Access to Chromenopyrrolidines Enabled by Organophotocatalyzed [2 + 2 + 1] Annulation of Chromones with N -Arylglycines.

A facile approach toward chromenopyrrolidines was achieved under mild conditions via organophotocatalyzed aerobic decarboxylative [2 + 2 + 1] annulation of chromones with N -arylglycines, in which N -arylglycines perform dual roles (i.e., radical precursor and methylene provider). Mechanistic studies suggested that a Giese-type radical addition and consequent Mannich pathway were likely responsible for the annulation reaction.