Novel applications of hypervalent iodine: PIFA mediated synthesis of benzo[c]phenanthiridines benzo[c]phenanthridinones

A short and efficient access to benzo[c]phenanthridines and phenanthridinon es is achieved by the action of phenyliodine(m)-bis(trifluoroacetate) (PIFA ) on properly substituted benzylnaphthylamines and naphthylbenzamides, resp ectively. This reagent promotes a non-phenolic oxidative biaryl coupling pr ocess, the key step of the synthesis. A study of the electronic and steric requirements of the substrates is carried out since, in some cases, dimeriz ation processes prevail over intramolecular cyclization. A mechanistic prop osal is also included. (C) 2001 Elsevier Science Ltd. All rights reserved.