Antiviral agents

A method for the treatment or prophylaxis of a enterovirus infection in a mammal, comprising administering to the animal an effective amount of a compound of formula I:

• or a salt or pharmaceutically acceptable derivatives thereof,
• where:
• Het is an optionally substituted 5- or 6-membered monocyclic heterocyclic radical or an optionally substituted 9- or 10-membered bicyclic heterocyclic radical;
• A is O, S, NH, N(C1-6alkyl), CH2O, a direct bond or a bivalent heterocyclic radical of the formula:
• where one or more of the carbon atoms within the radicals (b-1) to (b-4) may be optionally substituted with C1-6alkyl or two carbon atoms in the radicals (b-1) to (b-4) may be bridged with a C2-4alkylene radical, m and n are each independently integers of 1 to 4 inclusive with the proviso that the sum of m and n in radicals (b-1) to (b-4) is 3, 4 or 5;
• Z is N or CR6, where R6 is hydrogen, hydroxy, C1-6alkyl, C1-6alkoxy or amino;
• ZN is O, S, CHR7 or NR8, where R7 is hydrogen, hydroxy, C1-6alkyl, C1-6alkoxy or amino and R8 is hydrogen or C1-6alkyl;
• R4 is hydrogen or C1-6alkyl;
• R5 is hydrogen, hydroxy, C1-6alkyl or C1-6alkoxy;
• Alk is C1-7alkylene or a direct bond;
• W is O, S, OCH2, a direct bond or NR9, where R9 is hydrogen or C1-6alkyl;
• X1, X2 and X3 are each independently selected from N and CR, where R is hydrogen, halogen, hydroxy, C1-6alkyl or C1-6alkoxy;
• and
• B is a five or six membered unsaturated heterocyclic ring, substituted with at least one substituent selected from R10, OR10, SR10 and NR9R10, where R10 is C1-6alkyl, haloC1-6 alkyl, C1-6 alkenyl, haloC1-6 alkenyl, C1-6 alkynyl or haloC1-6 alkynyl;
• with the proviso that when Alk is a direct bond and A is O, S, CH2O or a direct bond, then W is not O, S, OCH2 or a direct bond.

A method for the treatment or prophylaxis of a enterovirus infection in a mammal, comprising administering to the mammal an effective amount of a composition comprising a compound of formula II:

• wherein:
• R1 is hydrogen, C1-4alkyl, halo, hydroxyl, mercapto, trifluoromethyl, amino, mono or di(C1-4alkyl)amino, cyano, formyl, —CH═NO—C1-4alkyl, C1-4alkoxy, C1-4haloalkoxy, aryloxy, C1-4alkylthio, or aryl;
• Y is O, S, NH or NMe;
• Z is CH or N;
• Alk is C1-6alkylene;
• and
• R11 is OR10 or SR10, where R10 is C1-4alkyl;
• or a pharmaceutically acceptable salt thereof, together with a pharmaceutically acceptable carrier.