Tandem metal-free oxidative radical 5-exo dearomative spirocyclization and ester migration: generation of 3-functionalized coumarins from alkynoates

A tandem metal-free oxidative radical cyclization of alkynoates is described to synthesize 3-functionalized coumarins. In the process, it is believed that radical addition of alkynoates, oxidative 5-exo dearomative spirocyclization and ester migration is proposed.