Studies on the Effect of Positive and Negative Charges on the 77Se NMR Shifts of Selenones and Selenenyls of N-heterocyclic Carbenes of Imidazolium-4,5-dicarboxylates
Lucas Pruschinski,
Sean Ray Kahnert,
Colin Herzberger
и другие.
The Journal of Organic Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Фев. 4, 2025
1,3-Imidazole-4,5-dicarboxylic
acid
derivatives
were
investigated
with
respect
to
the
properties
of
underlying
N-heterocyclic
carbenes.
Their
selenium
adducts
prepared
as
diesters,
monoesters,
and
dianionic
dicarboxylates.
Se-methylation
yielded
selenenyls
(cationic
selenoethers).
77Se
NMR
shifts
are
considered
a
measure
electronic
carbene.
Since
they
very
sensitive
external
(solvent,
pH,
temperature,
reference
reagent,
method)
internal
parameters
(substituent
effects,
steric
nonclassical
H-bonding,
anisotropy),
difficulties
can
arise
in
reliably
interpreting
these
values.
Our
model
compounds
allow
systematic
investigation
influence
charges
on
since
both
structural
changes
measurement
conditions
have
been
minimized.
Depending
charge,
cover
range
from
42.1
ppm
(dianionic
dicarboxylate)
via
65.0
(monoanionic
92.5
(neutral
diester)
153.8
selenoether)
DMSO-d6.
The
signals
also
show
considerable
solvent
pH
dependence,
which
was
selection
solvents
(MeOD,
CDCl3,
CD2Cl2,
CD3COOD,
CD3CN,
acetone-d6,
THF-d8,
pyridine-d5,
toluene-d8,
DMSO-d6)
values
D2O.
Linear
relationships
found
between
HOMO
LUMO
energies
shifts,
respectively.
Язык: Английский
Iodine/Oxone® oxidative system for the Synthesis of Selenylindoles Bearing Benzenesulfonamide Moiety as Carbonic Anhydrase I, II, IX, and XII Inhibitors
Organic & Biomolecular Chemistry,
Год журнала:
2024,
Номер
22(32), С. 6532 - 6542
Опубликована: Янв. 1, 2024
A
wide
range
of
3-selenylindoles
were
synthesized
Язык: Английский
Five Hypotheses on the Origins of Temperature Dependence of 77Se NMR Shifts in Diselenides
Inorganic Chemistry,
Год журнала:
2024,
Номер
63(26), С. 12063 - 12072
Опубликована: Июнь 14, 2024
Notable
thermal
shifts
in
diselenides
have
been
documented
77Se
NMR
for
more
than
50
years,
but
no
satisfactory
explanation
has
found.
Here,
five
hypotheses
are
considered
as
possible
explanations
the
large
temperature
dependence
of
chemical
diaryl
and
dialkyl
compared
to
monoselenides
selenols.
Density
functional
theory
calculations
provided
bolster
better
understand
effects
barrier
height
dipole
energies.
It
is
proposed
that
diselenide
due
rotation
around
Se–Se
bond
sampling
twisted
conformers
at
higher
temperatures.
The
molecular
twisting
solvent
dependent;
here,
DMSO-d6
toluene-d8
were
evaluated.
No
correlation
was
established
between
para-substituents
on
magnitude
change
shift
(Δδ)
with
temperature.
Язык: Английский
Anionic N-Heterocyclic Carbenes from Mesoionic Imidazolium-4-pyrrolides: The Influence of Substituents, Solvents, and Charge on their 77Se NMR Chemical Shifts
The Journal of Organic Chemistry,
Год журнала:
2024,
Номер
unknown
Опубликована: Окт. 3, 2024
Mesoionic
compounds
are
the
starting
material
for
synthesis
of
unique
anionic
N-heterocyclic
carbenes.
Herein,
mesoionic
imidazolium
pyrrolides
synthesized
from
pyrrole-2-carbaldehyde
via
various
Язык: Английский
77Se NMR spectroscopy of selenium adducts of N-heterocyclic carbenes
Advances in heterocyclic chemistry,
Год журнала:
2024,
Номер
unknown
Опубликована: Янв. 1, 2024
Язык: Английский
Cyclopropanation of Aryl and Styryl Acetonitriles With Selenium‐Based Dielectrophiles
European Journal of Organic Chemistry,
Год журнала:
2024,
Номер
27(21)
Опубликована: Апрель 15, 2024
Abstract
Efficient
cyclopropanation
reactions
of
aryl
or
styrylacetonitriles
with
vinyl
selenones
under
mild
conditions
were
described.
By
this
approach,
synthetically
challenging
1‐vinylcyclopropane‐1‐carbonitriles
accessible
in
good
yields.
This
methodology
features
the
advantage
operational
simplicity,
broad
substrate
scope,
functional
group
tolerance,
transition‐metal‐free
conditions,
temperature,
and
a
high
level
regio‐
diastereo‐control.
Язык: Английский