Preparation of phenanthridines from N-(o-arylbenzyl)trifluoromethanesulfonamides with 1,3-diiodo-5,5-dimethylhydantoin

Abstract

Treatment of N -( o -arylbenzyl)trifluoromethanesulfonamides with 1,3-diiodo-5,5-dimethylhydantoin in 1,2-dichloroethane under irradiation with a tungsten lamp, followed by the reaction with t BuOK gave the corresponding 6-arylphenanthridines and 6-unsubstituted phenanthridines in good to moderate yields, respectively. The reaction proceeds through an oxidative cyclization onto the aromatic ring by sulfonamidyl radicals formed from the N -iodosulfonamides. The present reaction is a one-pot method for the preparation of both 6-arylphenanthridines and 6-unsubstituted phenanthridines from N -( o -arylbenzyl)trifluoromethanesulfonamides under transition-metal-free conditions. © 2020 Elsevier Science. All rights reserved. • One-pot multi-operation. • N(sp 2 )-C(sp 2 ) construction.