Journal of the American Chemical Society,
Год журнала:
2021,
Номер
143(41), С. 17191 - 17199
Опубликована: Окт. 6, 2021
Radical-induced
1,2-metalate
rearrangements
of
boronate
complexes
are
an
emerging
and
promising
class
reactions
that
allow
multiple
new
bonds
to
be
formed
in
a
single,
tunable
reaction
step.
These
involve
the
addition
alkyl
radical,
typically
generated
from
iodide
under
photochemical
activation,
complex
produce
α-boryl
radical
intermediate.
From
this
there
two
plausible
pathways
can
trigger
product
forming
rearrangement:
iodine
atom
transfer
(IAT)
or
single
electron
(SET).
Previous
steady-state
techniques
have
struggled
differentiate
these
pathways.
Here
we
apply
state-of-the-art
time-resolved
infrared
absorption
spectroscopy
resolve
all
steps
cycle
by
mapping
production
consumption
reactive
intermediates
over
picosecond
millisecond
time
scales.
We
technique
recently
reported
involving
electron-deficient
strained
σ-bond
bicyclo[1.1.0]butyl
form
cyclobutyl
boronic
ester.
show
previously
proposed
SET
mechanism
does
not
adequately
account
for
observed
spectral
kinetic
data.
Instead,
demonstrate
IAT
is
preferred
pathway
likely
operative
other
type.
European Journal of Organic Chemistry,
Год журнала:
2022,
Номер
2022(9)
Опубликована: Янв. 12, 2022
Abstract
Organoboronates
are
synthetically
useful
and
highly
valuable
building
blocks
in
synthetic
medicinal
chemistry.
Two‐electron
reactions
allow
for
the
rapid
construction
of
organoboronates
via
nucleophilic
1,2‐boron
shift
boron
ate
complexes
or
MIDA‐mediated
1,2‐boryl
migration.
Radical
approaches
through
neutral
boronic
esters
have
been
demonstrated
to
be
feasible,
providing
complementary
methods
access
these
privileged
scaffolds.
In
this
Review,
recent
achievements
highlighted
future
opportunities
discussed,
with
an
emphasis
on
different
operative
modes
catalysis
reaction
pathways.
Journal of the American Chemical Society,
Год журнала:
2021,
Номер
143(25), С. 9320 - 9326
Опубликована: Июнь 20, 2021
Radical
aryl
migration
reactions
represent
a
unique
type
of
organic
transformations
that
involve
the
intramolecular
an
group
from
carbon
or
heteroatom
to
C-
heteroatom-centered
radical
through
spirocyclic
intermediate.
Various
elements,
including
N,
O,
Si,
P,
S,
Sn,
Ge,
and
Se,
have
been
reported
participate
in
migrations.
However,
boron
center
has
not
date.
In
this
communication,
1,5-aryl
boronate
complexes
is
presented.
C-radicals
readily
generated
addition
onto
alkenyl
are
shown
engage
provide
4-aryl-alkylboronic
esters.
As
can
be
situ
by
reaction
alkenylboronic
acid
esters
with
lithium
reagents,
moiety
varied,
providing
access
series
arylated
products
starting
same
ester
via
divergent
chemistry.
Reactions
proceed
high
diastereoselectivity
under
mild
conditions,
also
analogous
1,4-aryl
shifts
feasible.
The
suggested
mechanism
supported
DFT
calculations.
Journal of the American Chemical Society,
Год журнала:
2021,
Номер
143(41), С. 17191 - 17199
Опубликована: Окт. 6, 2021
Radical-induced
1,2-metalate
rearrangements
of
boronate
complexes
are
an
emerging
and
promising
class
reactions
that
allow
multiple
new
bonds
to
be
formed
in
a
single,
tunable
reaction
step.
These
involve
the
addition
alkyl
radical,
typically
generated
from
iodide
under
photochemical
activation,
complex
produce
α-boryl
radical
intermediate.
From
this
there
two
plausible
pathways
can
trigger
product
forming
rearrangement:
iodine
atom
transfer
(IAT)
or
single
electron
(SET).
Previous
steady-state
techniques
have
struggled
differentiate
these
pathways.
Here
we
apply
state-of-the-art
time-resolved
infrared
absorption
spectroscopy
resolve
all
steps
cycle
by
mapping
production
consumption
reactive
intermediates
over
picosecond
millisecond
time
scales.
We
technique
recently
reported
involving
electron-deficient
strained
σ-bond
bicyclo[1.1.0]butyl
form
cyclobutyl
boronic
ester.
show
previously
proposed
SET
mechanism
does
not
adequately
account
for
observed
spectral
kinetic
data.
Instead,
demonstrate
IAT
is
preferred
pathway
likely
operative
other
type.
