Hydrochloric Acid → 5,7-Dihydroxyflavanone

Participants

Reaction Steps

4.4 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%.

Provenance & Evidence