Synthesis of 6-Fluoroalkyl 6 H-Benzo[ c]chromenes via Visible-Light-Promoted Radical Addition/Cyclization of Biaryl Vinyl Ethers.

A novel visible-light-promoted cascade cyclization reaction for the synthesis of 6-fluoroalkyl 6 H-benzo[ c]chromenes has been successfully realized, which was initiated by intermolecular radical addition to biaryl vinyl ethers using easily available fluoroalkylated reagents BrCF2 CO2 Et or 2-bromo-2,2-difluoroamides as the sources of fluorinated radicals, followed by the cyclization onto an aromatic ring process. This protocol tolerated a wide range of functional groups and provided the desired products in moderate to good yields.