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Arbeiten über Phosphorsäure‐ und Thiophosphorsäureester mit einem heterocyclischen Substituenten. 3. Mitteilung . Thiadiazol‐Ringschluss und eine dabei auftretende Methylübertragung
Author(s) -
Rüfenacht K.
Publication year - 1972
Publication title -
helvetica chimica acta
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.74
H-Index - 82
eISSN - 1522-2675
pISSN - 0018-019X
DOI - 10.1002/hlca.19720550414
Subject(s) - chemistry , transmethylation , carbon disulfide , medicinal chemistry , organic chemistry , biochemistry , amino acid , methionine
Methods for the synthesis of 5‐alkoxy‐ and 5‐alkylthio‐1,3,4‐thiadiazol‐ 2(3H) ‐ones and ‐thiones, known in principle, are extended and adapted for large scale preparations. In the particular case of 5‐methoxy‐1,3,4‐thiadiazol‐ 2(3H) ‐thione the cyclisation of thiocarbazic O‐methyl ester using alcoholic alkali and carbon disulfide added in this order surprisingly yields by transmethylation 5‐methylthio‐1,3,4‐thiadiazol‐ 2(3H) ‐one, isomer of the expected 5‐methoxy‐1,3,4‐thiadiazol‐ 2(3H) ‐thione. This latter compound is obtained when the reactants are applied in the inverse sequence. A possible mechanism for this behaviour is presented.