Recent advances in the diversification of chromones and flavones by direct CH bond activation or functionalization

Chromone and flavone are both central backbones of natural products and clinical medicines. Synthesis of diversely functionalized chromones and flavones constitutes significant research contents of the modern synthetic science because abundant molecular libraries of such types are crucial in providing candidate compounds for the discovery of new pharmaceuticals and functional materials. The direct CH bond activation or functionalization on these heterocyclic backbones provides highly powerful tools for the rapid accesses to densely functionalized chromone and flavone derivatives. Considering the importance of the functionalized chromone and flavone compounds as well as the notable advances in the synthesis of such products by direct CH activation or functionalization, we review herein the research advances in the CH bond activation and functionalization reactions of chromone and flavones, in hope of showing the current states and promise of the research domain.