Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(27), С. 18753 - 18770
Опубликована: Июнь 27, 2024
Herein,
we
report
room
temperature,
atom-economic
protocols
for
high
regio-
and
enantioselective
tandem
cycloisomerization–hydroarylation
cycloisomerization–hydroalkenylation
of
1,6-enynes
leading
to
vicinal
carba-functionalized
pyrrolidines,
tetrahydrofurans,
cyclopentanes.
The
latter
steps
in
these
processes
involve
carbonyl-coordination-assisted
ortho-C–H
activation
aromatic
aldehydes
esters,
and,
a
similar,
yet
rarely
seen,
β-C–H
the
case
acrylates.
Synthetically
useful
versions
such
reactions
are
rare
limited
C2–H
indoles
pyrroles.
A
similar
reaction
is
also
observed
with
N-vinylphthalimide,
which
has
carbonyl
group
suitable
C–H
activation.
dibenzooxaphosphole
ligand,
(2S,2S′,3S,3S′)-MeO-BIBOP
was
uniquely
identified
as
crucial
achieving
challenging
enantioselectivity.
This
methodology
gives
access
substituted
five-membered
carbo-
heterocyclic
compounds
good
yields
excellent
enantioselectivities
under
low
catalyst
loading.
primary
KIE
3.5
an
intermolecular
competition
experiment
methyl
benzoate
d5-methyl
benzoate,
indicates
that
cleavage
turnover-limiting
step
this
process.
Unlike
acrylates,
undergoes
exclusive
hydroalkenylation,
β,
γ-unsaturated
ester,
but-3-enoate,
highly
cycloisomerization-coupling
sequence
1,6-enyne
giving
either
[2
+
2
2]-cycloaddition
(S,
S)-BDPP
or
hydroalkenylation
(2S,2′S,3S,3′S)-MeO-BIBOP
depending
on
ligand
employed.
(E)-configuration
newly
formed
double
bond
at
terminal
alkynyl
carbon
(of
starting
enyne)
product
β,γ-unsaturated
ester
suggests
more
classical
migratory
insertion-β-hydride
elimination
route
formation
product.
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:
2023,
Номер
145(14), С. 7983 - 7991
Опубликована: Март 28, 2023
Conjugate
addition
is
among
the
most
important
synthetic
protocols
for
constructing
carbon
skeletons
and
widely
used
to
synthesize
natural
products
drugs.
However,
asymmetric
catalysis
studies
have
mainly
focused
on
stereogenic
centers
arising
from
conjugate
alkenes.
Here,
we
report
first
photoinduced
cobalt-catalyzed
dynamic
kinetic
reductive
reaction
that
enables
formation
of
heterobiaryls
with
axial
chirality
(45
examples,
up
91%
yield
97%
ee).
This
method
features
mild
conditions,
good
functional-group
tolerance,
excellent
enantiomeric
control.
Significantly,
large
amounts
metal
waste
precious
catalysts
can
be
avoided
under
these
conditions.
Migration
chiral
arylcobalt
species
into
alkene
might
rate-determining
step
based
studies.
Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(7), С. 3915 - 3925
Опубликована: Фев. 10, 2023
The
straightforward
construction
of
stereogenic
centers
bearing
unprotected
functional
groups,
as
in
nature,
has
been
a
persistent
pursuit
synthetic
chemistry.
Abundant
applications
free
enantioenriched
allyl
alcohol
and
hydroxylamine
motifs
have
made
the
asymmetric
hydration
hydroaminoxylation
conjugated
dienes
from
water
hydroxylamine,
respectively,
intriguing
efficient
routes
that
have,
however,
unachievable
thus
far.
A
fundamental
challenge
is
failure
to
realize
transition-metal-catalyzed
enantioselective
C–O
bond
constructions
via
hydrofunctionalization
dienes.
Here,
we
perform
comprehensive
study
toward
stereoselective
formal
by
synthesizing
set
new
P,N-ligands
identifying
an
aryl-derived
oxime
surrogate
for
both
hydroxylamine.
