5-Methylene-10,11-dihydro-5H-dibenzo[a,d][7]annulene → 5-bromomethylene-10,11-dihydro-5H-dibenzo[a,d]cycloheptene

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Reaction Steps

Dissolve 5-methylene-10,11-dihydro-5H-dibenzo[a,d]cycloheptene (10.00 g, 48.48 mmol) in CHCl3 (125 mL) and add 4-(dimethylamino)pyridinium tribromide (19.35 g, 53.32 mmol). Stir at room temperature for 2.5 h and quench with saturated aqueous Na2SO3. Separate layers, wash organics with saturated aqueous NaHCO3, then H2O. The dried organics (MgSO4) and concentrated to a yellow oil. Purify crude product by loading onto a 20 g plug of silica gel and eluting with hexanes until eluent shows no UV activity. Combine and concentrate hexane washes to afford 13.01 g (94%) of the title compound as a white solid, mp 73.6° C. HPLC shows 99% purity.

Provenance & Evidence