Aryl-chlorides
and
-fluorides
are
common
building
blocks,
but
their
use
in
synthesis
is
limited
by
the
high
stability
of
Ar-X
bonds.
The
generation
aryl
radicals
via
activation
strong
bonds
possible
through
irradiation
tailor-made
organic
anions,
which
become
reductants
stronger
than
lithium
metal.
We
report
that
combination
visible
light
with
cheap
diphenylacetic
acid
dianion
an
even
better
tool,
showing
excellent
activity
across
a
variety
complex
substrates
providing
opportunities
for
late-stage
drug
modification.
chemoselectively
activated
presence
more
easily
reducible
functions,
such
as
Alk-Cl
ones
carbonyl
groups,
reminding
Marcus
inverted
region
principle.
These
results
pave
way
to
original
synthetic
strategies
would
be
otherwise
considered
impossible
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(5), С. 2907 - 2912
Опубликована: Янв. 24, 2024
Thioethers,
often
found
in
pharmaceuticals
and
natural
compounds,
typically
involve
metal
cross-coupling
reactions,
high
temperatures,
the
use
of
disagreeable
thiols
for
their
synthesis.
Here
we
present
a
straightforward,
thiol-free
organocatalytic
protocol
that
uses
mild
conditions
to
stitch
together
inexpensive
alcohols
aryl
chlorides,
yielding
diverse
array
alkyl
thioethers.
Central
this
approach
was
discovery
tetramethylthiourea
can
serve
as
simple
sulfur
source
upon
intercepting
photochemically
generated
radicals.
To
form
radicals,
used
readily
available
indole
thiolate
organocatalyst
that,
when
excited
with
405
nm
light,
gained
strongly
reducing
power,
enabling
activation
unreactive
chlorides
via
single-electron
transfer.
Radical
trapping
by
thiourea,
followed
an
alcohol
attack
polar
path,
resulted
formation
thioether
products.
Nature Communications,
Год журнала:
2024,
Номер
15(1)
Опубликована: Янв. 22, 2024
Abstract
The
open-shell
catalytically
active
species,
like
radical
cations
or
anions,
generated
by
one-electron
transfer
of
precatalysts
are
widely
used
in
energy-consuming
redox
reactions,
but
their
excited-state
lifetimes
usually
short.
Here,
a
closed-shell
thioxanthone-hydrogen
anion
species
(
3
),
which
can
be
photochemically
converted
to
potent
and
long-lived
reductant,
is
under
electrochemical
conditions,
enabling
the
electrophotocatalytic
hydrogenation.
Notably,
TfOH
regulate
potential
this
system.
In
presence
TfOH,
precatalyst
1
)
reduction
occur
at
low
potential,
so
that
competitive
H
2
evolution
inhibited,
thus
effectively
promoting
hydrogenation
imines.
absence
reducing
ability
system
reach
potency
even
comparable
Na
0
Li
,
thereby
allowing
hydrogenation,
borylation,
stannylation
(hetero)arylation
aryl
halides
construct
C−H,
C−B,
C−Sn,
C−C
bonds.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(44)
Опубликована: Авг. 16, 2023
Abstract
Electron‐deficient
acridones
and
in
situ
generated
acridinium
salts
are
reported
as
potent,
closed‐shell
photooxidants
that
undergo
surprising
mechanisms.
When
bridging
acyclic
triarylamine
catalysts
with
a
carbonyl
group
(acridones),
this
completely
diverts
their
behavior
away
from
open‐shell,
radical
cationic,
‘beyond
diffusion’
photocatalysis
to
closed‐shell,
neutral,
diffusion‐controlled
photocatalysis.
Brønsted
acid
activation
of
dramatically
increases
excited
state
oxidation
power
(by
+0.8
V).
Upon
reduction
protonated
acridones,
they
transform
electron‐deficient
even
more
potent
(*
E
1/2
=+2.56–3.05
V
vs
SCE).
These
oxidize
arenes
where
conventional
salt
have
thusfar
been
limited
electron‐rich
arenes.
Surprisingly,
upon
photoexcitation
these
appear
two
electron
reductive
quenching
form
acridinide
anions,
spectroscopically‐detected
forms.
This
new
behaviour
is
partly
enabled
by
catalyst
preassembly
the
arene,
contrasts
SET
salts.
