Abstract
The
cross-coupling
of
two
distinct
C(sp3
)–O
bonds
provides
a
highly
valuable
pathway
for
the
construction
)–C(sp3
)
bonds,
but
it
remains
underdeveloped.
Recently,
we
reported
an
innovative
photoinduced
Zr-catalyzed
carbomagnesiation
reductive
coupling
ethers
with
high
cross-selectivity.
Mechanistic
investigation
reveals
that
photoexcitation
low-valent
zirconocene
facilitates
activation
benzylic
ethers.
This
leads
to
formation
functionalized
Grignard
reagents
downstream
aliphatic
through
SN2-like
pathway.
1
Introduction
2
Concept
Our
Design
on
this
Work
3
Photoinduced
Zr-Catalyzed
Cross-Coupling
Ethers
4
Benzylic
Magnesium
Alkoxide
5
Methods
Mechanism
Investigation
6
Conclusion
Molecules,
Год журнала:
2023,
Номер
28(16), С. 6127 - 6127
Опубликована: Авг. 18, 2023
The
functionalisation
of
C–H
bonds
has
been
an
enormous
achievement
in
synthetic
methodology,
enabling
new
retrosynthetic
disconnections
and
affording
simple
equivalents
for
synthons.
Hydrogen
atom
transfer
(HAT)
is
a
key
method
forming
alkyl
radicals
from
substrates.
Classic
reactions,
including
the
Barton
nitrite
ester
reaction
Hofmann–Löffler–Freytag
reaction,
among
others,
provided
early
examples
HAT.
However,
recent
developments
photoredox
catalysis
electrochemistry
have
made
HAT
powerful
tool
capable
introducing
wide
range
functional
groups
into
bonds.
Moreover,
greater
mechanistic
insights
stimulated
development
increasingly
site-selective
protocols.
Site-selectivity
can
be
achieved
through
tuning
electron
density
at
certain
using
additives,
judicious
choice
reagent,
solvent
system.
Herein,
we
describe
latest
methods
functionalizing
C–H/Si–H/Ge–H
indirect
between
2018–2023,
as
well
critical
discussion
reagents,
aspects,
substrate
scopes,
background
contexts
Angewandte Chemie International Edition,
Год журнала:
2024,
Номер
63(32)
Опубликована: Май 24, 2024
Controlling
the
cross-coupling
reaction
between
two
different
radicals
is
a
long-standing
challenge
due
to
process
occurring
statistically,
which
would
lead
three
products,
including
homocoupling
products
and
one
product.
Generally,
selectivity
achieved
by
persistent
radical
effect
(PRE)
that
requires
presence
of
transient
radical,
thus
resulting
in
limited
precursors.
In
this
paper,
highly
selective
alkyl
with
acyl
construct
C(sp
Organometallics,
Год журнала:
2024,
Номер
43(16), С. 1662 - 1681
Опубликована: Апрель 17, 2024
C(sp3)–C(sp3)
bond
formation
is
gaining
more
prominence,
especially
with
a
growing
emphasis
on
building
three-dimensional
chemical
space
in
bioactive
molecules,
fine
chemicals,
and
agrichemicals.
Metallaphotoredox
catalysis
has
emerged
as
an
effective
strategy
for
designing
processes
using
diverse
C(sp3)
precursors
well
suited
1e–
radical
chemistry.
This
review
summarizes
the
latest
advancement
metallaphotoredox
catalysis,
addressing
long-standing
challenges
cross-coupling,
focus
classification
of
reactions
based
distinct
modes
activation
precursor
upon
entering
catalytic
cycle.
Due
to
their
prevalence
in
pharmaceuticals
and
natural
products,
vicinally
functionalized
motifs
are
highly
sought-after.
Traditionally,
these
fragments
synthesized
from
alkene
precursors
via
oxidation
reactions.
However,
complementary
syntheses
a
C–C
bond-forming
approach
underexplored.
Herein,
we
disclose
unified
for
accessing
by
acetal
reagents
made
affordable,
prefunctionalized
starting
materials.
