Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(43), С. 20056 - 20066
Опубликована: Окт. 20, 2022
The
catalysis
by
a
π-allyl-Co/Ni
complex
has
drawn
significant
attention
recently
due
to
its
distinct
reactivity
in
reductive
Co/Ni-catalyzed
allylation
reactions.
Despite
success
reaction
development,
the
critical
oxidative
addition
mechanism
form
remains
unclear.
Herein,
we
present
study
investigate
this
process
with
four
catalysis-relevant
complexes:
Co(MeBPy)Br2,
Co(MePhen)Br2,
Ni(MeBPy)Br2,
and
Ni(MePhen)Br2.
Enabled
an
electroanalytical
platform,
Co(I)/Ni(I)
species
were
found
responsible
for
of
allyl
acetate.
Kinetic
features
different
substrates
characterized
through
linear
free-energy
relationship
(Hammett-type)
studies,
statistical
modeling,
DFT
computational
study.
In
process,
coordination-ionization-type
transition
state
was
proposed,
sharing
similar
feature
Pd(0)-mediated
Tsuji–Trost
Computational
ligand
structural
analysis
studies
support
mechanism,
which
should
provide
key
information
next-generation
catalyst
development.
Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(18), С. 8347 - 8354
Опубликована: Апрель 28, 2022
Grignard
addition
is
one
of
the
most
important
methods
used
for
syntheses
alcohol
compounds
and
has
been
known
over
a
hundred
years.
However,
research
on
asymmetric
catalysis
relies
use
organometallic
nucleophiles.
Here,
we
report
first
visible-light-induced
cobalt-catalyzed
reductive
Grignard-type
synthesizing
chiral
benzyl
alcohols
(>50
examples,
up
to
99%
yield,
ee).
This
methodology
advantages
mild
reaction
conditions,
good
functionality
tolerance,
excellent
enantiocontrol,
avoidance
mass
metal
wastes,
precious
catalysts.
Kinetic
realization
studies
suggested
that
migratory
insertion
an
aryl
cobalt
species
into
aldehyde
was
rate-determining
step
reaction.
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.
Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(12), С. 5233 - 5240
Опубликована: Март 17, 2022
Catalytic
sequential
hydrosilylation
of
1,3-enynes
and
1,4-enynes
promoted
by
cobalt
complexes
derived
from
bisphosphines
are
presented.
Site-
stereoselective
Si–H
addition
primary
silanes
to
followed
intramolecular
diastereo-
enantioselective
afforded
enantioenriched
cyclic
alkenylsilanes
with
simultaneous
construction
a
carbon-stereogenic
center
silicon-stereogenic
center.
Reactions
proceeded
through
isomerization
the
alkene
moiety
site-
hydrosilylation.
A
wide
range
were
in
high
efficiency
selectivity.
Functionalization
containing
stereogenic
at
silicon
delivered
variety
chiral
building
blocks
that
otherwise
difficult
access.
Angewandte Chemie International Edition,
Год журнала:
2022,
Номер
61(30)
Опубликована: Май 24, 2022
Abstract
One
of
the
most
straightforward
approaches
to
access
chiral
silanes
is
catalytic
enantioselective
hydrosilylation.
Although
significant
advances
have
been
achieved
in
construction
either
a
carbon‐stereogenic
center
or
silicon‐stereogenic
through
hydrosilylation,
simultaneous
establishment
carbon‐
and
an
acyclic
molecule
single
intermolecular
hydrosilylation
remained
undeveloped.
Herein,
unprecedented
cobalt‐catalyzed
regio‐,
diastereo‐
1,3‐dienes
presented,
enabling
transformation.
A
wide
range
bearing
were
generated
high
efficiency
stereoselectivity.
Functionalization
enantioenriched
delivered
variety
valuable
building
blocks
that
are
otherwise
difficult
access.
Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(24), С. 10912 - 10920
Опубликована: Июнь 8, 2022
Metallaphotoredox
chemistry
has
recently
witnessed
a
surge
in
interest
within
the
field
of
synthetic
organic
through
use
abundant
first-row
transition
metals
combined
with
suitable
photocatalysts.
