Synthesis, antimicrobial and antiinflammatory activities of 1,3,4-oxadiazoles linked to naphtho[2,1-<i style="">b</i>]furan

Abstract

Condensation of naphtho[2,1-<i style="">b</i>]furan-2-carboxyhydrazide <b style="">1</b> with different aromatic aldehydes affords the corresponding <i style="">N</i>¹-[(1<i style="">E</i>)-arylmethylene]-naphtho[2,1-<i style="">b</i>]furan-2-carboxyhydrazides <b style="">2a-h</b>. These compounds undergo cyclization with acetic anhydride and mercuric oxide to yield 3-acetyl-5-naphtho[2,1-<i style="">b</i>]furan-2-yl-2-aryl-2,3-dihydro-1,3,4-oxadiazoles <b style="">3a-h</b> and 2-naphtho[2,1-<i style="">b</i>]furan-2-yl-5-aryl-1,3,4-oxadiazoles <b style="">4a-h</b> respectively. The compound <b style="">1</b> on refluxing with carbon disulphide and ethanolic potassium hydroxide followed by acidification with hydrochloric acid furnishes 5-naphtho[2,1-<i style="">b</i>]furan-2-yl-1,3,4-oxadiazole-2(3<i style="">H</i>)-thione <b style="">5</b>. It is converted into Mannich bases 3-(anilinomethyl)-5-naphtho[2,1-<i style="">b</i>]furan-2-yl-1,3,4-oxadiazole-2(3<i style="">H</i>)-thiones <b style="">6a-h</b> on treatment with formaldehyde and appropriate aromatic amines. All the newly synthesized compounds are characterized by elemental analysis and spectral studies. The selected compounds have been screened for their antimicrobial and anti-inflammatory activities.