Ceric Ammonium Nitrate‐Promoted C4‐Selective Geminal Dinitration of Tetrahydroacridines and Nef‐Type Conversion to 2,3‐Dihydroacridin‐4(1 H )‐Ones

A catalyst‐free, ceric ammonium nitrate (CAN, (NH 4 ) 2 [Ce(NO 3 ) 6 ])‐promoted, C4‐selective gem ‐dinitration of 1,2,3,4‐tetrahydroacridines has been developed via benzylic C(sp 3 )–H functionalization. Acting as both an oxidant and a nitrating reagent, CAN enables the regioselective synthesis of 4,4‐dinitrated tetrahydroacridines in moderate‐to‐good yields with broad functional group tolerance. The resulting gem ‐dinitro products undergo an efficient DBU‐mediated Nef‐type transformation to furnish 2,3‐dihydroacridin‐4(1 H )‐ones. Mechanistic investigations, including radical trapping and intermediate isolation experiments, support a sequential radical‐mediated gem ‐dinitration pathway and identify a vinyl nitro intermediate in the subsequent Nef‐type transformation. To the best of our knowledge, this study represents the first example of a Nef‐type conversion of gem ‐dinitro compounds into 2,3‐dihydroacridin‐4(1 H )‐ones.