Green Chemistry,
Год журнала:
2022,
Номер
24(23), С. 9027 - 9032
Опубликована: Янв. 1, 2022
This
work
reports
the
first
visible-light
mediated
cobalt-catalyzed
aldehyde
allylation
with
simple
alkenes
to
produce
homo-allylic
alcohols.
novel
strategy
directly
uses
easily
available
unactivated
as
allyl
sources
instead
of
pre-synthesized
allylic
halides.
Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(12), С. 6944 - 6952
Опубликована: Март 15, 2023
Enantioselective
metallaphotoredox
catalysis,
which
combines
photoredox
catalysis
and
asymmetric
transition-metal
has
become
an
effective
approach
to
achieve
stereoconvergence
under
mild
conditions.
Although
many
impressive
synthetic
approaches
have
been
developed
access
central
chirality,
the
construction
of
axial
chirality
by
still
remains
underexplored.
Herein,
we
report
two
visible
light-induced
cobalt-catalyzed
reductive
couplings
biaryl
dialdehydes
synthesize
axially
chiral
aldehydes
(60
examples,
up
98%
yield,
>19:1
dr,
>99%
ee).
This
protocol
shows
good
functional
group
tolerance,
broad
substrate
scope,
excellent
diastereo-
enantioselectivity.
ACS Catalysis,
Год журнала:
2025,
Номер
unknown, С. 1147 - 1157
Опубликована: Янв. 3, 2025
This
study
describes
a
photoredox/cobalt
dual-catalyzed
asymmetric
Grignard-type
addition
reaction,
enabling
the
synthesis
of
axially
chiral
hexatomic
(six–six)
N-heterobiaryls
bearing
extra
secondary
alcohol
unit
via
an
efficient
dynamic
kinetic
transformation
racemic
N-heterobiaryl
triflate
substrates.
The
conversion
facilitated
both
photoredox
and
classical
reductive
reaction
conditions
exhibits
good
functional
group
tolerance,
broad
substrate
scope,
satisfactory
stereoselectivity.
Furthermore,
control
experiments
density
theory
calculations
provide
preliminary
mechanistic
insights.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(24)
Опубликована: Апрель 12, 2023
Catalytic
metal
hydride
hydrogen
atom
transfer
(MHAT)
reactions
have
proven
to
be
a
powerful
method
for
alkene
functionalization.
This
work
reports
the
discovery
of
Co-porphines
as
highly
efficient
MHAT
catalysts
with
loading
only
0.01
mol
%
unprecedented
chemoselective
allene
functionalization
under
photoirradiation.
Moreover,
newly
developed
bimetallic
strategy
by
combination
photo
Co-MHAT
and
Ti
catalysis
enabled
successful
carbonyl
allylation
wide
range
amino,
oxy,
thio,
aryl,
alkyl-allenes
providing
expedient
access
valuable
β-functionalized
homoallylic
alcohols
in
over
100
examples
exceptional
regio-
diastereoselectivity.
Mechanism
studies
DFT
calculations
supported
that
selectively
transferring
atoms
from
cobalt
allenes
generating
allyl
radicals
is
key
step
catalytic
cycle.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(45)
Опубликована: Сен. 7, 2023
Abstract
Selective
hydroarylation
of
dienes
has
potential
to
provide
swift
access
useful
building
blocks.
However,
most
existing
methods
rely
on
stabilised
by
an
aromatic
group
and
transmetallation
or
nucleophilic
attack
steps
require
electron‐rich
aryl
coupling
partners.
As
such,
there
are
few
examples
which
tolerate
wide‐spread
heteroarenes
such
as
pyridine.
Whilst
allylic
C−H
functionalisation
could
be
considered
alternative
approach,
the
positional
selectivity
unsymmetrical
substrates
is
hard
control.
Here,
we
report
a
general
approach
for
selective
hydropyridylation
under
mild
conditions
using
metal
catalysed
hydrogen‐atom
transfer.
Photoinduced,
reductive
enable
simultaneous
formation
cobalt‐hydride
catalyst
persistent
radical
easily‐synthesised
pyridyl
phosphonium
salts.
This
facilitates
in
traceless
manner
at
C4‐position
wide‐range
pyridine
substrates.
The
mildness
method
underscored
its
functional‐group
tolerance
demonstrated
applications
late‐stage
functionalisation.
