Reactions with 2‐thiazolin‐5‐ones. III. The behaviour of 4‐Arylazo‐2‐alkoxy‐2‐thiazolin‐5‐ones toward amines and Grignard reagents

Abstract

AbstractTreatment of 4‐arylazo‐2‐alkoxy‐2‐thiazolin‐5‐ones 4a–f with glycine or phenylhydrazine effects their conversion into 1‐aryl‐5‐alkoxy‐1 H‐1,2,4‐triazole‐3‐carboxylic acid derivatives 5a–j, with the loss of hydrogen sulfide. On the other hand, the reaction of the 2‐ethoxy (4a–c) and the 2‐isopropyloxy (4g–i) derivatives with strong basic amines involves the loss of an alkyl mercaptan to yield the N‐substituted amines 7d–j of 1‐aryl‐Δ2‐1,2,4‐triazolin‐5‐one‐3‐carboxylic acids. The 2‐benzyloxy derivatives 4d–f react with the same reagents to give the N‐substituted amides 2a–g of 1‐aryl‐Δ2‐1,2,4‐triazolin‐5‐thione‐3‐carboxylic acids, with the loss of benzyl alcohol.Hetero‐ring opening of 4, followed by recyclisation, occurs upon treatment with ethyl or phenyl magnesium halides to yield the triazolinethione derivatives 13 a–c.