Abstract
Fission of 1,2,4‐Thiadiazol‐3‐ones by Triphenylphosphane: gewidinet Triphenylphosphonio Thioimidazolates and Their Consecutive ReactionsTreatment of benzimidazo[1,2‐d][1,2,4]thiadiazol‐3(2H)‐ones (1) and imidazo[1,2‐d]‐[1,2,4]thiadiazol‐3(2H)‐ones (17) with triphenylphosphan leads to the liberation of isocyanate and the formation of triphenylphosphonio‐thiobenzimidazolat (4) and triphenylphosphonio‐thioimidazolat (18), respectively. 2,4‐Diphenyl‐5‐phenylimino‐1,2,4‐thiadiazol‐3‐one (23) is desulfurized with Ph3P and decomposed into phenyl isocyanate and diphenylcarbodiimide whereas the N‐unsubstituted imino‐thiadiazol‐3‐one (25) is attacked at the exocyclic imino group by Ph3P to give the N‐phosphoranylidene thiourea (26). The structure of 4 can be rationalized as a dynamic system between polar and apolar valence isomeres. Reactions of 1 and 17 with cyanates, isocyanates, carbon disulfide, acetic anhydride, amines, benzyl chloride, grignard compounds, and CH acidic compounds are described.
Published Version
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