Diastereoselective Synthesis of CF3‐Pyrano[3,4‐c]quinolones from Hetero‐Dendralenes and Aldehydes.

Herein, we demonstrate an Oxa‐Diels‐Alder reaction of 3‐trifluoroacetyl‐4‐methyl‐quinolin‐2(1H)‐one with aldehydes in the presence of a base to engineer the functionalized pyrano[3,4‐c]quinolones. This reaction proceeds through an in‐situ generated hetero dendralene intermediate and features perfect stereoselectivity on a wide range of substrates with excellent atom economy. The high electron‐withdrawing nature of CF3‐group is responsible for making the methyl group present in quinolone moiety more acidic to furnish the corresponding hetero dendralene intermediate. [ABSTRACT FROM AUTHOR]