Ruthenium‐Catalyzed Double C(sp2)−H Functionalizations of Fumaramides with Alkynes for the Divergent Synthesis of Pyridones and Naphthyridinediones

Transition‐metal‐catalyzed C−H functionalization of aromatic secondary amides with alkynes mainly undergo C−H/N−H annulation but rarely undergo ortho‐alkenylation. It is particularly challenging to selectively realize both oxidative annulation and ortho‐alkenylation of aromatic secondary amides with alkynes in the transition‐metal‐catalysis. In this article, we synthesized fully‐substituted 2‐pyridones and 2,6‐naphthyridine‐1,5‐diones via C(sp2)−H functionalization of fumaramides for the first time. Under the Ru‐catalysis, fumaramides and 1,2‐diaryl ethynes first undergo C−H/N−H annulation leading to the intermediate 2‐pyridone with an exocyclic secondary amide, and subsequently undergo the unexpected stereoselective C−H alkenylation to realize fully substituted 2‐pyridones bearing an exocyclic anti alkenyl group. On the addition of K2CO3, however, the transformation of fumaramides with 1,2‐dialkyl ethyne undergoes two conventional C−H/N−H annulations to provide 2,6‐naphthyridine‐1,5‐diones in high yield. The two procedures can be successfully enlarged to gram‐scales without erosion of the yields. In addition, some 2‐pyridones and 2,6‐naphthyridine‐1,5‐diones emitting clear ultraviolent and fluorescent light, indicating the potential utility of this work in organic light‐emitting materials. It's ring time: Transition‐metal‐catalyzed C−H functionalization of aromatic secondary amides with alkynes rarely undergo ortho‐alkenylation. Here we can show that fumaramides can be transferred into highly‐substituted 2‐pyridones or 2,6‐naphthyridine‐1,5‐diones, respectively.