Are there alternatives to 4,4'-[(9,10-Dioxo-9,10-dihydroanthracene-2,6-diyl)bis(oxy)]dibutanoic acid in synthesis?

There are several alternatives to 4,4'-[(9,10-Dioxo-9,10-dihydroanthracene-2,6-diyl)bis(oxy)]dibutanoic acid in synthesis, including other butanoic acids with similar functional groups, such as 4,4'-[(9,10-Dioxy-9,10-dihydroanthracene-2,6-diyl)bis(oxy)]dibutanoic acid. Isomers and analogs like 4,4'-[(9,10-Dihydroxy-9,10-dihydroanthracene-2,6-diyl)bis(oxy)]dibutanoic acid can also be considered. Alternative reagents such as esters, anhydrides, or other functionalized compounds can be used as substitutes.