ISSN:
1573-8353
Source:
Springer Online Journal Archives 1860-2000
Topics:
Chemistry and Pharmacology
Notes:
Abstract Dehydrobromination of N-arylhydrazones of bromonitroformaldehyde (at 20°C) in the presence of alkali and ammonium salts of strong mineral acids, HNO3, silica gel, and Al2O3 forms mesoionic 3-aryl-1,2,3,4-oxatriazol-5-ones (3-arylazasydnones). The effect of the electronic properties of the aryl substituent on the course of the reaction is evaluated. This evaluation is used to develop a general method for preparing 3-arylazasydnones with various substituents including novel 3-hetarylazasydnone derivatives of pyrazole, 1,2,4-triazole and pyridine. Aromatic electronic effects (σI, σR, σm, σp) of the mesionic 1,2,3,4-oxatriazol-5-on-3-yl moiety are determined by19F NMR. A scheme is proposed for the dehydrobromination of the bromonitroformaldehyde N-arylhydrazones that includes the intermediate N-aryl-C-(nitro) nitrilimines, ArN−−N=C+NO2, with subsequent isomerization of the latter into 3-arylazasydnones.
Type of Medium:
Electronic Resource
URL:
http://dx.doi.org/10.1007/BF02259369
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