Construction of 3-aryl-1,2,4-benzotriazines via unprecedented rearrangement of bis(benzotriazol-1-yl)methylarenes

3-Aryl-1,2,4-benzotriazines were formed unexpectedly by the treatment of 1,l-bis(benzotriazol-1-yl)methylarenes with allylsamarium bromide. A radical process was proposed involving steps, such as fragmentation, ring-opening, and cyclization.