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). Cyclisation 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).Treatrnent 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.