Selectfluor‐Mediated Synthesis of Fluoro Spiro 3(2H)‐Furanone Derivatives via Domino Fluorination–Defluorination

An unprecedented Domino transformation towards diverse fluorinated spiro benzothiazinyl furanone scaffolds has been developed from 1,3‐diketone embedded benzothiazines and Selectfluor through fluorinative intramolecular cyclization. The transformation is triggered by fluorine insertion to form a difluoro intermediate, which is responsible for the formation of fluorinated spiro 3(2H)‐furanone derivatives. We have also succeeded to synthesize non‐fluorinated spiro 3(2H)‐furanone derivatives by oxidative cyclization using AgF. A series of novel fluorinated spiro 3(2H)‐furanone derivatives were prepared from benzothiazines through Domino fluorinative intramolecular cyclization using Selectfluor under mild conditions. It involves fluorine insertion followed by spiroannulation. Non fluorinated spiro 3(2H)‐furanone derivatives also accomplished by AgF mediated oxidative cyclization.