Synthesis and Biological Studies of Bis-Heterocycles

Abstract

Reaction of succinic acid hydrazide with substituted isothiocyanate gave corresponding thiosemicarbazides (IIa-c) in good yields. The acid catalysed cyclodehydration of (IIa) gave corresponding oxadiazole (Va). The base catalysed cyclodehydration of (IIa-c) gave respective bis-triazoles (IIIa-c) and cylisation of (IIa-c) with 99% hydrazine hydrate gave respective N-amino triazoles (VIa-c). Reaction of oxalic acid hydrazide with CS2/KOH gave the corresponding salt (VI). Cyclisatipn of (VI) with hyrazine hydrate and phenyl hydrazine hydrate gave corresponding 4-substituted bis-triazoles (VIIa-b). Treatment of (VI) with CH3I/CH3OH gave the methyl salt (VIII). Prolonged refluxing of (VI) with KOH/ C2H5OH gave bis-5-mercapto-1,2,4-oxadiazole (IX).Treatment of substituted benzoic acid with acid hydrazide in presence of POCl3 yielded 5-substituted oxadiazole (Xa-b). Sample number Xa-b on cyclisation with hydrazine hydrate and phenyl hydrazine hydrate gave (XIa-d). Potassium salt (VI) on treating with substituted aniline gave (XIIa-b). All the above compounds are screened for antimicrobial and anthelmintic activities. They showed moderate to high activity.