(3+2) Annulation of amidinothioureas with binucleophile: Synthesis and antimicrobial of 3-phenylamino-5-aryl/alkyl-1,2,4-oxadiazole derivatives

Herein, we report an efficient method for preparation of 3-phenylamino-5-aryl/alkyl-1,2,4-oxadiazole by (3+2) annulation of amidinothioureas with binucleophilic hydroxylamine hydrochloride in the presence of mercury (II) chloride. Desired 3-phenylamino-5-aryl/alkyl-1,2,4-oxadiazole was prepared in good to moderate yields. On the basis of the literature precedence, the mechanism for the formation of 3-phenylamino-5-aryl/alkyl-1,2,4-oxadiazole is proposed. The synthesized compounds were tested for their antimicrobial activity and showed promising inhibition of Gram-positive bacteria (Staphylococcus aureus) and fungi (Candida albicans).