Macromolecules,
Год журнала:
2024,
Номер
57(3), С. 991 - 1000
Опубликована: Янв. 24, 2024
Ladder
polymers
with
backbones
of
uninterrupted
ring-fused
units
have
attracted
academic
and
industrial
attention
for
decades
because
their
extended
π-conjugation
intrinsic
microporosity
possible
potential
applications
in
organic
optoelectronics
membrane
gas
separations.
We
report
herein
the
synthesis
characterization
a
new
series
oxepine-based
ladder/step-ladder
prepared
by
acid-promoted
intramolecular
aromatic
electrophilic
cyclization
reactions
on
alkyne-containing
poly(arylene
ether)
precursors.
In
contrast
to
more
common
annulations
that
produce
five-
six-membered
rings,
we
seven-membered
ring
can
be
regioselectively
quantitatively
generated
postpolymerization.
Model
compounds
repeating
also
been
synthesized,
X-ray
crystallographic
analysis
reveals
nonplanar
contorted
structure
is
present
polymers.
More
interestingly,
appear
display
photoinduced
planarization
8
π
electron
oxepine
driven
excited-state
stabilization
energy,
as
indicated
large
Stokes
shift.
Science,
Год журнала:
2021,
Номер
371(6536), С. 1338 - 1345
Опубликована: Март 25, 2021
Heteroaromatics
lured
into
cycloadditions
The
Diels-Alder
reaction
is
widely
used
to
produce
six-membered
carbon
rings
from
alkenes
and
dienes.
such
as
quinolines
resemble
dienes
in
principle,
but
practice
their
pairs
of
double
bonds
are
inert
toward
because
aromatic
stabilization.
Ma
et
al.
report
that
by
using
an
iridium
photosensitizer,
they
could
excite
related
azaarenes
triplet
states,
thereby
disrupting
the
aromaticity
enabling
intermolecular,
Diels-Alder–like
reactivity
(see
Perspective
Schmidt).
reactions
proceeded
exclusively
at
flanking
carbons
outside
nitrogen-containing
ring.
Science
,
this
issue
p.
1338
;
see
also
1313
Science,
Год журнала:
2023,
Номер
381(6653), С. 75 - 81
Опубликована: Июль 6, 2023
Skeletal
ring
enlargement
is
gaining
renewed
interest
in
synthetic
chemistry
and
has
recently
focused
on
insertion
of
one
or
two
atoms.
Strategies
for
heterocyclic
expansion
through
small-ring
remain
elusive,
although
they
would
lead
to
the
efficient
formation
bicyclic
products.
Here,
we
report
a
photoinduced
dearomative
thiophenes
by
bicyclo[1.1.0]butanes
produce
eight-membered
rings
under
mild
conditions.
The
value,
broad
functional-group
compatibility,
excellent
chemo-
regioselectivity
were
demonstrated
scope
evaluation
product
derivatization.
Experimental
computational
studies
point
toward
photoredox-induced
radical
pathway.
Helvetica Chimica Acta,
Год журнала:
2023,
Номер
106(3)
Опубликована: Янв. 13, 2023
Abstract
Skeletal
editing
involves
making
specific
point‐changes
to
the
core
of
a
molecule
through
selective
insertion,
deletion
or
exchange
atoms.
It
thus
represents
potentially
powerful
strategy
for
step‐economic
modification
complex
substrates
and
is
perfect
complement
methods
such
as
C−H
functionalization
that
target
molecular
periphery.
Given
their
ubiquity
in
biologically
active
compounds,
ability
perform
skeletal
on
–
therefore
interconvert
between
aromatic
heterocycles
especially
valuable.
This
review
summarizes
both
recent
key
historical
examples
applied
interconversion
rings;
we
anticipate
it
will
serve
highlight
not
only
innovative
enabling
nature
current
methods,
but
also
tremendous
opportunities
still
exist
field.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(4), С. 2845 - 2854
Опубликована: Янв. 18, 2024
In
this
report,
we
developed
a
unified
and
standardized
one-pot
sequence
that
converts
pyridine
derivatives
into
1,2-diazepines
by
inserting
nitrogen
atom.
This
skeletal
transformation
capitalizes
on
the
in
situ
generation
of
1-aminopyridinium
ylides,
which
rearrange
under
UV
light
irradiation.
A
thorough
evaluation
key
parameters
(wavelength,
reaction
conditions,
activating
agent)
allowed
us
to
elaborate
simple,
mild,
user-friendly
protocol.
The
model
was
extrapolated
more
than
40
examples,
including
drug
derivatives,
affording
unique
7-membered
structures.
Mechanistic
evidence
supports
transient
presence
diazanorcaradiene
species.
Finally,
pertinent
transformations
products,
ring
contraction
reactions
form
pyrazoles,
were
conducted
paved
way
broad
application
Journal of the American Chemical Society,
Год журнала:
2020,
Номер
143(2), С. 604 - 611
Опубликована: Дек. 31, 2020
Arene
dearomatization
is
a
straightforward
method
for
converting
an
aromatic
feedstock
into
functionalized
carbocycles.
Enantioselective
dearomatizations
of
chemically
inert
arenes,
however,
are
quite
limited
and
underexplored
relative
to
those
phenols
indoles.
We
developed
diazo-free
generation
silver-carbene
species
from
ynamide
applied
it
the
nonactivated
arenes.
Transiently
generated
norcaradiene
could
be
trapped
by
intermolecular
[4
+
2]
cycloaddition,
synthesizing
polycycles
with
five
consecutive
stereogenic
centers.
This
protocol
constitutes
first
highly
enantioselective
reaction
based
on
species.
Mechanistic
investigations
revealed
followed
two
different
classes
pericyclic
reactions,
as
well
origin
chemo-
enantioselectivity.
