Organometallics,
Год журнала:
2023,
Номер
42(12), С. 1291 - 1299
Опубликована: Март 8, 2023
The
mechanism
of
zirconium-catalyzed
hydroaminoalkylation
diphenylacetylene,
and
the
origin
contrasting
reactivity
with
N-benzylaniline
or
N-(trimethylsilyl)benzylamine
substrates,
have
been
investigated.
Isolated
intermediates
revealed
that
nature
C–H
activation
C–C
bond-forming
steps
in
alkyne
are
analogous
to
those
alkene
variant,
regardless
amine
substrate.
In
alkynes,
open
coordination
sphere
at
zirconium
center,
supported
by
bis(ureate)
ligand,
enables
neutral
protic
donors.
This
is
essential
for
promoting
catalytic
turnover
these
reactions.
Under
conditions,
dimethylamine
acts
as
a
proton
source
releasing
allylic
products
while
minimizing
formation
side
products.
Additionally,
we
identified
homoleptic
tetra(ureate)
complex
main
catalyst
decomposition
pathway
hydroaminoalkylation.
similar
structures
further
favored
when
employing
smaller
bis(urea)
proligands,
thus
explaining
poor
performance
some
ligands
catalysis.
However,
increasing
proligand
size
minimize
such
favors
isomerization
side-products
resulting
reduced
yields
desired
product.
study
provides
ligand
design
principles
guide
development
coordinatively
flexible
catalysts
achieve
systems
rely
upon
protonolysis
steps,
Chemistry - A European Journal,
Год журнала:
2024,
Номер
30(32)
Опубликована: Апрель 4, 2024
Abstract
Highly
regioselective
C−H
alkylation
reactions
of
tertiary
anilines
and
alkyl
amines
with
simple
alkenes
have
been
achieved
by
the
use
imidazolin‐2‐iminato
scandium
complexes.
This
protocol
provided
an
efficient
atom‐economical
route
to
structurally
diverse
amine
derivatives.
The
basic
ligand,
a
coordinating
THF
in
catalyst
substitution
alkene
substrates
were
found
switch
regioselectivity
presumably
due
generation
different
types
catalytically
active
species
or
formation
relatively
stable
intermediates.
On
basis
deuterium
labeling
experiments
KIE
experiments,
possible
catalytical
cycles
understand
reaction
mechanism
as
well
regioselectivity.
The Journal of Organic Chemistry,
Год журнала:
2022,
Номер
88(8), С. 4965 - 4974
Опубликована: Ноя. 30, 2022
In
this
Perspective,
the
use
of
methanol
and
ethanol
as
C1
C2
feedstocks
in
metal-catalyzed
C-C
couplings
to
π-unsaturated
pronucleophiles
via
hydrogen
auto-transfer
is
surveyed.
these
processes,
alcohol
oxidation
form
an
aldehyde
electrophile
balanced
by
reduction
hydrocarbon
a
transient
organometallic
nucleophile.
Mechanistically
related
reductive
paraformaldehyde
mediated
reductants
or
formic
acid
also
are
described.
These
processes
encompass
first
catalytic
enantioselective
and,
more
broadly,
illustrate
how
native
reducing
ability
alcohols
enable
departure
from
premetalated
reagents
carbonyl
addition.
ACS Catalysis,
Год журнала:
2024,
Номер
14(10), С. 8041 - 8049
Опубликована: Май 8, 2024
The
reason
for
the
site
selectivity
previously
reported
B(C6F5)3-catalyzed
C(sp3)–H
alkylation
of
tertiary
amines
with
electron-deficient
olefins
remains
a
mystery.
appears
to
be
governed
by
number
electron-withdrawing
groups
(EWGs)
on
olefin:
one
EWG
results
in
α-alkylation,
whereas
two
EWGs
(one
each
end
double
bond)
result
β-alkylation.
In
this
study,
we
solved
mystery
and
unlocked
pathway
β-alkylation
bearing
only
EWG.
Control
experiments
density
functional
theory
calculations
provided
detailed
picture
reaction
mechanism
both
α-
Furthermore,
demonstrated
broad
scope
reaction.
Inorganic Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Янв. 9, 2025
The
bipyridyl
tantalum
complex
(2,6-iPr2C6H3O)3Ta(bipy)
(2)
is
synthesized
by
the
reaction
of
(2,6-iPr2C6H3O)3TaCl2
(1)
and
2,2′-bipyridine
in
presence
excess
potassium
graphite
(KC8).
Complex
2
coordinates
readily
with
pyridine
4-(dimethylamino)pyridine
(dmap)
to
form
Lewis
base
adducts
(2,6-iPr2C6H3O)3Ta(bipy)(L)
(L
=
py
(3),
dmap
(4)),
it
exhibits
rich
redox
reactivity
toward
small
molecules:
(a)
single
electron
transfer
(SET)
occurs
upon
exposure
phenyl
sulfide
or
selenide
dimer,
giving
open-shell,
bipy-centered
radical
complexes
(2,6-iPr2C6H3O)3Ta(bipy•)(PhE)
(E
S
(5),
Se
(6)).
