A summary of seven- and eight-membered ring sultam syntheses via three Michael addition reactions
From one starting material, two tandem reaction protocols to synthesize seven- and eight-membered ring sultams were developed. One protocol employs intermolecular epoxide ring-opening by NaN3, followed by an intramolecular 7-endo-trig oxa-Michael addition reaction. The second protocol applies to intermolecular aza-Michael addition of a primary amine, followed by 8-endo-tet intramolecular epoxide ring-opening of the resultant amine intermediate. Both protocols afforded the respective sultams in good yields under mild reaction conditions.