Boron tribromide → 6-Hydroxy-7-fluoro-2,2-dimethylthiochroman-4-one

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Reaction Conditions

Reaction Steps

To a solution of 6-methoxy-7-fluoro-2,2-dimethyl-thiochroman-4-one (Compound 203, 1.75 g, 7.29 mmol) in 25 mL CH2Cl2 cooled to -23° C. was added BBr3 (5.46 g, 21.8 mmol; 21.8 mL of a 1M solution in CH2Cl2) over a 10 minute period. After stirring for 23 hours at -230° C. the solution was warmed to 0° C. for 3 hours, and then cooled to -78° C. and quenched by the slow addition of 25 mL of H2O. Upon warming to room temperature the aqueous layer was extracted with CH2Cl2 and the combined organic layers were washed with saturated aqueous NaHCO3, H2O, and saturated aqueous NaCl before being dried over MgSO4. Removal of the solvents under reduced pressure, followed by column chromatography (10 to 20% EtOAc/hexanes) afforded 1.12 g (68%) of the title compound as a colorless solid. 1H NMR (300 MHz, CDCl3)δ: 7.82 (1H, d J=9.3 Hz), 6.97 (1H, d, J=10.4 Hz), 5.54 (1H, s), 2.86 (2H,s), 1.46 (6H, s).

Provenance & Evidence