Accessing 7,8-Dihydroquinoline-2,5-diones via Rh-Catalyzed Olefinic C-H Activation/[4+2] Cyclization.

ABSTRACT

Herein, we report a rhodium-catalyzed C-H activation/[4+2] cyclization reaction between α,ß-unsaturated amides and iodonium ylides for the synthesis of novel 7,8-dihydroquinoline-2,5-diones and analogues. This protocol provides a series of pyridones fused with saturated cycles with good functional group compatibility, good water and air tolerance, and good to excellent yields under mild and green reaction conditions. Additionally, scale-up synthesis can be smoothly performed with as low as 0.25 mol % catalyst loading. Recycling experiments and different transformation experiments were also carried out to demonstrate the potential synthetic utility of this protocol.