Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(22), С. 12214 - 12223
Опубликована: Май 24, 2023
Simple
aromatic
compounds
like
benzene
are
abundant
feedstocks,
for
which
the
preparation
of
derivatives
chiefly
begins
with
electrophilic
substitution
reactions
or,
less
frequently,
reductions.
Their
high
stability
makes
them
particularly
reluctant
to
participate
in
cycloadditions
under
ordinary
reaction
conditions.
Here,
we
demonstrate
exceptional
ability
1,3-diaza-2-azoniaallene
cations
undergo
formal
(3
+
2)
unactivated
below
room
temperature,
providing
thermally
stable
dearomatized
adducts
on
a
multi-gram
scale.
The
cycloaddition,
tolerates
polar
functional
groups,
activates
ring
toward
further
elaboration.
On
treatment
dienophiles,
cycloadducts
(4
cycloaddition–cycloreversion
cascade
yield
substituted
or
fused
arenes,
including
naphthalene
derivatives.
overall
sequence
results
transmutation
arenes
through
an
exchange
carbons:
two-carbon
fragment
from
original
is
replaced
another
incoming
dienophile,
introducing
unconventional
disconnection
synthesis
ubiquitous
building
blocks.
Applications
this
two-step
acenes,
isotopically
labeled
molecules,
and
medicinally
relevant
demonstrated.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(18)
Опубликована: Фев. 23, 2023
Herein,
a
general
strategy
for
chemo-
and
regioselective
1,2-reduction
of
chromium-bound
arenes
was
developed,
thus
providing
rapid
access
to
1,3-cyclohexadienes.
Selective
arene
activation
via
π-complexation
along
with
the
use
mild
hydride
Ph3
SiH
can
overcome
inherently
low
reactivity
π-bonds
while
tolerating
various
reduction-sensitive
functional
groups.
Its
versatility
further
enables
regiodivergent
deuteration.
Using
different
sequences
(non)deuterated
acid
reagents,
deuterated
positions
as
well
degrees
deuterium
incorporation
be
controlled
precisely,
which
leads
large
previously
inaccessible
chemical
space
1,3-cyclohexadiene
isotopologues.
A
reasonable
mechanism
proposed
based
on
intermediate
capture
control
experiments.
The
synthetic
value
this
selective
demonstrated
in
formal
total
synthesis
(±)-galanthamine
(±)-lycoramine.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(36)
Опубликована: Апрель 19, 2023
In
contrast
to
stable
and
natural
abundant
carbon-12,
the
synthesis
of
organic
molecules
with
carbon
(radio)isotopes
must
be
conceived
optimized
in
order
navigate
through
hurdles
radiochemical
requirements,
such
as
high
costs
starting
materials,
harsh
conditions
radioactive
waste
generation.
addition,
it
initiate
from
small
cohort
available
C-labeled
building
blocks.
For
long
time,
multi-step
approaches
have
represented
sole
patterns.
On
other
side,
development
chemical
reactions
based
on
reversible
cleavage
C-C
bonds
might
offer
new
opportunities
reshape
retrosynthetic
analysis
radiosynthesis.
This
review
aims
provide
a
short
survey
recently
emerged
isotope
exchange
technologies
that
effective
opportunity
for
late-stage
labeling.
At
present,
strategies
relied
use
primary
easily
accessible
radiolabeled
C1-building
blocks,
dioxide,
monoxide
cyanides,
while
activation
principles
been
thermal,
photocatalytic,
metal-catalyzed
biocatalytic
processes.
ACS Catalysis,
Год журнала:
2023,
Номер
13(7), С. 4042 - 4052
Опубликована: Март 16, 2023
The
development
of
ligands
and
the
elucidation
their
roles
in
catalytic
cycle
are
key
to
achieving
high
efficiency
selectivity
nondirected
transition-metal-catalyzed
C–H
functionalization.
In
particular,
careful
ligand
design
can
enable
functionalization
previously
inaccessible
substrate
positions,
which
lead
regiodivergent
transformations
common
reactants.
this
study,
a
series
pyrazolopyridone
(PzPyOH)
that
be
easily
prepared
single
step
was
developed
for
Pd-catalyzed
perdeuteration
meta-selective
alkenylation
arenes.
system,
2-pyridone
moiety
incorporated
function
as
an
internal
base,
facilitating
cleavage
rendering
activation
reversible,
even
at
challenging
sp2
bonds,
thus
enabling
perdeuteration.
addition,
reversible
bonds
implies
site
is
determined
during
migratory
insertion
reaction,
thereby
preferentially
functionalizing
meta-positions
rather
than
typically
more
reactive
ortho-
para-positions
anisole
derivatives.
Further,
electronic
structural
properties
pyrazole
provide
flexibility
binding
Pd,
facile
coordination
alkene
coupling
partner
alkenylation.
process,
hydrogen
bonding
between
pyridone
acetate
crucial
stabilize
intermediates,
allowing
different
types
modes,
including
L,L-
L,X-type
bidentate
monodentate
binding.
Kinetic
computational
studies
support
proposed
mechanisms
alkenylation,
findings
reveal
factors
functionalization,
will
useful
further
pyrazole-
pyridone-containing
transition
metal
catalysis.
Journal of the American Chemical Society,
Год журнала:
2023,
Номер
145(22), С. 12214 - 12223
Опубликована: Май 24, 2023
Simple
aromatic
compounds
like
benzene
are
abundant
feedstocks,
for
which
the
preparation
of
derivatives
chiefly
begins
with
electrophilic
substitution
reactions
or,
less
frequently,
reductions.
Their
high
stability
makes
them
particularly
reluctant
to
participate
in
cycloadditions
under
ordinary
reaction
conditions.
Here,
we
demonstrate
exceptional
ability
1,3-diaza-2-azoniaallene
cations
undergo
formal
(3
+
2)
unactivated
below
room
temperature,
providing
thermally
stable
dearomatized
adducts
on
a
multi-gram
scale.
The
cycloaddition,
tolerates
polar
functional
groups,
activates
ring
toward
further
elaboration.
On
treatment
dienophiles,
cycloadducts
(4
cycloaddition–cycloreversion
cascade
yield
substituted
or
fused
arenes,
including
naphthalene
derivatives.
overall
sequence
results
transmutation
arenes
through
an
exchange
carbons:
two-carbon
fragment
from
original
is
replaced
another
incoming
dienophile,
introducing
unconventional
disconnection
synthesis
ubiquitous
building
blocks.
Applications
this
two-step
acenes,
isotopically
labeled
molecules,
and
medicinally
relevant
demonstrated.