We
have
demonstrated
the
wide
applicability
of
this
methodology
variety
molecularly
complex
substrates.
Additionally,
coupled
products
can
be
employed
one-pot
cyclizations
synthesize
lactones.
We
present
a
photoredox
and
alkylamine-assisted
approach
for
the
selective
hydrochlorination
acylation
of
sp3
C–O
bonds
in
alkynyl
methyl
ethers
using
aldehydes.
This
method
leverages
cascade
radical
processes─including
chlorine
addition,
hydrogen
atom
transfer,
situ
imine
spin-center
shift─to
enable
alkynes
spontaneous
cleavage
bonds.
The
transformation
accommodates
broad
range
internal
alkyne-tethered
aldehydes,
providing
an
efficient
streamlined
pathway
to
chloro-alkenyl
ketones.
Utilizing
only
photocatalyst,
chloride,
propylamine
under
light
irradiation,
this
strategy
offers
practical
complementary
alternative
previous
protocols.
Chemistry - An Asian Journal,
Год журнала:
2025,
Номер
unknown
Опубликована: Май 29, 2025
Abstract
The
selective
activation
and
functionalization
of
robust
C(sp
3
)─O
bonds
in
diols
remains
a
formidable
challenge
organic
synthesis
due
to
their
high
bond
dissociation
energies
poor
leaving
group
properties.
In
this
study,
we
report
regioselective
radical
deoxygenative
strategy
for
the
six‐membered
larger
cyclic
acetals
derived
from
vicinal
diols,
leading
deconjugated
alkenes
under
mild,
visible‐light‐driven
conditions.
methodology
exhibits
broad
substrate
scope
with
respect
both
alkynes,
delivering
variety
alkene
products
moderate
excellent
yields
regioselectivity.
Mechanistic
studies,
including
trapping,
isotopic
labeling,
density
functional
theory
(DFT)
calculations,
provide
strong
evidence
sequential
hydrogen
atom
transfer
(RHAT)/radical
addition/RHAT/C─O
cleavage
sequence.
This
work
introduces
new
platform
site‐selective
highlights
potential
RHAT‐enabled
strategies
C─O
activation.
Abstract
Aldehydes
and
ketones
are
two
of
the
most
versatile
functional
groups
in
organic
synthesis,
development
new
reagents
protocols
to
install
them
always
warranted.
Recently,
reemergence
radical
chemistry
has
provided
opportunities
introduce
these
important
carbonyl
motifs.
As
such,
acetal
radicals
can
be
employed
as
synthetic
equivalents
for
acyl
that
also
circumvent
known
stability
challenges.
This
review
aims
summarize
advancements
uses
radicals,
well
explore
formation
applications.
Angewandte Chemie,
Год журнала:
2024,
Номер
136(32)
Опубликована: Май 24, 2024
Abstract
Controlling
the
cross‐coupling
reaction
between
two
different
radicals
is
a
long‐standing
challenge
due
to
process
occurring
statistically,
which
would
lead
three
products,
including
homocoupling
products
and
one
product.
Generally,
selectivity
achieved
by
persistent
radical
effect
(PRE)
that
requires
presence
of
transient
radical,
thus
resulting
in
limited
precursors.
In
this
paper,
highly
selective
alkyl
with
acyl
construct
C(sp
2
)−C(sp
3
)
bonds,
or
bonds
have
been
readily
available
carboxylic
acids
their
derivatives
(NHPI
ester)
as
coupling
partners.
The
success
originates
from
use
tridentate
ligand
(2,2′
:
6′,2′′‐terpyridine)
enable
Ni‐mediated
organometallic
mechanism.
This
protocol
offers
facile
flexible
access
structurally
diverse
ketones
(up
90
%
yield),
also
new
solution
for
challenging
double
decarboxylative
coupling.
broad
utility
functional
group
tolerance
are
further
illustrated
late‐stage
functionalization
natural‐occurring
drugs.
