6-(((2,5-Dioxopyrrolidin-1-yl)oxy)carbonyl)-3-oxo-3H-spiro[isobenzofuran-1,9'-xanthene]-3',6'-diyl bis(2,2-dimethylpropanoate) 1g

6-(((2,5-Dioxopyrrolidin-1-yl)oxy)carbonyl)-3-oxo-3H-spiro[isobenzofuran-1,9'-xanthene]-3',6'-diyl bis(2,2-dimethylpropanoate) 1g