Synthesis and antimicrobial activities of some triazole, thiadiazole, and oxadiazole substituted coumarins

Article abstract of DOI:10.1002/jhet.1745

Ethyl-2-(4-methyl-2-oxo-2-coumarin-7-yloxy)acetate 1 has been prepared from 7-hydroxy-4-methyl-2-coumarin, which on further treatment with hydrazine hydrate in boiling ethanol gave the hydrazide compound 2. The resulting hydrazide was reacted with substituted aryl isothiocyanates to form thiosemicarbazides compounds 3a, 3b, 3c, 3d, 3e. 1-(2-(4-Methyl-2-oxo-2- coumarin-7-yloxy)acetyl)-4-aryl thiosemicarbazides 3 underwent cyclization with different reagents under different reaction conditions to furnish coumarin derivatives possessing triazoles 4a, 4b, 4c, 4d, 4e, thiadiazoles 5a, 5b, 5c, 5d, 5e, and oxadiazoles 6a, 6b, 6c, 6d, 6e, respectively. The structures of all the compounds have been assigned by elemental analysis and spectral studies. The synthesized compounds were screened for their antimicrobial analgesic activities. The nonconventional controlled microwave irradiation synthesis is carried out at (200 W) at 70°C. This approach offers a number of advantages in terms of methodology, high-product yield, short reaction time, mild reaction conditions, environmentally benign, and easy workup.