Advanced Synthesis & Catalysis,
Journal Year:
2021,
Volume and Issue:
363(13), P. 3372 - 3377
Published: May 22, 2021
Abstract
A
hydroxyl‐assisted,
organophotoredox/cobalt
dual
catalyzed
annulation
of
2‐propynolphenols
to
form
2‐hydroxymethyl‐benzo[
b
]furans
was
developed
by
employing
1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene
(4CzIPN)
as
photosensitizer
and
CoCl
2
(PPh
3
)
/5,5′‐dimethyl‐2,2′‐bipyridine
cobalt
catalytic
precursor.
Various
substrates
functional
groups
were
tolerated.
The
practical
applications
this
reaction
further
demonstrated
enlarged
gram‐scale
various
derivations
for
complex
heterocycles.
Primary
mechanistic
studies
suggested
the
involvement
cobalt‐hydride
mediated
hydrogen
atom
transfer
(HAT)
process.
magnified
image
Angewandte Chemie International Edition,
Journal Year:
2024,
Volume and Issue:
unknown
Published: June 19, 2024
Abstract
In
this
study,
we
unveil
a
novel
method
for
the
asymmetric
dearomatization
of
indoles
under
cobalt/photoredox
catalysis.
By
strategically
activating
C−H
bonds
amides
and
subsequent
migratory
insertion
π‐bonds
present
in
indole
as
reactive
partner,
achieve
syn
‐selective
tetrahydro‐5
H
‐indolo[2,3‐
c
]isoquinolin‐5‐one
derivatives
with
excellent
yields
enantiomeric
excesses
up
to
>99
%.
The
developed
operates
without
metal
oxidant,
relying
solely
on
oxygen
oxidant
employing
an
organic
dye
photocatalyst
irradiation.
Control
experiments
stoichiometric
studies
elucidate
reversible
nature
enantiodetermining
activation
step,
albeit
not
being
rate‐determining.
This
study
only
expands
horizon
cobalt‐catalyzed
bond
functionalization,
but
also
showcases
potential
synergy
between
cobalt
photoredox
catalysis
enabling
synthesis
complex
molecules.
European Journal of Organic Chemistry,
Journal Year:
2020,
Volume and Issue:
2020(7), P. 866 - 869
Published: Jan. 13, 2020
A
convenient
and
efficient
Co
III
‐catalyzed
cyclization
of
2‐arylquinazolinones
with
alkynes
is
described.
The
electron
donating
as
well
withdrawing
groups
also
halide
substituted
quinazolinones
are
compatible
this
reaction.
This
catalytic
reaction
highly
regioselective
unsymmetrical
alkynes.
possible
mechanism,
involves
a
formation
five‐membered
metallacycle
I
by
metal‐catalyzed
aromatic
C–H
bond
activation,
alkyne
insertion,
seven‐membered
intermediates
followed
reductive
elimination
to
give
final
product.
The Journal of Organic Chemistry,
Journal Year:
2020,
Volume and Issue:
85(6), P. 4482 - 4499
Published: March 2, 2020
A
new
method
for
cobalt-catalyzed
C(sp2)-H
functionalization
of
phenylglycinol
derivatives
with
terminal
and
internal
alkynes
directed
by
picolinamide
auxiliary
has
been
developed.
This
offers
an
efficient
highly
regioselective
route
the
synthesis
1-hydroxymethyltetrahydroisoquinolines.
The
reaction
employs
commercially
available
Co(II)
catalyst
in
presence
Mn(III)
cooxidant
oxygen
as
a
oxidant
proceeds
full
preservation
original
stereochemistry.
Advanced Synthesis & Catalysis,
Journal Year:
2021,
Volume and Issue:
363(13), P. 3372 - 3377
Published: May 22, 2021
Abstract
A
hydroxyl‐assisted,
organophotoredox/cobalt
dual
catalyzed
annulation
of
2‐propynolphenols
to
form
2‐hydroxymethyl‐benzo[
b
]furans
was
developed
by
employing
1,2,3,5‐tetrakis(carbazol‐9‐yl)‐4,6‐dicyanobenzene
(4CzIPN)
as
photosensitizer
and
CoCl
2
(PPh
3
)
/5,5′‐dimethyl‐2,2′‐bipyridine
cobalt
catalytic
precursor.
Various
substrates
functional
groups
were
tolerated.
The
practical
applications
this
reaction
further
demonstrated
enlarged
gram‐scale
various
derivations
for
complex
heterocycles.
Primary
mechanistic
studies
suggested
the
involvement
cobalt‐hydride
mediated
hydrogen
atom
transfer
(HAT)
process.
magnified
image
