50289-86-6Relevant academic research and scientific papers
Ring Contraction of 1,2,4-Benzoxadiazines to Benzoxazoles
Gilchrist, Thomas L.,Harris, C. John,King, Frank D.,Peek, Michael E.,Rees, Charles W.
, p. 2169 - 2174 (2007/10/02)
1,2,4-Benzoxadiazines (1) undergo a ring contraction to benzoxazoles (2) on heating.Other products of the reaction have been identified as nitrogen and ammonia.A mechanism is suggested for this reaction which involves (i) electrocyclic ring opening to an o-benzoquinone imine, (ii) recyclisation to a diaziridine, and (iii) extrusion of a nitrene fragment.Evidence is presented which is consistent with this proposal: thus, the benzoxazole (7) is produced on heating 3,5-di-t-butyl-o-benzoquinone with benzamidine and 4-nitrobenzoylnitrene is intercepted as the ylide (11) from the thermolysis of the substituted benzoxadiazine (10).
