Combination
of
experimental
data
and
results
DFT
calculations
indicates
that
the
catalytic
activity
chalconium
halonium
salts
served
as
sigma-hole
donating
organocatalysts
cannot
be
clearly
estimated
via
analysis
electrostatic
potential
on
catalysts’
sigma-holes
values
catalyst•••TS
intermolecular
interactions,
such
polarization
effects,
charge
transfer,
or
covalency
bonding.
Moreover,
real
effect
might
not
correlate
well
with
Gibbs
free
energies
activation
reactions,
because
solvation
effects
other
competitive
binding
processes
play
at
least
same
even
more
important
role
in
catalysis.
It
was
showed
present
work,
either
can
lead
to
increase
equilibrium
concentration
reactive
catalyst•••electrophile
associates
thus
accelerating
reaction
brings
favorable
generation
catalyst•••nucleophile
species
resulting
suppression
organocatalyst.
Chemistry - A European Journal,
Год журнала:
2023,
Номер
29(69)
Опубликована: Сен. 25, 2023
Chalcogen
bonding
(ChB)
is
the
non-covalent
interaction
occurring
between
chalcogen
atoms
as
Lewis
acid
sites
and
or
groups
of
able
to
behave
bases
through
their
lone
pair
π
electrons.
Analogously
its
sister
halogen
bonding,
high
directionality
this
was
implemented
for
precise
structural
organizations
in
solid
state
solution.
Regarding
catalysis,
ChB
now
accepted
a
new
mode
activation
demonstrated
by
increased
number
examples
last
five
years.
In
family
catalysts,
those
based
on
tellurium
rapidly
appeared
overcome
lighter
sulfur
selenium
counterparts.
review,
we
highlight
properties
tellurium-based
derivatives
solution
summarize
start-of-the-art
applications
catalysis.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(15), С. 10608 - 10620
Опубликована: Апрель 2, 2024
The
use
of
noncovalent
interactions
(NCIs)
has
received
significant
attention
as
a
pivotal
synthetic
handle.
Recently,
the
exploitation
unconventional
NCIs
gained
considerable
traction
in
challenging
reaction
manifolds
such
glycosylation
due
to
their
capacity
facilitate
entry
into
difficult-to-access
sugars
and
glycomimetics.
While
investigations
involving
oxacyclic
pyrano-
or
furanoside
scaffolds
are
relatively
common,
methods
that
allow
selective
synthesis
biologically
important
iminosugars
comparatively
rare.
Here,
we
report
phosphonochalcogenide
(PCH)
catalyze
stereoselective
α-iminoglycosylation
iminoglycals
with
wide
array
glycosyl
acceptors
remarkable
protecting
group
tolerance.
Mechanistic
studies
have
illuminated
counterintuitive
role
catalyst
serially
activating
both
donor
acceptor
up/downstream
stages
through
chalcogen
bonding
(ChB).
dynamic
interaction
chalcogens
substrates
opens
up
new
mechanistic
opportunities
based
on
iterative
ChB
engagement
disengagement
multiple
elementary
steps.
Organic & Biomolecular Chemistry,
Год журнала:
2022,
Номер
21(2), С. 223 - 236
Опубликована: Дек. 6, 2022
The
application
of
chalcogenonium
salts
in
organic
synthesis
has
grown
enormously
the
past
decades
since
discovery
methyltransferase
enzyme
cofactor
S-adenosyl-L-methionine
(SAM),
featuring
a
sulfonium
center
as
reactive
functional
group.
Chalcogenonium
can
be
employed
alkylating
agents,
sources
ylides
and
carbon-centered
radicals,
partners
for
metal-catalyzed
cross-coupling
reactions
organocatalysts.
Herein,
we
will
focus
discussion
on
heavier
(selenonium
telluronium),
presenting
their
utility
synthetic
transformations
and,
whenever
possible,
drawing
comparisons
terms
reactivity
selectivity
with
respective
analogues.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(37)
Опубликована: Май 7, 2024
Abstract
A
general
and
highly
enantioselective
method
for
the
preparation
of
tetra‐substituted
3‐hydroxyphthalide
esters
via
isothiourea‐catalysed
acylative
dynamic
kinetic
resolution
(DKR)
is
reported.
Using
(2
S
,3
R
)‐HyperBTM
(5
mol
%)
as
catalyst,
scope
limitations
this
methodology
have
been
extensively
probed,
with
high
enantioselectivity
good
to
excellent
yields
observed
(>40
examples,
up
99
%,
:
1
er).
Substitution
aromatic
core
within
skeleton,
well
aliphatic
substitution
at
C(3),
readily
tolerated.
diverse
range
anhydrides,
including
those
from
bioactive
pharmaceutically
relevant
acids,
can
also
be
used.
The
in
DKR
process
has
probed
computationally,
a
key
substrate
heteroatom
donor
O⋅⋅⋅acyl‐isothiouronium
interaction
identified
through
DFT
analysis
necessary
enantiodiscrimination.
Abstract
Sulfonium,
selenonium,
telluronium
triflates,
as
well
chloronium,
bromonium,
and
iodonium
triflates
have
been
examined
in
the
model
Schiff
condensation
chalcogen‐
halogen
bond
donating
organocatalysts,
respectively.
The
kinetic
data
indicated
that
catalytic
effect
of
salt
is
provided
via
decrease
enthalpy
activation
reaction,
whereas
–
unexpectedly
caused
by
value
entropy
activation.
In
addition,
it
was
experimentally
shown
activity
sulfonium
selenonium
salts
significantly
lower
than
chloronium
bromonium
salts,
but
latter
pair
species
less
stable
under
reaction
conditions
former
pair.
Organic & Biomolecular Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 1, 2025
Chalconium
and
halonium
salts
catalyze
Schiff
condensation.
Kinetic
data
DFT
calculations
show
that
the
catalytic
activity
correlates
with
maximum
electrostatic
potential
on
σ-holes,
whereas
other
factors
are
less
significant.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(37)
Опубликована: Май 7, 2024
The
development
of
methods
to
allow
the
selective
acylative
dynamic
kinetic
resolution
(DKR)
tetra-substituted
lactols
is
a
recognised
synthetic
challenge.
In
this
manuscript,
highly
enantioselective
isothiourea-catalysed
DKR
morpholinone
and
benzoxazinone-derived
reported.
scope
limitations
methodology
have
been
developed,
with
high
enantioselectivity
good
excellent
yields
(up
89
%,
99
:
1
er)
observed
across
broad
range
substrate
derivatives
incorporating
substitution
at
N(4)
C(2),
di-
spirocyclic
C(5)
C(6),
as
well
benzannulation
(>35
examples
in
total).
process
amenable
scale-up
on
g
laboratory
scale.
factors
leading
selectivity
probed
through
computation,
an
N-C=O⋅⋅⋅isothiouronium
interaction
identified
key
producing
ester
products
enantioenriched
form.
