Dimethyl Sulfoxide → Benzopyran

Participants

Reaction Steps

(±) 1,5-Dimethoxy-2′-isopropenyl dihydrofuroanoxanthone (107). DMSO (118 mL) was added to a mixture of (106) (1.21 g, 3.56 mmol), Pd[(CH3CN)4BF)2] (0.79 g, 1.78 mmol) and benzoquinone (recrystallized from EtOH, 3.84 g, 35.6 mmol). The solution was stirred 36 h, then poured into a separatory funnel containing CH2Cl2 (400 mL), and washed with H2O (2×300 mL). The layers were separated and the H2O layer was washed with CH2Cl2 (200 mL). The organic layers were combined and washed with sat. NaCl (200 mL), dried (Na2SO4) and concentrated under reduced pressure. The crude product was purified by column chromatography (50% EtOAc/hex), loading the product on the column in a minimum amount of CH2Cl2 to afford 0.15 g chromene (12%) and then 0.97 g (81%) of benzofuran (107) as a white solid. (LH-64-50).

Provenance & Evidence