Synthetic study of perophoramidine: Construction of pentacyclic core structure via SmI2-mediated reductive cyclization

Article abstract of DOI:10.1016/j.tet.2013.04.039

An intramolecular SmI₂-mediated reductive cyclization of carbodiimides and unsaturated lactams was applied to functionalized substrates bearing tetrasubstituted olefins. The reaction afforded arylated spiro-2-iminoindolines in high yield. Although the stereochemistry of the product was different from the desired one, the optimized palladium-catalyzed aryl amidination realized the isomerization and C-N bond formation in a single step and resulted in efficient construction of pentacyclic core of perophoramidine synthetically equivalent to the Rainier's intermediate.