Spirocyclic compounds such as hepatitis C virus (HCV) NSR3 protease inhibitors containing a spirocyclic moiety, to uses of such compounds for the treatment of HCV infection. Claim 1: A compound of formula (1) or a pharmaceutically acceptable salt thereof, wherein A is selected from the group consisting of C₁₋₈ alkyl groups,C₂₋₈ alkenyl,1. C 83228331 asphalt；internally substituted C₁₋₈ alkyl, internally substituted C₂₋₈ alkenyl, internally substituted C₂₋₈ alkynyl, C₃₋₈ cycloalkyl,internally substituted C₃₋₈ cycloalkyl, Si (RA) ₃,If (RA) 832223 (ch8323)；If (RA) (ch832323) 83222,Yes (ch832323) 8323,a. Arilo and bicycle members are composed of 7, 8, 9 and 10 members, of which a (RA) 8323；If (RA) 832223 (ch8323)；If (RA) (ch832323) 83222,Yes (ch832323) 8323,internally substituted C₁₋₈ alkyl, internally substituted C₂₋₈ alkenyl, internally substituted C₂₋₈ alkynyl, internally substituted C₃₋₈ cycloalkyl, aryl and bicyclic contain 0, 1, 2 or 3 heteroatoms independently selected from the group consisting of B, O, S and N, each A aryl is independently selected from the group consisting of 5 and 6 member aromatic rings and 7, 8, 9 and 10 member bicyclic aromatic rings, said A is substituted by 0, 1, 2, 3 or 4 RA substituents； each RA is independently selected from the group consisting of H, F, Cl, Br, I, OH, C₁₋₆ alkyl,C₁₋₆ haloalkyl,C₁₋₆ alkoxy,alquil C (NH)phenyl, naphthyl, C₃₋₈ cycloalkyl,halo (alcoxi C)-O (C₁₋₆ alkyl),SH, S (C₁₋₆ alkyl),NH.8322；-NH (alquilo OLD),-N (C₁₋₆ alkyl) ₂,-C (O) (C₁₋₆ alkyl),-CONH₂,-SO₂NH₂,No.8322；CN -CF₃；-CHF₂,-CH₂F, -OCHF₂,-OCF8323,-OCH₂F, -SO₂ (alquilo C₁₋₆),-S (O) (C₁₋₆ alkyl),- (C₁₋₆ alkyl) S (O) (C₁₋₆ alkyl),-S (O) ₂ (C₁₋₆ alkyl),- (C₁₋₆ alkyl) S (O) ₂ (C₁₋₆ alkyl),- (C₁₋₆ alkyl) N (C₁₋₆ alkyl) SO₂ (C₁₋₆ alkyl),-N (alquil C) SO (alquilo C)-SO₂N(alquilo C₁₋₆)₂,- (alquil C) SO N (alquilo C)-NHCOO (C₁₋₆ alkyl),-NHCO (alquilo C)-NHCONH (C₁₋₆ alkyl),-CO₂ (alquilo C₁₋₆),-C (O) N (alquilo C)- (alquil C) - (cicloalquilo C)- (alquil C) -O- (alquil C)
