Stereospecific 1,3-Aminobromination of Donor-Acceptor Cyclopropanes

Sn(OTf)(2)-catalyzed 1,3-aminobromination of donor-acceptor cyclopropanes with various sulfonyl amides or electron-poor anilines and N-bromosuccinimide is reported. These experimentally straightforward reactions occurred with complete regio- and stereospecificity (for anilines) to give gamma-aminated alpha-brominated malonic diesters in good to excellent yields (up to 98%). These compounds served as valuable substrates for subsequent reactions to provide substituted azetidines and gamma-lactams in high yields.