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New routes to aroylthiadiazolines and arylazothiazoles from phenylglyoxalyl bromide arylhydrazones and phenacyl thiocyanate
Author(s) -
Shawali A. Sami,
Abdelhamid A. Osman
Publication year - 1976
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.5570130108
Subject(s) - chemistry , thiourea , phenacyl bromide , benzoyl chloride , potassium thiocyanate , medicinal chemistry , acetic anhydride , bromide , thiocyanate , pyridine , phenacyl , nitrosation , iodide , hydroxylamine , chlorobenzene , phenylhydrazine , ethanol , organic chemistry , catalysis
Reaction of phenylglyoxalyl bromide arylhydrazones (III) with thiourea in ethanol produces 2‐amino‐4‐phenyl‐5‐arylazothiazoles (XI) instead of the expected 2‐benzoyl‐4‐aryl‐5‐imino‐Δ 2− 1,3,4‐thiadiazolines (V) obtained from III and potassium thiocyanate. Phenacyl thiocyanate (IV) couples with diazotized anilines to give V. The mechanisms of formation of V and XI from VI and III, respectively, are postulated. Nitrosation of V gives the corresponding N ‐nitroso derivatives (VII), which decompose upon refluxing in xylene to give 2,4‐disubstituted Δ 2 −1,3,4‐thiadiazolin‐5‐ones (VIII). The thiadiazolines V give the respective N ‐aeyl derivatives IX and X with acetic anhydride and benzoyl chloride in pyridine.