Expeditious synthesis of phenanthridines through a Pd/MnO2-mediated C-H arylation/oxidative annulation cascade from aldehydes, aryl iodides and amino acids

The expeditious construction of phenanthridine scaffolds via a Pd/MnO2-mediated C-H arylation/oxidative annulation cascade involving aldehydes, aryl iodides and amino acids is disclosed. This reaction proceeds smoothly involving the formation of multiple chemical bonds with the tolerance of a wide range of functional groups. The control experiments suggest a radical mechanism for C-N bond formation via MnO2-promoted oxidative annulation of imine compounds. The synthetic utility of this transformation has been demonstrated via the straightforward access to bioactive natural alkaloid trisphaeridine and its analogue.