Copper(II)‐Catalyzed [2+2+2] Annulation of Enaminones with Maleimides Using a Traceless Directing Group Strategy

A copper‐catalyzed annulation of enaminones with maleimides was developed to synthesize various pyrrolo[3,4‐e] isoindoles. In this strategy, 2‐aminopyridine served as a traceless directing group, and target products were obtained in 54‐72% yields. Moreover, a plausible mechanism for this reaction was proposed based on several control experiments, deuterium exchange experiments, and previous reports.