How is N-(3',6'-Dihydroxy-3-oxo-3H-spiro[2-benzofuran-1,9'-xanthen]-6-yl)-2-iodoacetamide (CAS: 73264-12-7) typically synthesized?

N-(3',6'-Dihydroxy-3-oxo-3H-spiro[2-benzofuran-1,9'-xanthen]-6-yl)-2-iodoacetamide is typically synthesized via a multi-step reaction involving the iodination of a suitable precursor, followed by coupling with an acetylenic moiety. Commonly, the synthesis involves the use of N-bromosuccinimide (NBS) as a brominating agent and potassium iodide (KI) as a catalyst. High selectivity and yield are achieved under optimized reaction conditions, including temperature and solvent selection.