Chemistry - A European Journal,
Journal Year:
2020,
Volume and Issue:
27(8), P. 2628 - 2632
Published: Dec. 5, 2020
Abstract
Herein
we
describe
a
multiple
C−H
functionalization
reaction
of
carbazole
heterocycles
with
diazoalkanes.
We
show
that
gold
catalysts
play
distinct
role
in
enabling
to
introduce
up
six
carbene
fragments
onto
molecules
containing
units
or
link
into
single
molecule.
A
one‐pot
stepwise
approach
enables
the
introduction
two
different
allow
orthogonal
deprotection
and
straightforward
derivatization.
Chemistry - A European Journal,
Journal Year:
2020,
Volume and Issue:
27(4), P. 1270 - 1281
Published: Aug. 5, 2020
Abstract
Among
the
available
methods
to
increase
molecular
complexity,
sigmatropic
rearrangements
occupy
a
distinct
position
in
organic
synthesis.
Despite
being
known
for
over
century
rearrangement
reactions
of
ylides
via
carbene
transfer
reaction
have
only
recently
come
age.
Most
ylide
mediated
processes
involve
rupture
σ‐bond
and
formation
new
bond
between
π‐bond
negatively
charged
atom
followed
by
simultaneous
redistribution
π‐electrons.
This
minireview
describes
advances
this
research
area
made
recent
years,
which
now
opens
up
metal‐catalyzed
enantioselective
reactions,
metal‐free
photochemical
novel
pathways
that
can
be
accessed
intermediates.
Angewandte Chemie International Edition,
Journal Year:
2022,
Volume and Issue:
61(25)
Published: April 13, 2022
Stereoselective
cyclopropanation
reaction
of
alkenes
is
usually
achieved
by
metal
complexes
via
singlet-metal-carbene
intermediates.
However,
previous
transition-metal-catalyzed
with
acylsilanes
afforded
low
diastereoselectivity.
Herein,
we
report
the
first
visible-light-induced
transition-metal-free
terminal
trifluoroacetylsilanes
and
difluoroacetylsilanes.
Both
aromatic
aliphatic
as
well
electron-deficient
are
suitable
substrates
for
highly
cis-selective
[2+1]
cyclization
reaction.
A
combination
experimental
computational
studies
identified
triplet
carbenes
being
key
intermediates
in
this
transformation.
The
gram
scale
late-stage
functionalization
demonstrated
synthetic
potential
strategy.
Angewandte Chemie International Edition,
Journal Year:
2019,
Volume and Issue:
59(14), P. 5562 - 5566
Published: Dec. 27, 2019
Hexafluoroisopropanol
is
typically
considered
as
an
unreactive
solvent
and
not
a
reagent
in
organic
synthesis.
Herein,
we
report
on
mild
efficient
photochemical
reaction
of
aryl
diazoacetates
with
hexafluoroisopropanol
that
enables,
under
stoichiometric
conditions,
the
synthesis
fluorinated
ethers
excellent
yield.
Mechanistic
studies
indicate
there
preorganization
diazoalkane
acts
hydrogen-bonding
complex.
Only
after
photoexcitation
does
this
complex
undergo
protonation-substitution
to
product.
Investigations
applicability
transformation
show
broad
variety
acidic
alcohols
can
be
subjected
thus
demonstrate
feasibility
concept
for
O-H
functionalization
reactions
(54
examples,
up
98
%
yield).
Organic Letters,
Journal Year:
2019,
Volume and Issue:
21(21), P. 8814 - 8818
Published: Oct. 16, 2019
Cyclopropanation
reactions
of
carbenes
with
arenes
provide
a
straightforward
pathway
to
norcaradienes
or
cycloheptatrienes.
This
reaction
normally
requires
harsh
conditions
transition-metal
catalysts.
In
this
report,
we
describe
the
metal-free
visible-light
photolysis
aryl
diazoacetates
in
aromatic
solvents,
which
provides
access
norcaradiene
ring
system
highly
regio-
and
stereoselective
manner.
The
mild
approach
also
allow
chemoselective
cyclopropanation
substituted
without
competing
C-H
functionalization
reactions.
