Acylation of 5-amino-3H-1,3,4-thiadiazolin-2-one

✍ Scribed by Do Young Ra; Nam Sook Cho; Jae Joo Cho

• Publisher: Journal of Heterocyclic Chemistry
• Year: 1998
• Tongue: English
• Weight: 364 KB
• Volume: 35
• Category: Article
• ISSN: 0022-152X
• DOI: 10.1002/jhet.5570350306

✦ Synopsis

Abstract

Acylation of 5‐amino‐3__H__‐1,3,4‐thiadiazolin‐2‐one (2) was undertaken selectively at either the 3‐NH position or at 5‐amino group depending on reaction conditions. The 3‐NH is highly acidic and acylation takes place with acid anhydrides at this position in high yields in the presence of pyridine or triethylamine. The diacylation of both the 3‐position and the 5‐amino group was only possible via the 5‐amino‐3‐acyl‐1,3,4‐thiadiazolin‐2‐one intermediates 4. Under neutral conditions, acylation only occurs at the 5‐amino group with acyl chlorides forming 5‐acylamino‐3__H__‐1,3,4‐thiadiazolin‐2‐ones 5. 5‐Acetylamino‐3__H__‐1,3,4‐thiadiazolin‐2‐one can also be synthesized by the thermal transformation of 5‐amino‐3‐acetyl‐1,3,4‐thiadi‐azolin‐2‐one in acetic acid.