Denitrogenative cleavage of benzotriazoles and benzotriazinones, and selective N-desulfonylation of benzotriazoles by aluminum halides

• Benzotriazoles bearing a hydroxy or acyl group can be cleaved by AlI 3 . • 1-Sulfonylbenzotriazoles are chemoselectively desulfonylated by AlI 3 . • Cleavage of 3-alkylbenzotriazinones by AlI 3 affords 2-iodobenzamides. • Cleavage of 3-arylbenzotriazinones by AlI 3 provides 1-phenanthridinones. • AlCl 3 reacts with 1-acetylbenzotriazole and benzotriazinones differently. Regiospecific denitrogenative cleavage and chemoselective N -desulfonylation of benzotriazoles and benzotriazinones by aluminum halides are investigated. Products of these transformations are dependent on the N -substituents as well as the aluminum halides. For benzotriazoles bearing an N -hydroxy or acetyl substituent, denitrogenative cleavage occurs that affords 2′-iodoacetanilides as the products when carried out in the presence of AlI 3 and acetic anhydride. Analogous cleavage of benzotriazinones by AlI 3 furnishes 2-iodobenazmides or 1-phenanthridinones. In contrast, treatment of 1-acetylbenzotriazole and 1,2,3-benzotriazones with AlCl 3 provided benzotriazole and quinazolinones, respectively. 1-Sulfonylbenzotriazoles, to the contrary, prefer to undergo N -desulfonylation. AlI 3 is unreactive towards typical aromatic sulfonamides, making the deprotection of 1-sulfonylated benzotriazoles chemoselective.