Catalytic methods to introduce fluorine into the backbone of small-ring heterocycles are challenging due to the problems of strain-induced ring cleavage and defluorination. Now, a copper catalyst mediates insertion of an in situ-generated difluorocarbene into oxygen heterocycles, affording ring-expanded fluorinated pharmacophores. Experimental and computational studies provide insights into the mechanism.
- Tong-De Tan
- Fang Zhou
- Ming Joo Koh
