Regioselective synthesis of isoquino[1,2-b][3]benzazepines (homoprotoberberines) through 11-membered-ring stilbene lactams obtained by radical macrocyclization
G. Rodriguez et al., Regioselective synthesis of isoquino[1,2-b][3]benzazepines (homoprotoberberines) through 11-membered-ring stilbene lactams obtained by radical macrocyclization, J ORG CHEM, 64(13), 1999, pp. 4830-4833
Silylated 11-membered-ring stilbene lactams 3 (E and Z) were easily prepare
d by intramolecular addition of an aryl radical to a trimethylsilylacetylen
e. Oxidation of their hindered stilbene double bonds with dioxiranes gave o
xidative 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[l,2-b][3]benzaz
epines (homoprotoberberines).