Chiral Phosphoric Acid-Catalyzed Asymmetric 4 + 2 Cycloadditions of Photogenerated o -Quinodimethanes with Vinylazaarenes

Chiral cyclohexyl-appended azaarenes are highly sought synthetic targets in biochemistry and medicinal chemistry. Herein we report a chiral phosphoric acid-catalyzed asymmetric 4 + 2 cycloaddition reaction between photogenerated o-quinodimethanes and alkenylazaarenes. A wide range of cyclohexyl-appended azaarenes are obtained in moderate to high yields (up to 85%) with high diastereoselectivities (up to 20:1 dr) and excellent enantioselectivities (up to 98% ee). A scale-up experiment and derivatizations of products demonstrate the practical utility of this synthetic method.