Catalytic Asymmetric Syntheses of 2-Aryl Chromenes

Chiral chromene motifs are important heterocycles in numerous natural products and bioactive molecules. Among them, flavenes, flavanes, and flavanones, which consist of the 2-aryl-chromene skeleton are observed most frequently. As subgroups of flavonoids, they often occur in various plants and show many biological activities, such as antitumor, antioxidant, antibacterial, anti-inflammatory, and anticoagulant properties. This Minireview summarizes recent reports on catalytic asymmetric synthesis of flavenes, flavanes, and flavanones.