Copper(I)-Catalyzed Nitrosylation/Annulation Cascade of Enaminones with -Butyl Nitrite: Access to 1-1,2,3-Triazole 2-Oxides.

The direct synthesis of triazole 2-oxides has posed a challenge in the field of -heterocyclic chemistry. A novel copper(I)-catalyzed nitrosylation/annulation cascade of enaminones provides a straightforward route to 1-1,2,3-triazole 2-oxides by forming new C-N, N=N, and N-N bonds using noncorrosive -butyl nitrite (TBN) as both the N and NO sources. The synthetic protocol features easily accessible starting materials, wide substrate scopes, and good tolerance toward various functional groups while avoiding use of explosive azides.