Syntheses of 4-(5-oxo-1,2,4-triazol-3-yl)-sydnones and 4(4-arylamino-5-oxo-1,2,4-triazol-3-yl)-sydnones from sydnone derivatives and their fragments

Article abstract of DOI:10.1002/jccs.200000027

4-(5-oxo-1,2,4-triazol-3-yl)-sydnones 11 and 4-(4-arylamino-5-oxo-1,2,4-triazol-3-yl)-sydnones 13 have been obtained from a-chloroformylarylhydrazine hydrochloride 2. Moreover, the intermediates, including 3, 4, 9 and 10, in this study are synthetically informative and valuable. It is also noteworthy that three reactants, 1, 2 and sydnonecarbaldehydes, were prepared from sydnone derivatives and their fragments. The oxidative cyclizations of sydnonecarbaldehyde semicarbazones 9 and carbazpnes 10 with two different oxidizing agents (Cu(ClO₄)₂ and Fe(ClO₄)₃) have been extensively examined. The reaction time and the yields of cyclizations were affected by the substituents of semicarbazones 9 and carbazones 10.