Based
combination
experimental
computational
studies,
propose
mechanistic
pathway
proceeds
through
non‐reversible
transfer
(HAT)
from
cobalt
hydride
species
uniquely
presence
other
olefins
due
much
higher
relative
barrier
associated
with
olefin
HAT.
Accounts of Chemical Research,
Год журнала:
2024,
Номер
57(5), С. 726 - 738
Опубликована: Фев. 22, 2024
ConspectusBiologically
active
compounds
and
pharmaceutically
relevant
intermediates
often
feature
sterically
congested
stereogenic
centers,
in
particular,
carbon
stereocenters
that
are
either
tertiary
tetrasubstituted
ones
or
quaternary
nature.
Synthons
comprise
such
bulky
structurally
complex
core
units
of
high
synthetic
value
represent
important
incentives
for
communities
connected
to
drug
discovery
development.
Streamlined
approaches
give
access
a
diverse
set
incorporating
acyclic
relatively
limited,
though
vital.
They
enable
further
exploration
three-dimensional
entities
can
be
designed
implemented
programs,
thereby
extending
the
pool
molecular
properties
is
inaccessible
flat
molecules.
However,
lack
modular
substrates
particular
areas
chemical
space
inspired
us
consider
functionalized
heterocycles
known
as
cyclic
carbonates
carbamates
productive
way
create
crowded
alkenes
stereocenters.In
this
Account,
we
describe
major
approximations
followed
over
course
8
years
using
transition
metal
(TM)
catalysis
an
instrument
control
stereochemical
various
allylic
propargylic
substitution
processes
related
transformations.
Allylic
reactions
empowered
by
Pd-catalysis
utilizing
variety
nucleophiles
discussed,
with
amination
being
seed
all
combined
work.
These
procedures
build
on
vinyl-substituted
(VCCs)
simple
easy-to-access
precursors
highly
nature
compared
synthetically
limited
vinyl
oxiranes.
Overall
these
decarboxylative
conversions
take
place
"linear"
"branched"
regioselectivities
ligand
controlled
offer
wide
scope
functional
scaffolds.
Alternative
approaches,
including
dual
TM/photocatalyzed
transformations,
allowed
expand
repertoire
challenging
stereoselective
conversions.
This
was
achieved
through
key
single-electron
pathways
via
formal
umpolung
intermediates,
resulting
new
types
carbon–carbon
bond
formation
significantly
expanding
reactions.Heterocyclic
substrate
variants
have
triple
groups
were
also
difficult-to-promote
TM
catalysis.
In
processes,
Nishibayashi
laboratory
their
seminal
findings
area,
discovered
reactivity
patterns.
provided
range
different
stereodefined
building
blocks
1,2-diborylated
1,3-dienes
α-allenols
under
Cu-
Ni-catalysis.
realm,
use
lactone-derived
gives
elusive
chiral
γ-amino
acids
lactams
stereofidelity
good
structural
diversity.Apart
from
efforts,
elucidated
some
pertinent
mechanistic
manifolds
operative
transformations
better
understand
limitations
opportunities
specifically
synthons.
We
both
theoretical
experimental
investigations
lead
several
unexpected
outcomes
terms
enantioinduction
models,
catalyst
preactivation,
intimately
rationales
observed
selectivity
profiles.
The
work
communicated
offers
insight
into
unique
carbonates/carbamates
acting
privileged
precursors.
It
may
inspire
other
members
widen
toward
novel
added
development
academic
commercial
settings.
ACS Catalysis,
Год журнала:
2025,
Номер
15(10), С. 8303 - 8316
Опубликована: Май 2, 2025
A
practical
diastereoselective
photoredox
nickel-mediated
allylation
of
aliphatic
and
aromatic
aldehydes
with
Morita-Baylis-Hillman
(MBH)
acetates
is
reported
here.
The
reaction
proceeds
under
visible-light
irradiation
using
MBH
derivatives,
which
are
easily
prepared
from
inexpensive
available
starting
materials,
affording
functionalized
alcohols
as
a
single
diastereoisomer
(>20:1
for
the
syn
diastereoisomer).
popular
organic
dye
3DPAFIPN
used
photocatalyst
in
combination
Hantzsch
ester
presence
catalytic
amount
stable
nickel
complexes
o-phenanthroline
ligand.
shows
broad
scope,
avoiding
use
Ni(0),
well
stoichiometric
metal
reductants
such
Zn
Mn.
relevance
was
confirmed
by
products
rapid
access
to
α-methylene-β-lactones,
useful
intermediates
synthesis
natural
or
biologically
active
relevant
products.
