[CH:1]1[CH:2]=[CH:3][C:4]([C@H:7]2[O:17][C:16]3[CH:15]=[C:14]([OH:18])[CH:13]=[C:12]([OH:19])[C:11]=3[C:9](=[O:10])[CH2:8]2)=[CH:5][CH:6]=1.Cl.O.CO>CN(C=O)C.[Pd]>[CH2:8]1[C:9](=[O:10])[C:11]2[C:16](=[CH:15][C:14]([OH:18])=[CH:13][C:12]=2[OH:19])[O:17][CH:7]1[C:4]1[CH:3]=[CH:2][CH:1]=[CH:6][CH:5]=14.4 g of the benzyl protected pinocembrin in R-configuration obtained in Example 3 was dissolved in 100 ml of DMF, 20 ml of 10% aqueous HCl and 3.5 g of 10% Pd—C with a water content of 62.9% were added, and then a hydrogenation at normal pressure was performed. The reaction was monitored by TLC until completion (about 5 h). Then stopped stirring, the reaction mixture was filtered and extracted with ethyl acetate and water. The organic phase was collected, evaporated to remove solvent, and recrystallized with 95% ethanol to give a white solid of (S)-pinocembrin (3.0 g, yield 92%) with specific rotation [α]D20=−45.63° (c=0.515, methanol), and e.e %>99.3%.
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