Griseolic acid monoesters, their preparation and use

Abstract From the Canadian patent

Monoester griseolic acid derivatives of formula (I): (I), (in which: R1 and R2 are the same or different and each represents a hydrogen atoms, hydroxy groups and protected hydroxy groups; R3 and R4 each represents a hydrogen atom, or together represent an extra carbon-carbon bond between the two carbon atoms to which they are attached; one of R and R represents a hydrogen atom and the other represents a carboxy-protecting group removable in the biochemical environment of the human eye); and pharmaceutically acceptable salts thereof have been found to have valuable properties in the treatment of ophthalmic disorders, They may be prepared by the selective esterification of the appropriate …