K. Zelenin, O. E. Kuznetsova, V. V. Alekseev
Oct 1, 1992
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Journal
Chemistry of Heterocyclic Compounds
Abstract
The reactions of methyl- and phenylglyoxal with 2,4-disubstituted thiosemicarbazides and of diacetyl with 4-monosubstituted thiosemicarbazides gave monothiosemicarbazones which were converted in trifluoroacetic acid into previously unknown 5-amino-2-acyl-2,3-dihydro-1,3,4-thiadiazolium salts. Diacetyl monosemithiocarbazones are cyclized to 5-methylene-1,2,4-triazin-3-thiones which are also obtained in the reaction ofdiacetyl with 2,4-disubstituted thiosemicarbazides. In particular cases the monothiosemicarbazones are converted into the corresponding 5-alkoxy-1,2,4-triazin-3-thiones in the presence of alcohols. The 3-thio-1,2,4-triazinium cations are formed from the 5-methylene- and 5-alkoxy derivatives in trifluoroacetic acid.