| abstract |
A compound selected from the group consisting of a 5,6-dihydro-alpha-pyrone of formula (I):wherein bond a is oriented either <CUSTOM-CHARACTER FILE="US06197811-20010306-P00001.TIF" ID="CUSTOM-CHARACTER-00001"> or <CUSTOM-CHARACTER FILE="US06197811-20010306-P00002.TIF" ID="CUSTOM-CHARACTER-00002">;X is O or NH;R1 is selected from the group consisting of:a group R3(O)C- wherein R3 is selected from the group consisting of: (i) a group of formula R4-CH=CH- wherein R4 is C1-C20 alkyl, C2-C20 alkenyl, an aryl group,or a 5- or 6-membered unsaturated heterocyclic ring containing one or two O, N or S atoms, (ii) C2-C20 alkyl;and (iii) an aryl group or a substituent which is a fused ring system of formula (1) or (2): wherein each of R' and R'', which are the same or different and may occupy any position on ring a or ring b of said fused ring system, is H or C1-C6 alkyl;a group ArCH2- wherein Ar is an aryl group; anda group R5O-CH2- wherein R5 is C1-C6 alkyl optionally interrupted by one or two O atoms; andR2 is CH3 or, when R1 is a group of formula (A) as defined below, R2 is R6OOC- or R6NOC- wherein R6 is C1-C6 alkyl;and the pharmaceutically and veterinarily acceptable salts and esters thereof; with the exception of compounds wherein bond a is oriented <CUSTOM-CHARACTER FILE="US06197811-20010306-P00001.TIF" ID="CUSTOM-CHARACTER-00003">,X is O and R1 is a group of formula (A): wherein R11 and R21 are H when R2 in formula (I) is CO2H or CH3, or one of R11 and R21 is H and the other is OH when R2 in formula (I) is CO2H. |