B(O)(O)O.[CH3:5][O:6][C:7]1[CH:8]=[C:9]([C:15](=[O:31])[CH:16]([C:21]2[CH:26]=[CH:25][C:24]([O:27][CH:28]([CH3:30])[CH3:29])=[CH:23][CH:22]=2)C(OC)=O)[CH:10]=[C:11]([O:13][CH3:14])[CH:12]=1.C1(C)C=CC=CC=1>O>[CH3:5][O:6][C:7]1[CH:8]=[C:9]([C:15](=[O:31])[CH2:16][C:21]2[CH:22]=[CH:23][C:24]([O:27][CH:28]([CH3:29])[CH3:30])=[CH:25][CH:26]=2)[CH:10]=[C:11]([O:13][CH3:14])[CH:12]=19.65 g of boric acid (0.16 mol) and 58 g of crude methyl 3-(3,5-dimethoxyphenyl)-2-(4-isopropyloxyphenyl)-3-oxopropionate (0.16 mol) prepared according to Example 25 are introduced into a round-bottomed flask. The mixture is heated with stirring at 150-155° C. for 3 h and then cooled to approximately 80° C. 200 ml of toluene and then 150 ml of water are added. Separation by settling is carried out and the organic phase is recovered. The aqueous phase is re-extracted with 20 ml of toluene. The organic phases are concentrated to recover 48.8 g of crude 1-(3,5-dimethoxyphenyl)-2-(4-isopropyloxyphenyl)ethanone in the form of a viscous oil with a dark brown color.
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