[Br:1][C:2]1[CH:3]=[CH:4][C:5]([OH:17])=[C:6]([CH:16]=1)[C:7]([C:9]1[CH:14]=[CH:13][C:12]([CH3:15])=[CH:11][CH:10]=1)=[O:8].N1C=CC=CC=1.[C:24](Cl)(=[O:26])[CH3:25].Cl>ClCCl>[C:24]([O:17][C:5]1[CH:4]=[CH:3][C:2]([Br:1])=[CH:16][C:6]=1[C:7]([C:9]1[CH:14]=[CH:13][C:12]([CH3:15])=[CH:11][CH:10]=1)=[O:8])(=[O:26])[CH3:25]To a yellow solution of 229 mg (0.8 mmol) of 5-bromo-2-hydroxy-4'-methylbenzophenone (Compound K) in 15 mL of dichloromethane (under a blanket of argon) was added 0.07 mL (69 mg, 0.9 mmol) of pyridine followed by 0.07 mL (74 mg, 0.9 mmol) of acetyl chloride. The resultant reaction mixture was stirred at ambient temperature overnight (16.75 hours), poured into 10% HCl (aq.) solution and extracted with ethyl acetate. The layers were separated and the aqueous phase was washed with ethyl acetate. The organic phases were combined and then sequentially washed with sat. NaHCO3 (aq.) solution, water and brine, dried over MgSO4, filtered and concentrated in vacuo to give a yellow oil. Purification by flash chromatography (silica, 20% ethyl acetate in hexane) gave the title compound as a clear, colorless oil.
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