[CH:1]1([C:6]([C:8]2[CH:13]=[C:12]([O:14]C)[CH:11]=[C:10]([O:16]C)[CH:9]=2)=[O:7])[CH2:5][CH2:4][CH2:3][CH2:2]1.B(Br)(Br)Br>ClCCl.C(=O)=O.CC(C)=O>[CH:1]1([C:6]([C:8]2[CH:9]=[C:10]([OH:16])[CH:11]=[C:12]([OH:14])[CH:13]=2)=[O:7])[CH2:2][CH2:3][CH2:4][CH2:5]1To a solution of cyclopentyl-(3,5-dimethoxy-phenyl)-methanone (234 mg) in anhydrous dichloromethane (5 mL) cooled in dry ice/acetone bath was added dropwise a solution of boron tribromide (4 mL of 1 M solution in dichloromethane). After the addition was completed, the cooling bath was removed and the reaction mixture was stirred at room temperature overnight. Unreacted boron tribromide was quenched with methanol. Then the reaction mixture was diluted with ethyl acetate and washed with water and brine. The organic extract was dried over anhydrous sodium sulfate, concentrated and purified on a silica gel column using ethyl acetate and hexanes to yield 200 mg of the title compound (97% yield). Note: the title compound decomposes on air. HRMS calcd for C12H14O3 [M+H]+ 207.1016, observed 207.1016.
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