Trifluoroacetic Acid-Mediated Denitrogenative -Hydroxylation of 1,2,3-Benzotriazin-4(3)-ones: A Metal-Free Approach.

An efficient trifluoroacetic acid-mediated denitrogenative hydroxylation of 1,2,3-benzotriazin-4(3)-ones is described. This metal-free approach is compatible with a wide range of 1,2,3-benzotriazin-4(3)-ones, affording -hydroxylated benzamides in good to high yields with a short reaction time. The reaction is believed to proceed via a benzene diazonium intermediate. The synthetic utility of the reaction was successfully demonstrated by the preparation of an antimicrobial drug, Riparin C, and benzoxazine-2,4(3)-diones in good yields.