The Journal of Physical Chemistry A,
Год журнала:
2024,
Номер
unknown
Опубликована: Ноя. 27, 2024
DFT
(M06-2X)
calculations
were
used
to
study
the
NHC-catalyzed
[3
+
3]
cycloaddition
of
enals
with
aminoacrylates.
The
catalytic
cycle
begins
binding
NHC
enal.
Subsequent
intramolecular
proton
transfer
generates
Breslow
intermediate.
This
intermediate
undergoes
an
oxidative
reaction,
leading
formation
acyl
azolium
intermediate,
which
further
reacts
other
substrate
aminoacrylate
via
a
new
C–C
bond
formation.
step
determines
stereoselectivity
current
and
re-face
addition
mode
S-configuration
is
predominant.
Afterward,
sequential
protonation,
deprotonation,
cyclization
form
six-membered
cyclic
upon
elimination
affords
final
product
dihydropyridinone.
computed
enantiomeric
excess
(99.1%
ee)
in
very
good
agreement
experimentally
reported
value
(99%
ee).
origin
enantioselectivity
traced
stronger
LP···π
interactions
between
favored
S-congurational
transition
state.
The Journal of Physical Chemistry A,
Год журнала:
2025,
Номер
unknown
Опубликована: Март 5, 2025
A
theoretical
study
on
the
mechanism,
regioselectivity,
and
enantioselectivity
of
NHC-catalyzed
dearomatizing
annulation
benzoxazoles
with
enals
has
been
conducted
using
density
functional
theory
calculations.
Our
calculated
results
indicate
that
favored
mechanism
occurs
through
eight
reaction
steps:
initial
binding
NHC
to
enals,
followed
by
formation
Breslow
intermediate
via
proton
transfer.
Subsequent
oxidation
generates
α,β-unsaturated
acylazolium
intermediate,
which
can
undergo
Michael
addition
benzoxazoles.
Sequential
protonation/deprotonation/cyclization
produces
six-membered
cyclic
undergoes
catalyst
elimination,
leading
final
product.
DABCO·H+
was
found
play
important
roles
in
transfer
cyclization.
Without
DABCO·H+,
energy
barrier
up
44.2
kcal/mol
for
step
2
is
too
high
be
accessible.
With
corresponding
value
lowered
18.6
kcal/mol.
The
cyclization
7.4
DABCO·H+.
determines
both
regioselectivity.
According
NCI
analysis,
controlled
strong
interactions
(such
as
C-H···O,
C-H···N,
π···π)
between
We
also
discuss
solvent
substituent
effects
role
NHC.
mechanistic
insights
obtained
present
would
help
improving
current
systems
or
designing
new
synthetic
routes.
Organic Letters,
Год журнала:
2024,
Номер
26(4), С. 877 - 882
Опубликована: Янв. 24, 2024
An
asymmetric
desymmetrization
of
fluorene-derived
meso-epoxides
is
disclosed
for
the
construction
chiral
fluorenes
bearing
an
all-carbon
quaternary
stereocenter
at
C9.
This
catalyzed
by
a
(salen)CrIII
complex
via
remote
stereocontrol,
producing
diverse
with
excellent
yields
and
stereoselectivity.
The
practicality
this
protocol
was
demonstrated
through
transformation
obtained
products
to
some
intriguing
enantioenriched
polymerizable
monomers.
In
the
past
few
decades,
N-heterocyclic
carbenes
(NHCs)
open
new
field
of
organocatalysis
in
synthetic
organic
chemistry.
This
review
highlights
dramatic
progress
NHC-catalyzed
C−O
bond
formation
based
on
activation
aldehyde
C(sp2)−H
bonds.
The
oxidative
and
redox
transformations
for
synthesis
various
molecules
with
structural
diversity
complexity
are
summarized.
Furthermore,
methods
strategies
NHC
catalysis
emerging
continuously;
thus,
cooperative
Brønsted
acid,
hydrogen-bonding
catalyst,
transition-metal
photocatalyst
is
also
described.
Catalysts,
Год журнала:
2024,
Номер
14(4), С. 219 - 219
Опубликована: Март 22, 2024
In
the
past
few
decades,
N-heterocyclic
carbenes
(NHCs)
have
opened
new
field
of
organocatalysis
in
synthetic
organic
chemistry.
This
review
highlights
dramatic
progress
NHC-catalyzed
C–O
bond
formation
based
on
activation
aldehyde
C(sp2)–H
bonds.
The
oxidative
and
redox
transformations
for
synthesis
various
molecules
with
structural
diversity
complexity
are
summarized.
Furthermore,
methods
strategies
NHC
catalysis
emerging
continuously;
thus,
cooperative
Brønsted
acid,
hydrogen-bonding
catalyst,
transition-metal
photocatalyst
also
described.
European Journal of Organic Chemistry,
Год журнала:
2024,
Номер
27(46)
Опубликована: Авг. 26, 2024
Abstract
The
chiral
fluorene
fragment
constitutes
one
of
the
most
important
scaffolds
frequently
found
in
numerous
bioactive
molecules,
ligands,
and
advanced
functional
materials
due
to
its
unique
physical
properties.
In
this
context,
various
transition
metal‐
organo‐catalyzed
asymmetric
reactions
have
been
developed
prepare
fluorenes
with
high
optical
purity.
present
mini‐review,
we
summarize
fifteen
years
achievements
catalytic
synthesis
their
derivatives.
Particular
attention
is
given
strategies
used
mechanistic
aspects
some
significant
reactions.
Moreover,
cutting‐edge
developments
silafluorenes
are
also
highlighted.
Chemical Communications,
Год журнала:
2024,
Номер
unknown
Опубликована: Янв. 1, 2024
Herein,
we
have
described
a
novel
organocatalytic
approach
to
access
biologically
important
dihydropyridin-2-ones
in
one-pot
way
with
generally
high
yields
(up
99%)
and
excellent
enantioselectivities
99%
ee).
This
reaction
proceeded
