Regioselective Nitrative Cyclization of 1,6-Enynes with t-BuONO under Metal-Free Conditions

A new pattern for nitrative cyclization of 1,6-enynes with t-BuONO has been reported for the synthesis of various 2-pyrrolidinone derivatives in 45-88% yields. This novel method is operationally simple and proceeds under very mild conditions without using any additives. The reaction pathway involves nitro radical addition toward an alkenyl group/5-exo-cyclization/H-abstraction sequence, allowing a highly regioselective and practical protocol toward the formation of new C-N and C-C bonds.