ring Spiro saturated with 4, 5 or 6 members.Preferred compounds are: [(1S) - 1 - ((2S) - 2 - [4 - (4 - {2 - [(3S, 7s and 9S) - 7.9 - dimethyl - 2 - ((2S) - 3 - methyl - 2 - {[(metiloxi) carbonyl] amino} butanoil - 6,10) - 2 - [4 - dioxa azaspiro,5] dec-3 il] - 1H imidazole - il - 4} - 4 - biphenyl) - 1H imidazole - 2 - yl] - 1 - pirrolidinil} carbonyl) - 2-methylpropyl] methylcarbamate (4,4 - bifenildiilbis {1h imidazole - 4.2 - diyl [(3S, 7s and 9S) - 7.9 - dimethyl - 610 - dioxa - 2 - azaspiro [4,5] decan - 3.2 - diyl] [(2S) - 3 - methyl - 1 - oxo - 1,2 - dimethyl biscarbamato butandiil})], [(1S) - 2 - methyl - 1 - ((2S) - 2 - [4 - (4 - {2 - [(3S) - 2 - ((2S) - 3 - methyl - 2 - {[(metiloxi) carbonyl] amino} butanoil) - 610 - dioxa - 2 - azaspiro - [4.5] dec-3 il] - 1H imidazole - il - 4} - 4 - bifenilil) - 1H imidazole - 2 - yl] - 1 - pirrolidinil} carbonyl methyl) propyl] carbamate, among others.It also relates to a Pharmaceutical composition. These antiviral compounds are useful in the treatment of Infections by hepatitis C virusREFERIDA A UN COMPUESTO HETEROCICLICO DE FORMULA (III), DONDE R1 ES H O ALQUILO C1-C3 R2 ES ALQUILO C1-C3 R3 ES H O JUNTO CON EL ATOMO DE CARBONO AL QUE ESTA UNIDO FORMA UN ANILLO ESPIRO SATURADO DE 4, 5 O 6 MIEMBROS. SON COMPUESTOS PREFERIDOS: [(1S)-1-({(2S)-2-[4-(4-{2-[(3S,7S,9S)-7,9-DIMETIL-2-((2S)-3-METIL-2-{[(METILOXI)CARBONIL]AMINO}BUTANOIL)-6,10-DIOXA-2-AZASPIRO[4,5]DEC-3-IL]-1H-IMIDAZOL-4-IL}-4-BIFENIL)-1H-IMIDAZOL-2-IL]-1-PIRROLIDINIL}CARBONIL)-2-METILPROPIL]CARBAMATO DE METILO, (4,4-BIFENILDIILBIS{1H-IMIDAZOL-4,2-DIIL[(3S,7S,9S)-7,9-DIMETIL-6,10-DIOXA-2-AZASPIRO[4,5]DECAN-3,2-DIIL][(2S)-3-METIL-1-OXO-1,2-BUTANDIIL]})BISCARBAMATO DE DIMETILO, [(1S)-2-METIL-1-({(2S)-2-[4-(4-{2-[(3S)-2-((2S)-3-METIL-2-{[(METILOXI)CARBONIL]AMINO}BUTANOIL)-6,10-DIOXA-2-AZASPIRO-[4
