Alexander E. Frumkin, Alexander D. Dilman
An approach for the selective synthesis of benzo[ e ][1,2,4]triazines from readily accessible azooximes is described. The method is based on cyclocondensation reaction performed at room temperature in the presence of trifluoroacetic anhydride and methanesulfonic acid. The process leads to specifically substituted benzo[ e ][1,2,4]triazines, which can serve as precursors of stable Blatter radicals. The method features inexpensive and readily available starting materials, broad substrate scope, mild and metal‐free reaction conditions, and versatile functionalization of the 1,2,4‐benzotriazines.