Angewandte Chemie International Edition,
Год журнала:
2021,
Номер
60(52), С. 27164 - 27170
Опубликована: Окт. 21, 2021
Described
herein
is
a
novel
Brønsted
acid
catalyzed
intramolecular
hydroalkoxylation/Claisen
rearrangement,
allowing
the
practical
and
atom-economic
synthesis
of
range
valuable
spirolactams
from
readily
available
ynamides
in
generally
good
to
excellent
yields
with
diastereoselectivities
broad
substrate
scope.
Importantly,
an
unexpected
dearomatization
nonactivated
arenes
heteroaromatic
compounds
involved
this
tandem
sequence.
Moreover,
asymmetric
version
cyclization
was
also
achieved
by
efficient
kinetic
resolution
chiral
phosphoric
catalysis.
In
addition,
[3,3]-rearrangement
shown
be
kinetically
preferred
over
related
[1,3]-rearrangement
theoretical
calculations.
Chemical Reviews,
Год журнала:
2021,
Номер
122(2), С. 2487 - 2649
Опубликована: Ноя. 9, 2021
Redox
processes
are
at
the
heart
of
synthetic
methods
that
rely
on
either
electrochemistry
or
photoredox
catalysis,
but
how
do
and
catalysis
compare?
Both
approaches
provide
access
to
high
energy
intermediates
(e.g.,
radicals)
enable
bond
formations
not
constrained
by
rules
ionic
2
electron
(e)
mechanisms.
Instead,
they
1e
mechanisms
capable
bypassing
electronic
steric
limitations
protecting
group
requirements,
thus
enabling
chemists
disconnect
molecules
in
new
different
ways.
However,
while
providing
similar
intermediates,
differ
several
physical
chemistry
principles.
Understanding
those
differences
can
be
key
designing
transformations
forging
disconnections.
This
review
aims
highlight
these
similarities
between
comparing
their
underlying
principles
describing
impact
electrochemical
photochemical
methods.
Angewandte Chemie International Edition,
Год журнала:
2020,
Номер
59(26), С. 10266 - 10284
Опубликована: Янв. 16, 2020
Abstract
The
energy
of
visible
photons
and
the
accessible
redox
potentials
common
photocatalysts
set
thermodynamic
limits
to
photochemical
reactions
that
can
be
driven
by
traditional
visible‐light
irradiation.
UV
excitation
damaging
induce
side
reactions,
hence
or
even
near‐IR
light
is
usually
preferable.
Thus,
photochemistry
currently
faces
two
divergent
challenges,
namely
desire
perform
ever
more
thermodynamically
demanding
with
increasingly
lower
photon
energies.
pooling
low‐energy
address
both
challenges
simultaneously,
whilst
multi‐photon
spectroscopy
well
established,
synthetic
photoredox
chemistry
has
only
recently
started
exploit
processes
on
preparative
scale.
Herein,
we
have
a
critical
look
at
developed
mechanistic
concepts,
discuss
pertinent
experimental
methods,
provide
an
outlook
into
possible
future
developments
this
rapidly
emerging
area.
ACS Central Science,
Год журнала:
2021,
Номер
7(3), С. 432 - 444
Опубликована: Фев. 22, 2021
Asymmetric
catalysis
has
been
recognized
as
the
most
enabling
strategy
for
accessing
chiral
molecules
in
enantioenriched
forms.
Catalytic
asymmetric
dearomatization
is
an
emerging
and
dynamic
research
subject
catalysis,
which
received
considerable
attention
recent
years.
The
direct
transformations
from
readily
available
aromatic
feedstocks
to
structurally
diverse
three-dimensional
polycyclic
make
catalytic
reactions
of
broad
interest
both
organic
synthesis
medicinal
chemistry.
However,
inherent
difficulty
disruption
aromaticity
demands
a
large
energy
input
during
process,
might
be
incompatible
with
conditions
generally
required
by
catalysis.
In
this
Outlook,
we
will
discuss
representative
strategies
examples
various
compounds
try
convince
readers
that
overcoming
above
obstacles,
could
advance
chemical
sciences
many
respects.
Journal of the American Chemical Society,
Год журнала:
2020,
Номер
142(31), С. 13573 - 13581
Опубликована: Июль 14, 2020
The
Birch
reduction
is
a
powerful
synthetic
methodology
that
uses
solvated
electrons
to
convert
inert
arenes
1,4-cyclohexadienes-valuable
intermediates
for
building
molecular
complexity.
reductions
traditionally
employ
alkali
metals
dissolved
in
ammonia
produce
electron
the
of
unactivated
such
as
benzene
(
Journal of the American Chemical Society,
Год журнала:
2021,
Номер
143(33), С. 13266 - 13273
Опубликована: Авг. 16, 2021
Since
the
seminal
work
of
Zhang
in
2016,
donor–acceptor
cyanoarene-based
fluorophores,
such
as
1,2,3,5-tetrakis(carbazol-9-yl)-4,6-dicyanobenzene
(4CzIPN),
have
been
widely
applied
photoredox
catalysis
and
used
excellent
metal-free
alternatives
to
noble
metal
Ir-
Ru-based
photocatalysts.
However,
all
reported
reactions
involving
this
chromophore
family
are
based
on
harnessing
energy
from
a
single
visible
light
photon,
with
limited
range
redox
potentials
−1.92
+1.79
V
vs
SCE.
Here,
we
document
unprecedented
discovery
that
fluorophores
can
undergo
consecutive
photoinduced
electron
transfer
(ConPET)
achieve
very
high
reduction
potentials.
One
newly
synthesized
catalysts,
2,4,5-tri(9H-carbazol-9-yl)-6-(ethyl(phenyl)amino)isophthalonitrile
(3CzEPAIPN),
possesses
long-lived
(12.95
ns)
excited
radical
anion
form,
3CzEPAIPN•–*,
which
be
activate
reductively
recalcitrant
aryl
chlorides
(Ered
≈
−1.9
−2.9
SCE)
under
mild
conditions.
The
resultant
radicals
engaged
synthetically
valuable
aromatic
C–B,
C–P,
C–C
bond
formation
furnish
arylboronates,
arylphosphonium
salts,
arylphosphonates,
spirocyclic
cyclohexadienes.
Angewandte Chemie International Edition,
Год журнала:
2019,
Номер
58(40), С. 14289 - 14294
Опубликована: Авг. 5, 2019
The
direct
reduction
of
arenes
and
heteroarenes
by
visible-light
irradiation
remains
challenging,
as
the
energy
a
single
photon
is
not
sufficient
for
breaking
aromatic
stabilization.
Shown
herein
that
accumulation
two
photons
allows
dearomatization
heteroarenes.
Mechanistic
investigations
confirm
combination
energy-transfer
electron-transfer
processes
generates
an
arene
radical
anion,
which
subsequently
trapped
hydrogen-atom
transfer
finally
protonated
to
form
dearomatized
product.
photoreduction
converts
planar
feedstock
compounds
into
molecular
skeletons
are
use
in
organic
synthesis.
