Synthesis of Dihydrophenanthridines and Oxoimidazolidines from Anilines and Ethylglyoxylate via Aza Diels–Alder Reaction of Arynes and KF-Induced Annulation

The transition-metal-free multicomponent coupling of arynes, anilines, and ethylglyoxylate, proceeding via an inverse electron-demand aza Diels–Alder cycloaddition and N-arylation, has been demonstrated. This protocol allows rapid access to N-aryl dihydro­phenanthridine derivatives in moderate to high yields at room temperature from readily available starting materials. In addition, an unprecedented fluoride induced annulation of ethyl­(arylimino)­acetates led to the formation of highly functionalized oxoimidazolidine derivatives in good yields under mild conditions.