(b)
Regioselective
C–C
σ-bond
formation
via
coupling
observed
SET
aldehydes,
ketones,
imines
furnish
insertion
products
7–13,
namely,
sterically
more
crowded
benzophenone,
acetophenone,
2,6-dichlorobenzaldehyde,
benzophenone
imine
couple
C6
C6′
bipy
2,
respectively,
whereas
less
hindered
benzaldehyde,
cyclohexanone,
benzylideneaniline
C2
C2′
bipy,
respectively.
(c)
serves
as
a
synthon
for
(2,6-iPr2C6H3O)3Ta(III)
contact
diazene,
organic
azides,
1,4-diaza-1,3-diene
(conjugated)alkyne
derivatives,
which
imido/azido/hydrazido
(2,6-iPr2C6H3O)3Ta(═NPh)(bipy0)
(14),
(2,6-iPr2C6H3O)3Ta(═N3(2,6-iPr2C6H3))(bipy0)
(15),
(2,6-iPr2C6H3O)3Ta(═NSiMe3)(bipy0)
(16),
(2,6-iPr2C6H3O)3Ta(═N2CPh2)(bipy0)
(17);
σ2-enediamide
(2,6-iPr2C6H3O)3Ta(η2-N,N′-p-MeC6H4-DAD)
(18);
metallacyclopropenes
(2,6-iPr2C6H3O)3Ta(η2-C2Ph2)
(19)
(2,6-iPr2C6H3O)3Ta[η2-C(Ph)═C(C≡CPh)](bipy0)
(20)
are
formed
two-electron
process,
Journal of the American Chemical Society,
Год журнала:
2025,
Номер
unknown
Опубликована: Апрель 8, 2025
Catalyst
and
substrate
steric
electronic
features
that
influence
regioselectivity
in
hydroaminoalkylation
were
leveraged
to
develop
a
synthetic
approach
for
the
selective
synthesis
of
β-amino
acids.
An
situ
generated
tantalum-ureate
catalyst
was
used
prepare
18
γ-silylated
amines
up
93%
yield
from
internal
silylated
alkenes.
β-Amino
silane
regioisomer
production
rarely
observed,
making
this
work
one
few
examples
highly
regioselective
with
unsymmetric
These
γ-amino
silanes
converted
alcohols
modified
Tamao-Fleming
oxidation
strategy
followed
by
two
additional
steps
acids,
including
key
fragment
anticancer
drug
candidate
Ipatasertib.
Inorganic Chemistry,
Год журнала:
2023,
Номер
62(2), С. 979 - 988
Опубликована: Янв. 5, 2023
Benzylic
C(sp3)-H
alkylation
of
tertiary
anilines
with
alkenes
by
an
anilido-oxazoline-ligated
scandium
alkyl
catalyst
was
recently
reported
C-H
site
selectivity
and
alkene-dependent
regioselectivity.
Revealing
the
mechanism
origin
is
undoubtedly
great
importance
for
understanding
experimental
observations
developing
new
reactions.
Herein,
density
functional
theory
(DFT)
calculations
have
been
carried
out
on
model
reaction
Sc-catalyzed
benzylic
N,N-dimethyl-o-toluidine
allylbenzene.
The
generally
undergoes
generation
active
species,
alkene
insertion,
protonation
steps.
difference
distortion
energy
aniline
moiety
in
transition
states,
which
related
to
ring
size
forming
metallacycles,
accounts
activation.
activation
possessing
less
strained
five-membered
metallacycle
compared
ortho-C(sp2)-H
α-methyl
results
observed
experimentally.
Both
steric
electronic
factors
are
responsible
1,2-insertion
regioselectivity
alkyl-substituted
alkenes,
while
control
2,1-insertion
manner
vinylsilanes.
analysis
original
substrates
further
strengthens
These
help
us
obtain
mechanistic
expected
be
conducive
development
functionalization
ACS Organic & Inorganic Au,
Год журнала:
2022,
Номер
3(2), С. 74 - 91
Опубликована: Дек. 30, 2022
Organometallic
catalysis
is
a
powerful
strategy
in
chemical
synthesis,
especially
with
the
cheap
and
low
toxic
metals
based
on
green
chemistry
principle.
Thus,
selection
of
metal
particularly
important
to
plan
relevant
applicable
processes.
The
group
VB
have
been
subject
exciting
significant
advances
both
organic
inorganic
synthesis.
In
this
Review,
we
summarized
some
reports
from
recent
decades,
which
are
about
development
utilized
various
types
reactions,
such
as
oxidation,
reduction,
alkylation,
dealkylation,
polymerization,
aromatization,
protein
practical
water
splitting.