Electron-transfer-mediated synthesis of phenanthridines by intramolecular arylation of anions from n-(ortho-Halobenzyl)arylamines: regiochemical and mechanistic analysis

Abstract

The synthesis of a series of substituted phenanthridines by photostimulated C-C cyclization of anions from N-(orrAo-halobenzyl)arylamines has been found to proceed in very good to excellent yields (79-95%) in liquid ammonia and in DMSO. The N-(ortho-halobenzyl)arylamines are obtained in good to very good isolated yields (44-85%) by nucleophilic substitution of orthohalobenzylchlorides with different arylamines. The reaction of the anions of a diverse set N-(orthohalobenzyl)arylamines was studied, and the methodology was extended to the synthesis of trispheridine, a natural product, in very good yield, In order to explain the regiochemical outcome of these reactions, a theoretical analysis was performed with DFT methods and the B3LYP functional.