Synthesis of Difluoromethylated and Phosphorated Spiro[5.5]trienones via Dearomative Spirocyclization of Biaryl Ynones.

Copper- or silver-catalyzed cascade radical addition/dearomative spirocyclization of biaryl ynones with fluoroalkyl bromides or diethylphosphite has been realized for the first time. This method provides a novel and step-economical protocol for the divergent synthesis of a wide range of difluoromethylated or monofluoromethylated and phosphorated spiro[5.5]trienones in moderate to high yields.