Diversity-Oriented Synthesis of Flavones and Isoflavones via Palladium/Norbornene Cooperative Catalysis

Comprehensive Summary Flavones and isoflavones are recognized as privileged heterocyclic scaffolds for the preparation of bioactive compounds. Efficient methods to access these heterocycles are in urgent need. Herein, we report diversity-oriented synthesis of flavones and isoflavones from 3-iodochromones via palladium/norbornene cooperative catalysis. The success of this research relies on the use of a unique bridge-head ester modified norbornene derivative as the mediator. Salient features of this include readily available starting materials regarding 3-iodochromones, ortho-C-H arylating and alkylating reagents and ipso-terminating reagents, broad substrate scope, good chemoselectivity, good step-economy and scalability. A large number of structurally diversified flavones, isoflavones and 2,3-diarylated chromones can be quickly prepared in a predictable manner. As showcased by the efficient formal synthesis of umbralisib, this chemistry can be treated as another valuable addition to the toolbox of medicinal chemists.