Tetrazole derivatives. 25. Investigation of the synthesis of 1-(5-tetrazolyl)-3,5-diphenylleucoverdazyl. Structure and some properties of the accompanying product - 1,3,7,9-tetraphenyl-5-oxo-5H-1,2,4-triazolo[3′,4′:5,1]imidazo[4,3-c] -1,2,4-triazole

Article abstract of DOI:10.1007/BF00505702

In the reaction of 1,3-diphenyl-5-(5-tetrazolyl)formazan with formaldehyde, in addition to a leucoverdazyl, one can obtain 1,3-diphenyl-1,2,4-triazole and 1,3,7,9-tetraphenyl-5-oxo-5H-1,2,4-triazolo[3′,4′:5,1]imidazo[4,3-c]-1,2,4-triazole. The structure of the latter was established from data from the mass spectrum and the ¹H and ¹³C NMR, UV, and IR spectra, as well as from the products of alcoholysis of this compound, which leads to 1,3-diphenyl-1,2,4-triazole and 1,3-diphenyl-5-carbethoxy-1,2,4-triazole. According to the data from the PMR spectra, the leucoverdazyl displays prototropic tautomerism due to the NH proton of the tetrazine ring.