Sulfuric Acid → 8-(Trifluoromethyl)-2,3-dihydro-4H-1-benzopyran-4-one

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Reaction Steps

A solution of Example 18A (24.1 g, 103 mmol) and sulfuric acid (12 mL, 225 mmol) in trifluoroacetic acid (200 mL) was stirred at room temperature for 3 days. The reaction mixture was poured into ice-water and extracted with dichloromethane (2×200 mL). The organic layers were combined, washed with a saturated aqueous NaHCO3 solution (200 mL), dried (MgSO4), filtered, and concentrated. Silica gel chromatography (15% EtOAc/hexanes) gave the title compound (7.21 g, 33.4 mmol, 32%). MS (DCI/NH3) m/z 216 (M+NH4—H2O)+.

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