Regioselective synthesis of isoquino[1,2-b][3]benzazepines (homoprotoberberines) through 11-membered-ring stilbene lactams obtained by radical macrocyclization

Article abstract of DOI:10.1021/jo9901900

Silylated 11-membered-ring stilbene lactams 3 (E and Z) were easily prepared by intramolecular addition of an aryl radical to a trimethylsilylacetylene. Oxidation of their hindered stilbene double bonds with dioxiranes gave oxidative cleavage of their electron-rich aromatic rings. However, reduction of the amide to an amine functionality in both lactams (E and Z) triggers a regioselective [7,6]-transannular cyclization to isoquino[1,2-b][3]benzazepines (homoprotoberberines).