Chemical Science,
Journal Year:
2019,
Volume and Issue:
10(43), P. 10129 - 10134
Published: Jan. 1, 2019
We
have
shown
light
mediated
ring-expansion
reactions
of
4-membered
ring
heterocycles.
The
reaction
proceeds
via
a
diradical
mechanism
and
bond
length
play
key
role
in
the
stereodetermining
step.
Angewandte Chemie International Edition,
Journal Year:
2021,
Volume and Issue:
60(24), P. 13271 - 13279
Published: March 9, 2021
Controlling
the
reactivity
of
carbene
intermediates
is
a
key
parameter
in
development
selective
transfer
reactions
and
usually
achieved
by
metal
complexes
via
singlet
metal-carbene
intermediates.
In
this
combined
experimental
computational
studies,
we
show
that
free
diaryl
carbenes
can
be
controlled
electronic
properties
substituents
without
need
external
additives.
The
introduction
electron-donating
-withdrawing
groups
results
significant
perturbation
triplet
energy
splitting
intermediate
activation
energies
consecutive
reactions.
This
strategy
now
overcomes
long-standing
paradigm
allows
realization
highly
chemoselective
with
alkynes.
We
could
readily
accessed
photolysis
corresponding
diazo
compounds
these
undergo
cyclopropenation,
cascade,
or
C-H
functionalization
Experimental
theoretical
mechanistic
analyses
confirm
participation
different
spin
states
rationalize
for
observed
reactivity.
Chemistry - A European Journal,
Journal Year:
2019,
Volume and Issue:
26(12), P. 2586 - 2591
Published: Dec. 11, 2019
The
photolysis
of
diazoalkanes
is
a
timely
strategy
to
conduct
carbene-transfer
reactions
under
mild
and
metal-free
reaction
conditions,
has
developed
as
an
important
alternative
conventional
metal-catalyzed
reactions.
One
the
major
limitations
lies
within
rapidly
occurring
side
carbene
intermediate
with
remaining
diazoalkane
molecules
that
result
in
use
excess
partner
thus
impacts
on
efficiency.
Herein,
we
describe
protocol
takes
advantage
situ
generation
donor-acceptor
by
Bamford-Stevens
reaction.
Following
this
strategy,
concentration
can
be
minimized
reduce
unwanted
now
photochemical
transfer
stoichiometric
conditions.
We
have
explored
approach
C-H
N-H
functionalization
cyclopropanation
N-heterocycles
could
demonstrate
applicability
method
51
examples.
Angewandte Chemie International Edition,
Journal Year:
2021,
Volume and Issue:
61(4)
Published: Oct. 30, 2021
The
photolysis
of
diazoalkanes
to
conduct
singlet
carbene
transfer
reactions
colored
has
recently
attracted
significant
interest
in
organic
synthesis.
Herein,
we
describe
a
photocatalytic
approach
that
allows
the
access
triplet
intermediates
via
energy
highly
efficient
gem-difluoroolefination
with
α-trifluoromethyl
styrenes.
use
tertiary
amines
proved
pivotal
unlock
this
unusual
reaction
pathway
and
prevent
undesired
cyclopropanation
pathways.
amine
further
facilitates
ultimate
abstraction
fluoride
yield
gem-difluoroolefins
(43
examples,
up
88
%
yield),
which
is
supported
by
experimental
theoretical
mechanistic
studies.
We
explored
synthesis
method
broad
substrate
scope,
ranging
from
simple
olefins
heterocyclic
towards
decoration
pharmaceutically
relevant
building
blocks.
The Journal of Organic Chemistry,
Journal Year:
2019,
Volume and Issue:
84(17), P. 11316 - 11322
Published: Aug. 2, 2019
Metal-free
N-H
functionalization
reactions
represent
an
important
strategy
for
sustainable
C-N
coupling
reactions.
In
this
report,
we
describe
the
visible
light
photolysis
of
aryl
diazoacetates
in
presence
some
N-heterocycles
that
enables
mild,
metal-free
carbazole
and
azepine
heterocycles
(15
examples,
up
to
83%
yield).
