Efficient Synthesis of 3-Phenylnaphtho[2,3-b]furan-4,9-diones in Water and Their Fluorimetric Study in Solutions

A simple and efficient protocol has been developed for the synthesis of 3-phenylnaphtho[2,3-b]furan-4,9-diones by domino reaction of a-bromonitroalkenes to 2-hydroxynaphthalene-1,4-dione. With the optimal reaction condi- tions [NaOAc （120 mol%）, water, 70 ~C, 7 h], the scope of the domino reaction was explored and the green ap- proach provided the desired products in moderate to good yields at elevated temperature under aqueous-mediated conditions. A mechanistic rationalization for this reaction is also provided. The absorption characteristics of the compounds were examined by UV-Vis spectra and fluorescence spectroscopy. All compounds were fluorescent in solution emitting at blue light （432--433 nm）, green light （512--536 nm）, or yellow light （591 nm）.