Page 208 - 80_01
P. 208
Krishna
Naik&
col.
1.
INTRODUCTION
Heterocycles
bearing
nitrogen,
oxygen
and
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
and
antifungal
activities.
2.
MATERIALS
AND
METHODS
All
chemicals
used
were
analytical
grade
obtained
from
Merck
India
Limited,
India.
All
the
glass
ware
used
were
of
borosilicate
grade.
The
standard
bacterial
and
fungal
stains
were
procured
from
National
Centre
for
Cell
Science,
Pune,
India.
UV--Visible
spectrophotometer
manufactured
by
Shimadzu
Corporation,
Japan
was
used
for
absorption
measurements.
The
IR
spectra
were
recorded
on
a
Perkin--
Elmer
983
IR
spectrometer.
The
1H--NMR
spectra
were
recorded
on
a
Bruker
AC
300F
(200
MHz)
NMR
spectrometer
using
DMSO
–
d6
as
solvent
and
TMS
as
an
internal
standard.
Mass
spectra
of
the
compounds
were
recorded
on
a
Jeol
JMS--
D300
mass
spectrometer
operating
at
70
eV.
2.1.
General
Synthetic
Procedures
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}--acetic
acid
hydrazide
(V).
a.
Synthesis
of
substituted
phenyl
diazoniam
chloride
(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
solution
was
cooled
to
0
oC.
To
the
crystals
of
amine
hydrochloride
(or
sulphate)
so
obtained,
an
aqueous
solution
of
sodium
nitrite
was
added
portion
wise.
An
excess
of
acid
was
necessary
to
stabilize
the
diazonium
chloride.
Similar
procedure
was
adopted
for
the
preparation
of
other
substituted
phenyl
diazonium
chlorides.
b.
Synthesis
of
substituted
phenyl
diazonium
ethyl
acetoacetic
ester
(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
2
02
