KrishnaNaik&col.
202
1. INTRODUCTION
Heterocycles bearingnitrogen, oxygenand sulphur atoms in their structure
have received remarkable attention because of their biological and
pharmacological applications [1-‐3]. Among the wide variety of heterocycles that
were explored for developing pharmaceutically important molecules, compounds
containing 1,3,4-‐oxadiazole nucleus [4-‐7] and pyrazole nucleus [8-‐13] constitute
the important class of compounds exhibiting diverse and extensive spectrum of
biological activities. This scenario led us to synthesize the novel compounds VII
and IX containing 1,3,4-‐oxadiazole and pyrazole nuclei and evaluate their
antibacterial andantifungal activities.
2.MATERIALSANDMETHODS
All chemicalsusedwereanalytical gradeobtained fromMerck IndiaLimited,
India. All the glass ware used were of borosilicate grade. The standard bacterial
and fungal stainswereprocured fromNational Centre forCell Science, Pune, India.
UV-‐Visible spectrophotometermanufacturedby ShimadzuCorporation, Japanwas
used for absorption measurements. The IR spectra were recorded on a Perkin-‐
Elmer 983 IR spectrometer. The
1
H-‐NMR spectra were recorded on a Bruker AC
300F (200 MHz) NMR spectrometer using DMSO – d
6
as solvent and TMS as an
internal standard. Mass spectra of the compounds were recorded on a Jeol JMS-‐
D300mass spectrometeroperatingat70eV.
2.1. General SyntheticProcedures
The novel compounds were synthesized by specified procedures and the
critical intermediate compounds were characterized by elemental analysis and
spectral data.
2.1.1. Synthesis of {4-‐[3-‐Methyl-‐5-‐oxo-‐4-‐(4
|
-‐substituted phenyl hydrazono)-‐4,5-‐
dihydro-‐pyrazol-‐1-‐yl]-‐phenoxy}-‐aceticacidhydrazide(V).
a. Synthesisof substitutedphenyl diazoniamchloride(I)
The required primary amine was dissolved in a suitable volume of water
containing 2.5–3.0 equivalents of hydrochloric acid (or sulphuric acid). The
solutionwas cooled to0
o
C. To thecrystalsof aminehydrochloride (or sulphate) so
obtained, anaqueous solutionof sodiumnitritewasaddedportionwise. Anexcess
of acidwas necessary to stabilize the diazonium chloride. Similar procedure was
adopted for thepreparationof other substitutedphenyl diazoniumchlorides.
b. Synthesisof substitutedphenyl diazoniumethyl acetoaceticester (II)
To an ice-‐cold solution of mixture of sodium acetate (1.0 g) in 100 mL of
aqueous alcohol and ethyl acetoacetate (0.1 mol) in 50 mL of ethanol, the
corresponding diazonium chloride was added till yellow crystals were separated
