2,2-bis(4-chlorophenyl)-5-methyl-1,3-dioxane-5-carboxylic 2,4,6-trichlorobenzoic anhydride

3-methyl-1,5-dioxaspiro[5.6]dodecane-3-carboxylic acid

2,4,6-trichlorobenzoic 5'-methylspiro[fluorene-9,2'-[1,3]dioxane]-5'-carboxylic anhydride