One‐Pot Synthesis of Fused N,O‐Heterocycles through Rh(III)‐Catalyzed Cascade Reactions of Aromatic/Vinylic N‐Alkoxy‐ Amides with 4‐Hydroxy‐2‐Alkynoates

Abstract

AbstractA highly efficient and regioselective synthesis of furo[3,4‐c]isoquinoline‐1,5(3H,4H)‐diones and furo[3,4‐b]pyridine‐2,5(1H,7H)‐diones via Rh(III)‐catalyzed one‐pot cascade reactions of aromatic/vinylic N‐alkoxyamides with 4‐hydroxy‐2‐alkynoates is presented. Mechanistically, the formation of the title compounds is triggered by a Rh(III)‐catalyzed inert C(sp2)−H bond activation of the amide substrate followed by its [4+2] annulation and lactonization with 4‐hydroxy‐2‐alkynoate featuring with an oxidizing and partially traceless directing group. To the best of our knowledge, this is the first example in which both the furan‐2(5H)‐one and the pyridin‐2(1H)‐one scaffolds are constructed in one pot under one set of reaction conditions. Compared with literature methods, notable features of this new protocol include facile formation of bis‐heterocyclic scaffolds from readily available acyclic substrates, broad substrate scope with good tolerance of a wide range of functional groups, excellent regioselectivity and high efficiency.magnified image