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Cyclization of 1‐substituted‐3‐thiosemicarbazides to triazole derivatives under alkaline conditions
Author(s) -
Altland Henry W.,
Graham Patricia A.
Publication year - 1978
Publication title -
journal of heterocyclic chemistry
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.321
H-Index - 59
eISSN - 1943-5193
pISSN - 0022-152X
DOI - 10.1002/jhet.5570150305
Subject(s) - chemistry , alkyl , alcohol , alkoxy group , medicinal chemistry , hydrogen sulfide , organic chemistry , sulfur
Abstract Under both weakly and strongly alkaline conditions, 1‐alkyl‐2,5‐dithiobiureas (1‐alkyl‐thiocarbamoyl‐3‐thiosemicarbazides) form 4‐alkyl‐5‐amino‐1,2,4‐triazoline‐3‐thiones and 4‐alkyl‐1,2,4‐triazolidine‐3,5‐dithiones in varying proportions. 1‐Alkoxythiocarbonyl‐3‐thiosemicarbazides expel hydrogen sulfide under weakly basic conditions to form the corresponding 5‐alkoxy‐1,2,4‐triazoline‐3‐thiones. In a strongly alkaline environment, however, these alkoxy‐thiocarbonyl thiosemicarbazides eliminate alcohol to form the appropriate 1,2,4‐triazolidine‐3,5‐dithiones. 1‐Alkoxycarbonyl‐3‐thiosemicarbazides eliminate alcohol in both weakly and strongly basic media to give 5‐thiono‐1,2,4‐triazolidine‐3‐ones. Cyclization mechanisms of these thiosemicarbazides are postulated.