Rh(III)-Catalyzed Dual C-H Functionalization and C-O/C-N Annulations of Monoamide Fumarates.

Pyrano[4,3- c ]pyridine-diones, which are the key skeleton of bioactive compounds and functional materials, are usually prepared via a multistep synthesis using expensive substrates. This work demonstrates that Rh(III)-catalyzed dual C(sp 2 )-H functionalization and C-O/C-N annulation of monoamide fumarates can produce pyrano[4,3- c ]pyridine-1,5(6 H )-diones in high yield (up to 82%) in a single step. The substrates of monoamide fumarates and acetylenes are structurally simple, readily available, and inexpensive. The additive AgSbF 6 effectively raised the yields. On account of easier dehydrogenation of OH in the COOH group than NH in the amide group in the reaction, the process first undergoes C-O annulation and then is succeeded by C-N annulation.