Assembly of substituted phenanthridines via a cascade palladium-catalyzed coupling reaction, deprotection and intramolecular cyclization

The discovery and development of a general method for the one-pot synthesis of substituted phenanthridines is presented. In the presence of Pd(PPh3)(4), accessible precursors undergo a Suzuki cross-coupling reaction with 2-(Boc-amino)benzeneboronic acid pinacol ester and then spontaneously undergo deprotection and intramolecular condensation to form the corresponding phenanthridines in one step. This reaction has a wide range of substrates with various functional groups, and the corresponding products have been obtained in good yields.