120914-33-2Relevant academic research and scientific papers
Synthesis and Thermal Reactions of 1,2-Dihydro-1,2,4-benzotriazines
King, Frank D.
, p. 3381 - 3386 (2007/10/02)
The 1,2-dimethyl-1,2,4-benzotriazines (7),(8), and (9) were prepared by acid-catalysed cyclisation of the 2-aminophenylhydrazine derivatives derived from (12), (13), and (14) respectively.Compounds (7) and(9) undergo a thermal elimination to fully aromatic benzotriazines.However, the 2-acyl derivative (18) rearranges to the thermodynamically more stable 4-acyl compound (21).In the presence of traces of water, a ring contraction to benzimidazoles is a competing reaction.For (18) the nitrogen fragment is retained in the benzamide (22).A mechanism for the ring contraction has been suggested in which initial hydration of the imine bond gives 1,2,3,4-tetrahydrobenzotriazines which ring-open, then re-cyclise to benzimidazoles.The benzimidazophthalazine (23) was shown not to be an intermediate in the water-mediated ring contraction of (18).