DFT
calculations
suggest
that
allyl
acetate-coordinated
Ni(0)
species
plays
role
catalyst
cycle
operates
through
Ni(0)-Ni(II)-Ni(I)-Ni(0)
pathway.
Angewandte Chemie International Edition,
Год журнала:
2022,
Номер
62(1)
Опубликована: Сен. 30, 2022
A
visible
light-induced
Co-catalyzed
highly
regio-
and
stereoselective
reductive
coupling
of
vinyl
azaarenes
alkynes
has
been
developed.
Notably,
Hünig's
base
together
with
simple
ethanol
successfully
applied
as
the
hydrogen
sources
instead
commonly
used
Hantzsch
esters
in
this
catalytic
photoredox
reaction.
This
approach
considerable
advantages
for
straightforward
synthesis
stereodefined
multiple
substituted
alkenes
bearing
an
azaarene
motif,
such
excellent
regioselectivity
(>20
:
1
>30
examples)
stereoselectivity
E/Z),
broad
substrate
scope
good
functional
group
compatibility
under
mild
reaction
conditions,
which
utilized
concise
natural
product
monomorine
I.
reasonable
pathway
involving
protolysis
cobaltacyclopentene
intermediate
proposed
based
on
mechanistic
studies.
Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(33), С. 15372 - 15382
Опубликована: Авг. 15, 2022
The
Ni/Ir-photocatalyzed
coupling
of
an
aryl
bromide
(ArBr)
with
alkyl
(RBr)
has
been
analyzed
using
in
situ
LED-19F
NMR
spectroscopy.
Four
components
(light,
[ArBr],
[Ni],
[Ir])
are
found
to
control
the
rate
ArBr
consumption,
but
not
product
selectivity,
while
two
([(TMS)3SiH],
[RBr])
independently
rate.
A
major
resting
state
nickel
identified
as
ArNiII(L)Br,
and
13C-isotopic
entrainment
is
used
show
that
complex
undergoes
Ir-photocatalyzed
conversion
products
(Ar-R,
Ar-H,
Ar-solvent)
competition
release
ArBr.
range
competing
absorption
quenching
effects
lead
correlations
between
Ir
Ni
catalyst
loadings
reaction
Differences
Ir/Ni
Beer-Lambert
profiles
allow
be
increased
by
use
a
shorter-wavelength
light
source
without
compromising
selectivity.
minimal
kinetic
model
for
process
allows
simulation
provides
insights
optimization
these
processes
laboratory.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
63(2)
Опубликована: Ноя. 10, 2023
Abstract
We
report
a
mild,
catalytic
method
for
the
intermolecular
reductive
coupling
of
feedstock
dienes
and
styrenes
with
ketones.
Our
conditions
allow
concomitant
formation
cobalt
hydride
species
single‐electron
reduction
Subsequent
selective
hydrogen‐atom
transfer
from
generates
an
allylic
radical
which
can
selectively
couple
persistent
radical‐anion
ketone.
This
radical‐radical
negates
unfavourable
steric
interactions
ionic
pathways
avoids
unstable
alkoxy
previous
olefin‐carbonyl
couplings,
were
limited,
as
result,
to
aldehydes.
Applications
this
novel
straightforward
approach
include
efficient
synthesis
drug
molecules,
key
intermediates
in
site‐selective
late‐stage
functionalisation.
Chinese Journal of Chemistry,
Год журнала:
2023,
Номер
41(23), С. 3253 - 3260
Опубликована: Июль 20, 2023
Comprehensive
Summary
Secondary
alcohols
bearing
both
axial
and
central
chirality
comprise
attractive
biological
activity
exhibit
excellent
chiral
induction
in
asymmetric
reactions.
However,
only
very
limited
catalytic
approaches
were
developed
for
their
synthesis.
We
herein
describe
visible
light‐mediated
cobalt‐catalyzed
reductive
Grignard‐type
addition
of
aryl
iodides
with
axially
prochiral
biaryl
dialdehydes
leading
to
the
direct
construction
secondary
alcohols.
Preliminary
mechanistic
studies
indicate
that
efficient
kinetic
recognition
diastereomers
might
occur
improve
stereoselectivity,
which
open
a
new
avenue
challenging
cascade
multiple
elements.
This
protocol
features
enantio‐
diastereoselectivity,
green
mild
conditions,
simple
operation,
broad
substrate
scope,
providing
modular
platform
synthesis