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Tautomerism and Alkylation of 5-Amino-2H-1,2,4-thiadiazoline-3-one
Tautomerism and Alkylation of 5-Amino-2H-1,2,4-thiadiazoline-3-one
Journal of the Korean Chemical Society. 1995. Jul, 39(7): 564-571
  • Published : July 00, 1995
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Cho, Nam Sook
Park, Young Cheol
Ra, Do Young
Kang, Sungkwon

Abstract
5-Amino-2H-1,2,4-thiadiazoline-3-one has been prepared from 2-thiobiuret through a oxidative cyclization under basic hydrogen peroxide condition. Lactam-lactim tautomerism of 5-amino-2H-1,2,4-thiadiazoline-3-one has been examined by spectroscopic methods and ab initio molecular orbital calculation. These results were shown that 5-amino-2H-1,2,4-thiadiazoline-3-one exists as lactam form. Reaction conditions for alkylating 5-amino-2H-1,2,4-thiadiazoline-3-one with alkyl halides in the presence of various bases were studied in DMF and $H_2O$-THF two phase system. $Li_2CO_3$ base in DMF method gave best result in this investigation. The alkylation has been taken place at N-2 position. The identification of the product is confirmed by spectral data of IR, $^1H$ NMR and $^13C$ NMR and the comparison of authentic sample, 5-amino-2-methyl-1,2,4-thiadiazolidine-3-one, obtained from the oxidative cyclization of 5-methyl-2-thiobiuret.