(2,5-dioxopyrrolidin-1-yl) 2-(3,4-dimethoxyphenyl)acetate

bis(2,5-dioxopyrrolidin-1-yl) 2-oxobutanedioate

(2,5-dioxopyrrolidin-1-yl) 3-methoxybenzoate

(2,5-dioxopyrrolidin-1-yl) 2-chlorobenzoate

(2,5-dioxopyrrolidin-1-yl) 4-chlorobenzoate