Asymmetric
hydroalkoxylation
with
also
elucidated.
Furthermore,
versatile
derivatizations
following
provide
indirect
but
concise
hydrophenoxylation,
hydrofluoroalkoxylation,
hydrocarboxylation
unreported
Finally,
ligand-to-ligand
hydrogen
transfer
process
proposed
based
on
results
preliminary
mechanistic
experiments.
Journal of the American Chemical Society,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 10, 2025
Achieving
catalytic
asymmetric
functionalization
of
methylenecyclopropanes
(MCPs)
by
selective
C–C
bond
cleavage
is
a
notable
challenge
due
to
the
intricate
reaction
partners
involved.
In
this
work,
we
report
that
chiral
aldehyde/palladium
combined
catalysis
enables
MCPs
with
NH2-unprotected
amino
acid
esters.
This
proceeds
through
regiospecific
branched
ring-opening
mechanism,
resulting
in
optically
active
α,α-disubstituted
α-amino
esters
bearing
nonconjugated
terminal
alkene
units.
Mechanism
studies
indicate
pathways
are
irreversible
and
ultimate
regioselectivity
governed
palladium
catalysis.
The
products
can
be
utilized
construction
dihydropyrazoles,
α-methyl
aspartic
derivatives,
analogues
VPC01091
BMS-986104.
Angewandte Chemie International Edition,
Год журнала:
2019,
Номер
58(40), С. 14245 - 14249
Опубликована: Авг. 7, 2019
Abstract
A
hybrid
transition‐metal/radical
process
is
described
that
results
in
the
addition
of
organozinc
reagents
and
alkyl
halides
across
alkenyl
boron
an
enantioselective
catalytic
fashion.
The
reaction
can
be
accomplished
both
intermolecularly
intramolecularly,
providing
useful
product
yields
high
enantioselectivities
manifolds.
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.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(15), С. 10857 - 10867
Опубликована: Апрель 8, 2024
The
asymmetric
cross-coupling
of
unsaturated
bonds,
hampered
by
their
comparable
polarity
and
reactivity,
as
well
the
scarcity
efficient
catalytic
systems
capable
diastereo-
enantiocontrol,
presents
a
significant
hurdle
in
organic
synthesis.
In
this
study,
we
introduce
highly
adaptable
photochemical
cobalt
catalysis
framework
that
facilitates
chemo-
stereoselective
reductive
cross-couplings
between
common
aldehydes
with
broad
array
carbonyl
iminyl
compounds,
including
N-acylhydrazones,
aryl
ketones,
aldehydes,
α-keto
esters.
Our
methodology
hinges
on
synergistic
mechanism
driven
photoredox-induced
single-electron
reduction
subsequent
radical–radical
coupling,
all
precisely
guided
chiral
catalyst.
Various
optically
enriched
β-amino
alcohols
unsymmetrical
1,2-diol
derivatives
(80
examples)
have
been
synthesized
good
yields
(up
to
90%
yield)
high
stereoselectivities
>20:1
dr,
99%
ee).
Of
particular
note,
approach
accomplishes
unattainable
transformations
disparate
partners
without
reliance
any
external
photosensitizer,
thereby
further
emphasizing
its
versatility
cost-efficiency.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(28), С. 18892 - 18898
Опубликована: Июль 5, 2024
Herein,
we
designed
a
reaction
for
the
desymmetrization-addition
of
cyclopropenes
to
imines
by
leveraging
synergy
between
photoredox
and
asymmetric
cobalt
catalysis.
This
protocol
facilitated
synthesis
series
chiral
functionalized
cyclopropanes
with
high
yield,
enantioselectivity,
diastereoselectivity
(44
examples,
up
93%
yield
>99%
ee).
A
possible
mechanism
involving
cyclopropene
desymmetrization
Co-H
species
imine
addition
Co-alkyl
was
proposed.
study
provides
novel
route
important
extends
frontier
metallaphotoredox