[OH:1][C:2]1[CH:7]=[C:6]([OH:8])[CH:5]=[CH:4][C:3]=1[C:9](=[O:19])[CH2:10][C:11]1[CH:16]=[CH:15][CH:14]=[CH:13][C:12]=1[O:17][CH3:18].[C:20]1(C)C=C(C)C=C(C)C=1Cl>CN(C=O)C>[OH:8][C:6]1[CH:7]=[C:2]2[C:3]([C:9](=[O:19])[C:10]([C:11]3[CH:16]=[CH:15][CH:14]=[CH:13][C:12]=3[O:17][CH3:18])=[CH:20][O:1]2)=[CH:4][CH:5]=1BF3—OEt2 complex (14 ml, 112 mmol) was gradually added to a solution of 1-(2,4-dihydroxy-phenyl)-2-(2-methoxy-phenyl)-ethanone (7.2 gm, 28 mmol) in DMF at 0° C. The resulting solution was stirred for 30 min. Mesityl chloride (6.5 ml, 84 mmol) was then gradually added to it at 50° C. The solution was then heated up to 110° C. for 5 hours. The mixture was then concentrated. The residue was treated with ice and the solid obtained was purified with silica gel column chromatography using hexane-chloroform as the eluent to give 7-hydroxy-3-(2-methoxy-phenyl)-chromen-4-one (5.6 gm, 75%) as white solid.
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