Asian Journal of Organic Chemistry,
Год журнала:
2022,
Номер
12(1)
Опубликована: Дек. 15, 2022
Abstract
An
efficient
synthesis
of
densely
1,2,4‐triazoles
has
been
achieved
by
[3+2]
cycloaddition
nitrileimides
with
amidine
hydrochlorides
under
transition
metal‐free
conditions.
This
method
features
mild
reaction
conditions,
wide
substrate
scope
and
good
functional
group
tolerance.
A
series
aryl,
heterocyclic
alkyl
substituted
3‐CF
3
‐1,2,4‐triazoles
were
synthesized
smoothly
the
promotion
NaHCO
yield
up
to
96%.
In
addition,
both
gram‐scale
synthetic
transformations
are
elaborated
indicate
utility
this
reaction.
Chemistry - An Asian Journal,
Год журнала:
2022,
Номер
17(15)
Опубликована: Май 23, 2022
Here
we
present
a
quadruple
functionalization
approach
for
the
modular
construction
of
fully
substituted
N1
-aryl
3-di/trifluoro-methyl-4/5-cyanopyrazole
pharmacophores
from
readily
available
hydrazonyl
chlorides
and
dicyanoalkenes.
The
realization
this
[3+2]
cycloaddition
reaction
hinges
upon
employment
N-aryl
di/trifluoromethyl
nitrile
imines
as
1,3-dipoles
to
bypass
external
synthetic
steps
dicyanoalkenes
dipolarophiles
tune
regioselectivity.
This
one-pot
strategy
offers
access
divergent
library
cyano
analogues
prevalent
3-di/trifluoromethyl
pyrazole
pharmacophores,
among
which
several
compounds
have
shown
potent
inhibitory
activity
towards
cyclooxygenase
2
(COX-2)
compared
with
marketed
drug
Celecoxib.
Organic & Biomolecular Chemistry,
Год журнала:
2023,
Номер
21(24), С. 5040 - 5045
Опубликована: Янв. 1, 2023
We
describe
the
base-mediated
[3
+
2]
cycloaddition
reaction
of
di/trifluoromethylated
hydrazonoyl
chlorides
with
fluoronitroalkenes
for
synthesis
densely
functionalized
3-di/trifluoroalkyl-5-fluoropyrazoles
potent
biological
activity.
Organic Letters,
Год журнала:
2023,
Номер
25(24), С. 4462 - 4467
Опубликована: Июнь 13, 2023
A
synthetically
useful
approach
for
one-pot
preparation
of
1-aryl-3-trifluoromethylpyrazoles
using
in
situ
generated
nitrile
imines
and
mercaptoacetaldehyde
applied
as
1
equiv
acetylene
is
presented.
This
protocol
comprises
(3
+
3)-annulation
the
mentioned
reagents
to
form
5,6-dihydro-5-hydroxy-4H-1,3,4-thiadiazine,
followed
by
cascade
dehydration/ring
contraction
reactions
with
p-TsCl.
In
addition,
representative
nonfluorinated
analogues
functionalized
Ph,
Ac,
CO2Et
groups
at
C(3)-position
pyrazole
ring
were
also
prepared
devised
method.
The Journal of Organic Chemistry,
Год журнала:
2022,
Номер
87(21), С. 14514 - 14522
Опубликована: Окт. 20, 2022
A
base-mediated
(3
+
2)
cycloaddition
of
trifluoroacetohydrazonoyl
chlorides
with
imidates
for
the
construction
3-trifluoromethyl-1,2,4-triazoles
has
been
described.
This
reaction
is
characterized
by
readily
starting
materials,
simple
conditions,
good
yields,
a
broad
substrate
scope,
and
excellent
regioselectivity.
The
utility
this
protocol
validated
synthesis
drug-like
molecule.
Helvetica Chimica Acta,
Год журнала:
2024,
Номер
107(7)
Опубликована: Апрель 30, 2024
Abstract
The
review
covers
the
results
of
studies
published
in
literature
on
use
hydrazonoyl
halides
synthesis
five‐
(pyrazoles,
thiazoles,
triazoles,
oxa‐
and
thiadiazoles),
six‐
(oxa‐
thiadiazines,
indazoles,
pyridazines,
pyrazines,
tetrazines)
or
seven‐membered
(benzotriazepine)
heterocycles.
In
formation
these
heterocycles,
main
intermediate
stage
reaction
is
situ
generation
nitrilimine,
which
enters
into
a
cycloaddition
with
substituted
acetylenes
(including
generated
benzynes,
naphthynes),
allenes,
activated
olefins,
anthranilic
acid
derivatives,
organosulfur
compounds
(mercaptoaldehydes,
mercaptocarboxylic
acids)
fused
Examples
are
given
heterocycles
by
replacing
halogen
atom
from
halide
molecule
nucleophilic
group,
followed
exhaustive
intramolecular
cyclization
target
compound.
There
discussions
reactions
nitrilimine
to
synthesized
Knoevenagel
condensation
product
(from
CH‐acid
compounds,
such
as
di‐
monocarbonyl
dinitrile
malonic
acid)
occurs,
leading
spiro‐linked
conventional
pyrazoles.
Some
syntheses
biologically
active
representatives
shown.
Asian Journal of Organic Chemistry,
Год журнала:
2022,
Номер
11(11)
Опубликована: Окт. 11, 2022
Abstract
Difluoroacetohydrazonoyl
bromides,
which
are
stable
in
air
at
room
temperature,
demonstrated
to
be
good
difluoromethyl
building
blocks
for
construction
of
CF
2
H‐substituted
pyrazoline
and
pyrazole
compounds
via
[3+2]
cycloaddition
with
electron‐deficient
olefins
under
mild
conditions.
A
series
pyrazolines
pyrazoles
were
obtained
yields.
The
method
has
the
advantages
reaction
conditions,
regioselectivity,
broad
substrate
scopes
easy
operation.
The Journal of Organic Chemistry,
Год журнала:
2023,
Номер
88(15), С. 11258 - 11262
Опубликована: Июль 21, 2023
A
facile
access
to
5-aryl-3-trifluoromethylpyrazoles
has
been
developed
by
a
one-pot
(3
+
2)
cycloaddition-isomerization-oxidation
sequence
employing
2,2,2-trifluorodiazoethane
and
styryl
derivatives.
broad
variety
of
functional
groups
good
yields
are
achieved
under
mild
conditions.
Additionally,
the
functionalization
3-trifluoromethylpyrazoles
was
studied.
DFT
calculations
cycloaddition
transition
state
energies
consistent
with
experimentally
observed
reactivity.