Critically,
study
illustrates
how
redox
active
chromophoric
molecules
initially
considered
photocatalysts
can
during
reaction
catalytically
species
different
spectroscopic
properties.
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(21)
Опубликована: Март 14, 2024
Abstract
Dearomative
partial
reduction
is
an
extraordinary
approach
for
transforming
benzenoid
arenes
and
has
been
well‐known
many
decades,
as
exemplified
by
the
dehydrogenation
of
Birch
hydroarylation
Crich
addition.
Despite
its
remarkable
importance
in
synthesis,
this
field
experienced
slow
progress
over
last
half‐century.
However,
a
revival
observed
with
recent
introduction
electrochemical
photochemical
methods.
In
Minireview,
we
summarize
advancements
dearomative
arenes,
including
dihydrogenation,
hydroalkylation,
arylation,
alkenylation,
amination,
borylation
others.
Further,
intriguing
utilization
synthesis
natural
products
also
emphasized.
It
anticipated
that
Minireview
will
stimulate
further
arene
transformations.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
unknown
Опубликована: Апрель 9, 2024
The
C–F
bond
is
the
strongest
covalent
single
(126
kcal/mol)
in
carbon-centered
bonds,
which
highest
electronegativity
of
fluorine
(χ
=
4)
gives
rise
to
shortest
length
(1.38
Å)
and
smallest
van
der
Waals
radius
(rw
1.47
Å),
resulting
enormous
challenges
for
activation
transformation.
Herein,
conversion
was
realized
via
photouranium-catalyzed
hydroxylation
unactivated
aryl
fluorides
using
water
as
a
hydroxyl
source
deliver
multifunctional
phenols
under
ambient
conditions.
featured
cascade
sequences
electron
transfer
(SET)/hydrogen
atom
(HAT)/oxygen
(OAT),
highly
integrated
from
excited
uranyl
cation.
*UO22+
prompted
splitting
mild
photoexcitation,
caging
active
oxygen
peroxo-bridged
manner
critical
OAT
process
releasing
hydrogen
HAT
process.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(40)
Опубликована: Авг. 16, 2023
Abstract
The
facile
construction
of
C(sp
3
)‐rich
carbo‐
and
heterocyclic
compounds
is
a
pivotal
synthetic
strategy
to
foster
contemporary
drug
discovery
programs.
downstream
dearomatization
readily
accessible
two‐dimensional
(2D)
planar
arenes
represents
direct
pathway
towards
accessing
three‐dimensional
(3D)
aliphatic
scaffolds.
Here,
we
demonstrate
that
polysulfide
anions
are
capable
catalyzing
process
substituted
naphthalenes,
indoles,
other
related
heteroaromatic
in
the
presence
potassium
formate
methanol
under
visible
light
irradiation.
developed
protocol
exhibits
broad
functional
group
tolerance,
operational
simplicity,
scalability,
cost‐effectiveness,
representing
practical
sustainable
tool
for
arene
dearomatization.
Organic Chemistry Frontiers,
Год журнала:
2024,
Номер
11(18), С. 5232 - 5277
Опубликована: Янв. 1, 2024
This
review
describes
recent
advances
in
the
generation
of
aryl
radicals
using
light
and
electricity.
Such
modern
techniques
allow
for
efficient
energy
resource
utilization,
thus
providing
more
sustainable
radical
arylation
methods.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
63(1)
Опубликована: Ноя. 14, 2023
Reactions
of
unactivated
alkyl
chlorides
under
mild
and
sustainable
conditions
are
rare
compared
to
those
bromides
or
iodides.
As
a
result,
synthetic
methods
capable
modifying
the
vast
chemical
space
chloroalkane
reagents,
wastes,
materials
limited.
We
report
cobalt-catalyzed
reductive
addition
conjugated
alkenes.
Co-catalyzed
activation
is
performed
electroreductive
conditions,
resulting
reactions
constitute
formal
alkyl-alkyl
bond
formation.
In
developing
an
operationally
simple
methodology,
detailed
mechanistic
studies
provide
insights
into
elementary
steps
proposed
catalytic
cycle.
particular,
we
propose
switch
in
mechanism
C-Cl
from
nucleophilic
substitution
halogen
atom
abstraction,
which
critical
for
efficiently
generating
radicals.
These
were
leveraged
designing
ligands
that
enable
couplings
primary,
secondary,
tertiary
chlorides.
