The flavanone structure is a tough act to swallow, synthetically speaking. Its the common skeleton for flavonoids and other compounds in plant-derived food and drink, such as red wine, dark chocolate, green tea, soy, milk thistle, kosam root, and citrus fruits, and are thought to have positive effects on health via anti-tumor and anti-inflammatory behavior. There are literally hundreds scattered throughout nature, but until now chemists had no straightforward method of synthesizing them with enantiomeric purity.
Karl Scheidt of Northwestern University and his colleagues have developed a general route to ten different chiral flavanones and chromanones that relies on simple bifunctional thiourea catalysts. The team reports how decarboxylation of the beta-ketoester proceeds smoothly in a one-pot reaction with 80-94% enantiomeric excess for aryl and alkyl substrates.
The method sets the stage for a new range of potential anticancer drugs ripe for testing. Further details can be found in JACS.