C3‐Functionalized Chromones Synthesis by Tandem C−H Elaboration and Chromone Annulation of Enaminones

Abstract Chromone is a heterocyclic entity presents in a number of natural products, clinical pharmaceuticals, as well as molecules with enriched biological functions. As cutting‐edge area, the synthesis of chromones has seen spectacular progress over the past decade. Among the available synthetic modes toward chromone scaffolds, the annulation of ortho ‐hydroxyphenyl functionalized N,N ‐disubstituted enaminones has turned out to be one of the most reliable and practical ones. By combining this annulation with the featured transformation of the vinyl α‐C−H bond in the enaminone structure, a large number of tandem reactions providing structurally diverse chromones with C3‐functionalization have been recently realized. As a practical strategy in the synthesis of valuable heterocyclic molecules and an important branch in the enaminone‐based organic synthesis, such synthetic reactions are highly instructive for organic chemistry and many other disciplines related to this heterocyclic moiety. Herein, we present for the first time the research advances on the synthesis of C3‐functionalized chromones via tandem vinyl C−H bond elaboration and chromone annulation of ortho ‐hydroxyphenyl functionalized tertiary enaminones.