Chemistry - A European Journal,
Journal Year:
2022,
Volume and Issue:
29(3)
Published: Oct. 25, 2022
A
visible-light
organophotocatalytic
[2+2]
cycloaddition
of
electron-deficient
styrenes
is
described.
Photocatalytic
cycloadditions
are
typically
performed
with
electron-rich
styrene
derivatives
or
α,β-unsaturated
carbonyl
compounds,
and
transition-metal-based
catalysts.
We
have
discovered
that
an
organic
cyanoarene
photocatalyst
able
to
deliver
high-value
cyclobutane
products
bearing
aryl
substituents
in
good
yields.
range
tolerated,
both
homodimerisations
intramolecular
fused
bicyclic
systems
available
by
using
this
methodology.
Journal of the American Chemical Society,
Journal Year:
2022,
Volume and Issue:
144(44), P. 20207 - 20213
Published: Oct. 27, 2022
Synthesis
of
bicyclic
scaffolds
has
attracted
growing
interest
because
they
are
high
importance
in
modern
pharmaceutical
development.
Here
we
report
a
strategy
to
access
polysubstituted
2-oxabicyclo[2.1.1]hexanes
single
operation
from
readily
accessible
benzoylformate
esters
and
bicyclo[1.1.0]butanes
via
visible-light-induced
triplet
energy
transfer
catalysis.
The
process
is
proposed
involve
formal
[2π
+
2σ]
photocycloaddition/backbone
C-H
abstraction/aryl
group
migration
sequence.
A
diverse
range
(hetero)aryl
groups
successfully
underwent
the
backbone
(C2)
position
provide
previously
inaccessible
molecules,
ester
product
can
serve
as
handle
for
downstream
manipulation,
thus
offering
opportunities
rapidly
build
up
molecular
complexity
new
sp3-rich
chemical
space.
Journal of the American Chemical Society,
Journal Year:
2022,
Volume and Issue:
144(2), P. 963 - 976
Published: Jan. 5, 2022
Cyclometalated
Ir(III)
complexes
are
often
chosen
as
catalysts
for
challenging
photoredox
and
triplet-triplet-energy-transfer
(TTET)
catalyzed
reactions,
they
of
interest
upconversion
into
the
ultraviolet
spectral
range.
However,
triplet
energies
commonly
employed
photosensitizers
typically
limited
to
values
around
2.5-2.75
eV.
Here,
we
report
on
a
new
luminophore,
with
an
unusually
high
energy
near
3.0
eV
owing
modification
previously
reported
complex
isocyanoborato
ligands.
Compared
nonborylated
cyanido
precursor
complex,
introduction
B(C6F5)3
units
in
second
coordination
sphere
results
substantially
improved
photophysical
properties,
particular
luminescence
quantum
yield
(0.87)
long
excited-state
lifetime
(13.0
μs),
addition
energy.
These
favorable
properties
(including
good
long-term
photostability)
facilitate
exceptionally
organic
photoreactions
(sensitized)
triplet-triplet
annihilation
fluorescent
singlet
excited
state
beyond
4
eV,
deep
region.
The
photocatalyzes
sigmatropic
shift
[2
+
2]
cycloaddition
reactions
that
unattainable
common
transition
metal-based
photosensitizers.
In
presence
sacrificial
electron
donor,
it
furthermore
is
applicable
demanding
photoreductions,
including
dehalogenations,
detosylations,
degradation
lignin
model
substrate.
Our
study
demonstrates
how
rational
ligand
design
transition-metal
underexplored
effects)
can
be
used
enhance
their
thereby
broaden
application
potential
solar
conversion
synthetic
photochemistry.
Angewandte Chemie International Edition,
Journal Year:
2022,
Volume and Issue:
61(38)
Published: June 24, 2022
Recently
the
fruitful
merger
of
organoboron
chemistry
and
photocatalysis
has
come
to
forefront
organic
synthesis,
resulting
in
development
new
technologies
access
complex
(non)borylated
frameworks.
Central
success
this
combination
is
control
boron
hybridisation.
Contingent
on
photoactivation
mode,
as
its
neutral
planar
form
or
tetrahedral
boronate
can
be
used
regulate
reactivity.
This
Minireview
highlights
current
state
art
photocatalytic
processes
utilising
compounds,
paying
particular
attention
role
hybridisation
for
target
transformation.
Angewandte Chemie International Edition,
Journal Year:
2022,
Volume and Issue:
61(25)
Published: April 21, 2022
A
new
strategy
for
the
synthesis
of
highly
versatile
cyclobutylboronates
via
photosensitized
[2+2]-cycloaddition
alkenylboronates
and
alkenes
is
presented.
The
process
mechanistically
different
from
other
processes
in
that
energy
transfer
occurs
with
alkenylboronate
as
opposed
to
alkene.
This
allows
an
array
diverse
cyclobutylboronates.
conversion
these
adducts
compounds
well
their
utility
melicodenine
C
demonstrated.
The Journal of Organic Chemistry,
Journal Year:
2023,
Volume and Issue:
88(10), P. 6476 - 6488
Published: March 3, 2023
Four-membered
heterocycles
offer
exciting
potential
as
small
polar
motifs
in
medicinal
chemistry
but
require
further
methods
for
incorporation.
Photoredox
catalysis
is
a
powerful
method
the
mild
generation
of
alkyl
radicals
C–C
bond
formation.
The
effect
ring
strain
on
radical
reactivity
not
well
understood,
with
no
studies
that
address
this
question
systematically.
Examples
reactions
involve
benzylic
are
rare,
and
their
challenging
to
harness.
This
work
develops
functionalization
oxetanes
azetidines
using
visible
light
photoredox
prepare
3-aryl-3-alkyl
substituted
derivatives
assesses
influence
heterosubstitution
small-ring
radicals.
3-Aryl-3-carboxylic
acid
suitable
precursors
tertiary
oxetane/azetidine
which
undergo
conjugate
addition
into
activated
alkenes.
We
compare
oxetane
other
systems.
Computational
indicate
Giese
additions
unstrained
acrylates
reversible
result
low
yields
dimerization.
Benzylic
part
strained
ring,
however,
less
stable
more
π-delocalized,
decreasing
dimer
increasing
product
Oxetanes
show
high
due
Bent's
rule
rendering
irreversible.
