Hydrochloric Acid → 2,2-dimethyl-3,4-dihydro-2H-1-benzopyran-7-ol

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A mixture of 7-hydroxy-2,2-dimethylchroman-4-one (500 mg, 2.60 mmol) and HCl (conc. 10 mL) in MeOH (30 mL) was stirred at 0° C. for 10 min, then zinc power (300 mg) was added slowly. After stirring at room temperature for 16 hrs, the solvents were removed under reduced pressure and the mixture was extracted with EtOAc (150×3 mL). The combined organic layers were washed with brine, dried over Na2SO4, filtered and concentrated. The residue was purified by reverse phase column flash (28%-35% MeCN in 0.5% NH4HCO3) to give target product of 2,2-dimethylchroman-7-ol (290 mg, 62%) as a brown yellow solid. LCMS (ESI) m/z: 177.1 [M−H]+; 1H-NMR (500 MHz, CDCl3): δ 6.89 (d, J=8.0 Hz, 1H), 6.34 (dd, J=8.5, 2.5 Hz, 1H), 6.27 (d, J=2.5 Hz, 1H), 4.70 (s, 1H), 2.69 (t, J=13.5, 7.0 Hz, 2H), 1.77 (t, J=13.5, 7.0 Hz, 2H), 1.32 (s, 6H).

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