58758-38-6Relevant academic research and scientific papers
Access to C4-arylated benzoxazoles from 2-amidophenol through C-H activation
Panda, Niranjan,Pradhan, Priyanka,Sahoo, Kanchanbala
, p. 1820 - 1832 (2020/03/17)
A Pd-catalyzed aerobic approach to access C4-aryl benzoxazoles by tandem C-H ortho-arylation and acid-mediated annulation of 2-amidophenol has been presented. The directing potential of the -NHCOR group over the -OH group was exploited for selective arylation adjacent to the amide group. Deuterium labeling experiments suggest that palladation predominantly occurs adjacent to the -NHCOR group and is the key step during benzoxazole formation. One-pot hydrolysis of the resulting C4-arylated benzoxazole was also accomplished to access structurally challenging 3-aryl aminophenols for further applications.
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).
