Trifluoroacetic acid → 6-bromo-1H,3H-naphtho[1,8-cd]pyran

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Reaction Steps

To 6-bromo-1H,3H-naphtho[1,8-cd]pyran-1,3-dione (1.5 g, 5.4 mmol) in ethanol (10 mL) was added sodium borohydride (0.41 g, 10.8 mmol) and the mixture stirred at room temperature for 1 h. The reaction was quenched with 3M hydrochloric acid and extracted into dichloromethane. The combined organic extracts were dried (Na2SO4) and concentrated in vacuo. The residue was dissolved in dichloromethane and trifluoroacetic acid (1.05 mL, 13.53 mmol) and triethylsilane (4.3 mL, 27 mmol) added. After stirring for 5 min at room temperature, the solvent was removed in vacuo and the residue purified by column chromatography on silica gel, eluting with dichloromethane, to yield 6-bromo-1H,3H-naphtho[1,8-cd]pyran as a white solid.

Provenance & Evidence