Bromine → 1-bromo-3a-ethyl-7-methoxy-3,3a,4,5-tetrahydro-2H-cyclopenta[a]naphthalen-2-one

Participants

Reaction Steps

A solution of 3a-ethyl-7-methoxy-3,3a,4,5-tetrahydro-2H-cyclopenta[a]naphthalen-2-one (415 mg, 1.7 mol) in CCL4 (5.1 mL) was treated with NaHCO3 (714 mg, 8.5 mmol). The mixture was cooled in an ice bath, purged with N2, stirred, and treated with Br2 (0.088 mL, 1.7 mmol) to give an unstirrable orange gum. The mixture was sonicated for one minute, swirled in an ice bath for two minutes, and then stirred at 0-5° C. for 75 minutes. The mixture was then partitioned between CH2Cl2 and water (50 mL each). The organic phase was washed with saturated aqueous Na2S2O3 and brine, dried over MgSO4, filtered, and evaporated under vacuum. The crude product was purified by Biotage™ (Charlottesville, Va.) flash chromatography on a 40M (4×15 cm) silica gel column, eluting with 5:1 hexane-EtOAc, to provide 1-bromo-3a-ethyl-7-methoxy-3,3a,4,5-tetrahydro-2H-cyclopenta[a]naphthalen-2-one as a white foam.

Provenance & Evidence