Production of Chiral Aromatic Alcohol by Asymmetric Reduction with Vegetable Catalyst

Abstract

Chiral aromatic alcohols are the key chiral building block for many important enantiopure pharmaceuticals. In this work, we studied asymmetric reduction of prochiral aromatic ketone to produce the corresponding chiral alcohol using vegetables as the biocatalyst. Acetophenone was chosen as the model substrate. The results indicate that acetophenone can be reduced to the corresponding chiral alcohols with high enantioselectivity by the chosen vegetables, i. e. apple ( Malus pumila), carrot ( Daucus carota), cucumber ( Cucumis sativus), onion ( Allium cepa), potato ( Soanum tuberosum), radish ( Raphanus sativus), and sweet potato ( Ipomoea batatas). In the reaction, R-1-phenylethanol is produced with apple, sweet potato and potato as the catalyst, while S-1-phenylethanol is the product with the other vegetables as the catalyst. In term of the enantioselectivity and reaction yield, carrot ( D. carota) is the best catalyst for this reaction. Furthermore, the reaction characteristics were studied in detail using carrot ( D. carota) as the biocatalyst. The effects of various factors on the reaction were investigated and the optimal reaction conditions were determined. Under the optimal reaction conditions (reaction time 50 h, substrate concentration 20 mmol·L −1, reaction temperature 35 °C and pH 7), 95% of e. e. (to S-1-phenylethanol) and 85% chemical yield can be obtained. This work extends the biocatalyst for the asymmetric reduction reaction of prochiral aromatic ketones, and provides a novel potential route to produce enantiopure aromatic alcohols.