Stereoselective Syntheses of 3-Substituted Flavene Derivatives and Asymmetric Dehydration via Kinetic Resolution

摘要

The 2-phenyl-2H-chromene structural core is a widespread element in natural flavonoids and has attracted intense attention since a wide range of biological activities associated with the scaffold have been identified. Accordingly, the development of facile synthetic strategies to access such heterocycles is of considerable interest and a few asymmetric synthetic methods have been reported recently. Although the asymmetric methods could provide enantio-enriched flavene derivatives, their development for more functionalized flavene skeleton has proven to be a challenging synthetic task. In this communication, we wish to report diastereoselective Reformatsky reaction of flavene-3-carb-aldehydes to provide β-(2H-3-flavenyl)-β-hydroxy esters and disclose a new enantioselective synthetic method for 3-substituted flavene derivatives by asymmetric dehydration via kinetic resolution.