Synthesis of 5‐(aroylamino)‐2‐methyl‐2H,‐1,2,4‐thiadiazol‐3‐ones by oxidative cyclization of 1‐aroyl‐5‐methyl‐2‐thiobiurets

Abstract

5‐Aroylamino‐2‐methyl‐2H‐1,2,4‐thiadiazol‐3‐ones 3 have been synthesized by oxidative cyclization of 1‐aroyl‐5‐methyl‐2‐thiobiurets 2 with hydrogen peroxide in an alkaline solution. The needed 1‐aroyl‐5‐methyl‐2‐thiobiurets 2 have been obtained through the addition of methylurea to the corresponding aroyl isothiocyanates.

Thiadiazoles

“…The 5-amino-1,2,4-thiadiazolin-3-one 271, analog of cytosine, can exist in two stable tautomeric forms: lactam (oxo) 271a and lactim (enol) 271b. 13 C and 1 H NMR spectra and ab initio molecular orbital calculations support the idea that 271 exists in the lactam rather than in the lactim form [136,137]. The fully saturated 1,2,4-thiadiazole system (1,2,4-thiadiazolidine) is present in a series of compounds endowed with important biological activities.…”

“…Receptor-ligand binding experiments and stability studies Other oxidizing agents such as molecular bromine [136] or N-bromosuccinimide [188] have been used for cyclization.…”

Design and synthesis of some pyrazole derivatives of expected anti-inflammatory and analgesic activities

“…Nomenclature of presented compounds was according to IUPAC system. Compounds 2a, 5a, and 5b were prepared according to the literature procedures (Slotta and Heller, 1930;Lange et al, 2004;Cho and Shon, 1991), respectively.…”

“…Nucleophilic addition of pyrazoline derivatives 4a and 4b to 4-chlorobenzoyl isothiocyanate 7 (Cho and Shon, 1991) gave the adduct 8a and 8b. IR spectra of 8a and 8b revealed the presence of (C=O) at t 1669 and 1656 cm -1 .…”

“…Compound 7 was prepared according to the reported procedure (Cho and Shon, 1991) from 4-chlorobenzoyl chloride and ammonium thiocyanate and immediately reacted with 4.…”