Expeditious synthesis of 1,3,4-oxadiazole derivatives via sydnones

Abstract

The clean cyclization of chalcones (1a–c/2a–c) with hydrazine hydrate under microwave irradiation afforded pyrazolines derivatised with sydnone (3d–i/4d–i), which underwent 1,3-dipolar cyclo-addition with acetic anhydride to form pyrazolines appended with 1,3,4-oxadiazoles (5g–l/6g–l). The newly synthesized compounds were confirmed by spectral and elemental analyses. In comparison to classical heating, the results indicate that microwave irradiation affords higher yields, shorter reaction times (4–12 min) and cleaner reactions.

Keywords

• porphyrin microwave irradiation
• sydnones
• chalcones
• pyrazolines
• 1
• 3
• 4-oxadiazoles