The present inventors have found that (ethyne-1,2-diyl)bis(isobenzofuran-1,3-diones), such as 5,5′-(ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione), may be obtained in a high yield in a one-step procedure by employing a Sonogashira coupling to react a chloro-, bromo-, or iodoisobenzofuran-1,3-dione, such as 5-chloro-, 5-bromo-, or 5-iodoisobenzofuran-1,3-dione, with acetylene, i.e. ethyne. By employing a one step procedure and by avoiding aqueous work-up, causing hydrolysis of the anhydride moieties, a (ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione), such as 5,5′-(ethyne-1,2-diyl)bis(isobenzofuran-1,3-dione), may be obtained in significantly higher yield and shorter process time compared to known processes.
