SYNTHESIS OF NEW 5,3/5 AND 2-SUBSTITUTED (1,3,4)-OXADIAZOLES AND THEIR RELATED PRODUCTS AS POTENTIAL ANTIFUNGAL AND ANTIVIRAL AGENTS

Three 5-(6′,8′-disubstituted-2′-ethyl-quinazolin-4'-oxymethyl)-2-mercapto-l,3,4-oxadiazoles (III) were synthesised by the cyclisation of N-(6′,8′-disubstituted-2′-ethyl-quinazolin-4′-oxy-acetyl) hydrazines (I) and two 5-(6′,8′-disubstituted-2′-ethyl-quinazolin-4′-oxy-methyl)-2-phenyl-1,3,4-oxadiazoles (II) were prepared by the compound (I) in the presence of POCl3 and benzoic acid. III undergoes condensation with chloro compounds at position-2 to give IV in the presence of dryacetone and anhyd. potassium carbonate. III also undergoes Mannich condensation at position-3 in the presence of formaldehyde and 3/4-(2′-benzimidazolyl)-anilines and furnished V. All the synthesised compounds were screened against plant virus SRV both in vivo and in vitro for their antiviral action at a conc. 1 mg/ml and found to inhibit 4–48% in vivo and 6–53% in vitro. Four compounds (III 1, IV 3, V 1 and V 2) were screened for their antifungal action against Fusarium sp. and A. niger and three compounds caused a very significant inhibition at a conc. 1:1000.