Synthesis of 1,3,4-Oxadiazoles Having Phenol or Thiophenol Group

Substituted 1,3,4-oxadiazoles are of considerable phar-maceutical and material interest, which is documented by a steadily increasing number of publications and patents. For instance, 2-amino-1,3,4-oxadiazoles act as muscle relaxants1 and show antimitotic activity.2 Analgesic, antiinflammatory, anticonvulsive, diuretic and antiemetic properties are ex-hibited by 5-aryl-2-hydroxymethyl-1,3,4-oxadiazole deriv-atives,3 and 2-hydroxyphenyl-1,3,4-oxadiazole acts as a hypnotic and as a sedative.4 Some material applications of 1,3,4-oxadiazole derivatives lie in the fields of photosensi-tizers5 and liquid crystals.6 The common synthetic approaches to oxadiazoles7 involve cyclization of diacylhydrazines. A variety of reaction condi-tions influence the cyclization reaction. Typically, the reaction is promoted by heat and anhydrous reagents includin