Synthesis and antioxidant activity of 2-amino-5-R-1,3,4-oxadiazoles with hindered phenol fragments

Compounds with hindered phenolic moiety are known to be effective inhibitors of oxidative processes in different materials, moreover a number of phenols found to show wide spectrum of biological activity. At the same time, five-membered heterocycles exhibit unique properties, including antioxidant activity. One of the ways to create new effective antioxidants with a set of useful properties is to combine hindered phenol and a heterocyclic fragment in one molecule.

In this work new 1-acyl-4-R-thiosemicarbazides were obtained during the reaction between 3-(4-hydroxy-3,5-di-tert-butylphenyl) propanoic acid hydrazide and a number of isothiocyanates. 2-Amino-5-R-1,3,4-oxadiazoles were prepared in good yelds by heterocyclization of 1-acyl-4-R-thiosemicarbazides in presence of iodoxybenzoic acid ant triethylamine. The antioxidant activity of 1,3,4-oxadiazoles was studied in vitro and was found to be higher than that of 4-methyl-2,6-di-tert-butylphenol.