The
intricate
details
arising
from
combination
two
(or
more)
catalytic
components
during
reaction
and
especially
inter-catalyst
interactions
remain
poorly
understood.
As
representative
example
process
featuring
such
intricacies,
we
here
present
meticulous
study
mechanism
cobalt-organophotoredox
catalyzed
allylation
aldehydes.
Importantly,
commonly
proposed
elementary
steps
reductive
metallaphotoredox
are
more
complex
than
previously
assumed.
After
initial
quenching,
transient
charge-transfer
forms
that
interacts
both
transition-metal
catalyst
base.
Surprisingly,
former
interaction
leads
to
deactivation
due
induced
charge
recombination,
while
latter
promotes
deprotonation
electron
donor,
which
is
crucial
step
initiate
productive
catalysis
but
often
neglected.
Due
low
efficiency
this
process,
overall
photon-limited
cobalt
remains
dual
resting
state,
awaiting
photoinduced
reduction.
These
new
insights
general
importance
community,
as
become
powerful
tool
used
formation
elusive
compounds
carbon–carbon
bond
formations.
Understanding
underlying
aspects
determine
reactions
provides
conceptually
stronger
reactivity
paradigm
empower
future
approaches
challenges
rely
on
catalysis.
Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(50), С. 23001 - 23009
Опубликована: Дек. 8, 2022
A
new
regio-
and
stereoselective
reductive
coupling
of
alkynes
crotononitrile
has
been
developed
via
visible
light
organophotoredox
cobalt
dual
catalysis.
variety
enantioenriched
homoallylic
nitriles
bearing
a
stereodefined
trisubstituted
alkene
have
easily
synthesized
with
good
to
excellent
(up
>20:1
rr),
stereo-
(>20:1
E/Z),
enantioselectivity
98%
ee)
control
under
mild
conditions.
The
corresponding
nitrile
products
were
smoothly
converted
into
various
chiral
building
blocks.
Remarkably,
simple
organic
base
together
water
utilized
as
hydrogen
sources
in
this
photoinduced
reaction.
Chemical Reviews,
Год журнала:
2023,
Номер
123(20), С. 11817 - 11893
Опубликована: Окт. 4, 2023
Enantioconvergent
catalysis
has
expanded
asymmetric
synthesis
to
new
methodologies
able
convert
racemic
compounds
into
a
single
enantiomer.
This
review
covers
recent
advances
in
transition-metal-catalyzed
transformations,
such
as
radical-based
cross-coupling
of
alkyl
electrophiles
with
nucleophiles
or
alkylmetals
and
reductive
two
mainly
under
Ni/bis(oxazoline)
catalysis.
C–H
functionalization
can
be
performed
an
enantioconvergent
manner.
Hydroalkylation
alkenes,
allenes,
acetylenes
is
alternative
reactions.
Hydrogen
autotransfer
been
applied
amination
alcohols
C–C
bond
forming
reactions
(Guerbet
reaction).
Other
metal-catalyzed
involve
addition
allylic
systems
carbonyl
compounds,
propargylation
phenols,
3-bromooxindoles,
allenylation
allenolates
propargyl
bromides,
hydroxylation
1,3-dicarbonyl
compounds.
Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(6), С. 3588 - 3598
Опубликована: Фев. 3, 2023
Catalytic
enantioselective
functionalization
of
cyclobutenes
constitutes
a
general
and
modular
strategy
for
construction
enantioenriched
complex
cyclobutanes
bearing
multiple
stereogenic
centers,
as
chiral
four-membered
rings
are
common
motifs
in
biologically
active
molecules
versatile
intermediates
organic
synthesis.
However,
synthesis
through
such
remained
significantly
limited.
Herein,
we
report
series
unprecedented
cobalt-catalyzed
carbon-carbon
bond
forming
reactions
that
initiated
carbometalation.
The
protocols
feature
diastereo-
introduction
allyl,
alkynyl,
functionalized
alkyl
groups.
Mechanistic
studies
indicated
an
unusual
1,3-cobalt
migration
subsequent
β-carbon
elimination
cascade
process
occurred
the
allyl
addition.
These
new
discoveries
established
elementary
cobalt
catalysis
extension
diversity
nucleophiles
transformations
cyclobutenes.
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.