A Practical Access to Highly Enantiomerically Pure Flavanones by Catalytic Asymmetric Transfer Hydrogenation

摘要

Flavonoids constitute the largest share of secondary metabolites occurring in higher plants. A subgroup of these natural products, the flavanones (1), features a variety of useful bioactivities such as antifungal, antibacterial, and antiviral effects (Scheme 1). Particularly prenylated derivatives show pronounced physiological activities. The naturally occurring (25) enantiomer of 8-prenylnaringenin (3), also known as sophoraflavanon B, is currently the strongest phytoestrogen known and additionally exhibits further interesting biological properties. Similarly, the less oxygenated prenylated flavanone glabrol (4) displays a range of interesting biological effects. Amongst others the licorice constituent (S)-4 inhibits the cancer target isoprenylcysteine carboxyl methyl-transferase and shows potent activity against Staphylococcus aureus and Mycobacterium smegmatis.