Angewandte Chemie International Edition,
Journal Year:
2020,
Volume and Issue:
59(26), P. 10421 - 10425
Published: March 18, 2020
Abstract
An
atom‐economic
approach
that
has
an
unprecedented
high
selectivity
for
the
synthesis
of
lactic
acid
(LA)
based
on
a
catalytic
dehydrogenative
cross‐coupling
by
using
inexpensive
bulk
ethylene
glycol
and
methanol
is
described.
This
method
relies
utilization
novel
iridium
catalyst
bearing
three
N‐heterocyclic
carbenes
derived
from
1,3‐dimethylbenzimidazolium
salts,
exhibits
outstanding
activity
in
production
LA
[turnover
frequency
(TOF)
up
to
3660
h
−1
]
owing
elegant
metal–ligand
cooperation.
ACS Catalysis,
Journal Year:
2022,
Volume and Issue:
12(12), P. 6923 - 6933
Published: May 27, 2022
Urea
derivatives
have
significant
applications
in
the
synthesis
of
resin
precursors,
dyes,
agrochemicals,
and
pharmaceutical
drugs.
Furthermore,
polyureas
are
useful
plastics
with
coating,
adhesive,
biomedical
industries.
However,
conventional
methods
for
urea
involve
toxic
reagents
such
as
(di)isocyanates,
phosgene,
CO,
azides.
We
present
here
(poly)ureas
using
much
less
reagents─(di)amines
methanol─via
a
catalytic
dehydrogenative
coupling
process.
The
reaction
is
catalyzed
by
pincer
complex
an
earth-abundant
metal,
manganese,
liberates
H2
gas,
valuable
itself,
only
byproduct,
making
overall
process
highly
atom-economic.
A
broad
variety
symmetrical
unsymmetrical
been
synthesized
moderate
to
quantitative
yields
this
protocol.
Mechanistic
insights
also
provided
experiments
DFT
computation,
suggesting
that
proceeds
via
isocyanate
intermediate.
ACS Catalysis,
Journal Year:
2022,
Volume and Issue:
12(19), P. 12444 - 12457
Published: Sept. 28, 2022
Tandem
transformation
of
α,β-unsaturated
ketones
to
α-methylated
by
utilizing
methanol
as
both
the
hydrogen
and
C1
sources
is
reported
in
presence
a
phosphine-free
bis-N-heterocyclic
carbene-Mn(I)
(bis-NHC-Mn(I))
catalyst.
The
dehydrogenative
coupling
between
produces
corresponding
along
with
1
equiv
formaldehyde
water.
Among
different
bis-NHC-Mn(I)
complexes,
ethyl
wingtip-substituted
complex
triflate
counteranion
showed
highest
catalytic
activity.
This
system
was
highly
effective
for
reductive
methylation
wide
variety
substrates
including
aromatic,
heteroaromatic,
aliphatic
straight
chains
containing
ketones.
Notably,
this
methodology
led
synthesis
pharmaceutically
important
drug
molecules
such
eperisone
lanperisone.
Several
control
experiments,
kinetic
studies,
Hammett
density
functional
theory
(DFT)
calculations
were
carried
out
understand
tandem
process.
Organic Letters,
Journal Year:
2022,
Volume and Issue:
24(33), P. 6219 - 6223
Published: Aug. 12, 2022
A
mild,
environmentally
benign
approach
for
α-methylation
of
ketones
utilizing
methanol
as
the
C1
source
under
visible
light
has
been
developed.
The
reaction
conditions
were
favorable
a
wide
range
with
both
aromatic
and
aliphatic
backbones,
allowing
good-to-excellent
yields
respective
products.
tentative
mechanism
is
postulated
after
preliminary
mechanistic
kinetic
experiments.
Angewandte Chemie International Edition,
Journal Year:
2023,
Volume and Issue:
62(17)
Published: Feb. 27, 2023
Herein,
we
report
a
manganese-catalyzed
three-component
coupling
of
secondary
alcohols,
primary
alcohols
and
methanol
for
the
synthesis
β,β-methylated/alkylated
alcohols.
Using
our
method,
series
1-arylethanol,
benzyl
alcohol
derivatives,
undergo
sequential
efficiently
to
construct
assembled
with
high
chemoselectivity
in
moderate
good
yields.
Mechanistic
studies
suggest
that
reaction
proceeds
via
methylation
benzylated
intermediate
generate
final
product.
Angewandte Chemie International Edition,
Journal Year:
2020,
Volume and Issue:
59(26), P. 10421 - 10425
Published: March 18, 2020
Abstract
An
atom‐economic
approach
that
has
an
unprecedented
high
selectivity
for
the
synthesis
of
lactic
acid
(LA)
based
on
a
catalytic
dehydrogenative
cross‐coupling
by
using
inexpensive
bulk
ethylene
glycol
and
methanol
is
described.
This
method
relies
utilization
novel
iridium
catalyst
bearing
three
N‐heterocyclic
carbenes
derived
from
1,3‐dimethylbenzimidazolium
salts,
exhibits
outstanding
activity
in
production
LA
[turnover
frequency
(TOF)
up
to
3660
h
−1
]
owing
elegant
metal–ligand
cooperation.
