| abstract |
Compound represented by the following structural formula: or a pharmaceutically acceptable salt thereof, in which: Y is a covalent bond or a substituted or unsubstituted straight chain hydrocarbon group; R1 and R2 are independently H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group; R3 and R4 are independently H, an aliphatic group, a substituted aliphatic group, an aryl group or a substituted aryl group; R5-R6 are independently H or an aliphatic group; and Z is = O or = S; Whenever Y is ¿CH2-, R3 and R4 are both phenyl and R5-R6 are all ¿H, then R1 and R2 are not both phenyl. |