In a 100 mL round bottomed flask was placed 5-chloro-2′-pyridin-4-yl-6′,7′-dihydro-3H,5′H-spiro[2-benzofuran-1,4′-[1]benzothiophen]-3-one (0.714 g, 1.94 mmol) (including side product) along with 1,4-dioxane (20 mL) and acetonitrile (10 mL). To the mixture was added a suspension of potassium persulfate (1.85 g, 6.84 mmol) and copper (II) sulfate pentahydrate (180 mg, 0.72 mmol) in water (20 mL) followed by γ-collidine (0.897 mL, 6.79 mmol). The mixture was stirred for 3.5 hr at 80° C. Again, to the mixture was added a suspension of potassium persulfate (1.96 g, 7.25 mmol) and copper(II) sulfate pentahydrate (20 mg, 0.08 mmol) in water (20 mL, 1000 mmol) followed by γ-collidine (0.9 mL, 7 mmol) and 1,4-dioxane (10 mL, 100 mmol). The mixture was stirred for an additional 16 hr at 80° C. The mixture was allowed to cool to rt and then diluted with EtOAc (50 mL). Insoluble materials were removed by filtration through a celite pad and the aqueous phase was separated from the filtrate. The aqueous phase was extracted with EtOAc (50 mL). The combined organic phases were dried over anhydrous MgSO4. Insoluble materials were removed by filtration and the filtrate was concentrated under reduced pressure. The residue was purified by HPLC (FA) to obtain the title compound (22.5 mg; 3%) as an off-white crystalline solid. LCMS: (FA) ES+ 382, 384; 1H NMR (400 MHz, d6-DMSO) δ ppm 8.59 (dd, 2H), 8.07 (d, 1H), 7.89 (dd, 1H), 7.77 (d, 1H), 7.71 (dd, 2H), 7.46 (s, 1H), 2.47-3.05 (m, 4H).
