ACS Catalysis,
Год журнала:
2019,
Номер
9(10), С. 9034 - 9044
Опубликована: Авг. 20, 2019
The
remote,
diastereoselective
hydroboration
of
2-
and
3-substituted
indenes
with
a
2,2′:6′,2″-terpyridine
cobalt
alkyl
precatalyst
is
described
that
maintains
high
regio-
stereoselectivity
independent
the
starting
position
alkene.
Several
1,2-
1,3-disubstituted
indanyl
boronate
esters
were
obtained
exclusive
(>20:1
dr)
selectivity
for
trans
diastereomer
including
synthetically
versatile,
stereodefined
diboron
derivatives.
Alkene
isomerization
by
putative
hydride
intermediate
precedes
carbon–boron
bond
formation,
leading
to
observed
regioselectivity
boron
incorporation
at
unsubstituted
C(sp3)–H
benzylic
site.
diastereoselectivity
transformation
maintained
alkene,
as
demonstrated
three
isomers
methyl-substituted
indene.
Deuterium-labeling
experiments
support
rapid
reversible
insertion
β-hydride
elimination
isomerize
3-methylindene
1-exo-methylene-indane,
accounting
isotopic
distribution
in
products.
Mechanistic
studies,
stoichiometric
experiments,
density
functional
theory
calculations,
kinetic
analysis,
mechanism
which
2,3-alkene
into
determines
both
catalytic
reaction.
Synthetic
applications
through
elaboration
products
several
examples
indanes,
important
carbocyclic
structural
motifs
pharmacological
bioactive
molecules.
Accounts of Chemical Research,
Год журнала:
2021,
Номер
54(11), С. 2701 - 2716
Опубликована: Май 20, 2021
ConspectusTransition
metal
catalyzed
asymmetric
hydrofunctionalization
of
readily
available
unsaturated
hydrocarbons
presents
one
the
most
straightforward
and
atom-economic
protocols
to
access
valuable
optically
active
products.
For
decades,
noble
transition
catalysts
have
laid
cornerstone
in
this
field,
on
account
their
superior
reactivity
selectivity.
In
recent
years,
from
an
economical
sustainable
standpoint,
first-row,
earth-abundant
metals
received
considerable
attention,
due
high
natural
reserves,
affordable
costs,
low
toxicity.
Meanwhile,
reactions
also
gained
much
interest
been
investigated
gradually.
However,
since
chiral
ligand
libraries
for
transition-metal
catalysis
are
limited
date,
development
highly
enantioselective
versions
remains
a
significant
challenge.This
Account
summarizes
our
efforts
developing
suitable
ligands
iron
cobalt
applications
(hydroboration
hydrosilylation)
alkenes
alkynes.
design,
we
envisioned
that
unsymmetric
NNN-tridentate
(UNT)
scaffolds
could
promote
these
transformations
with
metals.
Therefore,
several
types
UNT
were
designed
prepared
laboratory,
utilizing
amino
acids
as
sources.
very
beginning,
oxazoline
iminopyridine
(OIP)
proposed
through
rational
combination
nitrogen-containing
scaffolds.
After
systematic
survey
effects,
imine
moiety
rigid
OIP
was
replaced
by
conformationally
more
flexible
amine
unit,
leading
construction
reactive
aminoisopropylpyridine
(OAP)
ligands.
Subsequently,
imidazoline
(IIP)
thiazoline
(TIP)
altering
oxygen
atom
nitrogen
sulfur
linkers,
respectively.
To
further
expand
library,
other
tridentate
containing
twisted
pincer,
anionic,
nonrigid
backbone
synthesized,
including
iminophenyl
oxazolinyl
phenylamine
(IPOPA)
phenyl
picolinamide
(ImPPA).
The
efficacy
induction
has
demonstrated
sequential
alkynes,
which
exhibit
excellent
well
chemo-,
regio-,
stereoselectivity
broad
functional
group
tolerance.
Notably,
regio-
challenging
substrates,
such
1,1-disubstituted
aryl
terminal
aliphatic
alkenes,
achieved.
Furthermore,
isomerization/hydroboration
internal
alkynes
demonstrates
synthetic
power
catalytic
systems.
enantioenriched
products
obtained
methodologies
be
potentially
utilized
organic
synthesis,
medicinal
chemistry,
materials
science.
We
believe
continuous
field
would
beneficial
catalysis.
Chemical Society Reviews,
Год журнала:
2021,
Номер
50(23), С. 13129 - 13188
Опубликована: Янв. 1, 2021
We
provide
a
comprehensive
overview
of
transition
metal-catalysed
asymmetric
borylation
processes
to
construct
C–B,
C–C,
and
other
C–heteroatom
bonds
with
considerable
attention
devoted
the
reaction
modes
mechanisms
involved.
ACS Catalysis,
Год журнала:
2020,
Номер
11(1), С. 1 - 18
Опубликована: Дек. 10, 2020
Multi(boronate)
esters
have
been
attracting
increasing
attention
as
versatile
building
blocks
for
the
succinct
and
precise
synthesis
of
complex
molecules.
However,
there
are
a
limited
number
efficient
synthetic
procedures
available.
In
this
respect,
direct
multiboration
alkenes
alkynes
is
undoubtedly
an
ideal
route
their
synthesis.
During
past
30
years,
catalytic
systems
based
on
transition-metals,
organophosphines,
bases,
even
catalyst-free
systems,
with
heat
or
light
irradiation
straightforward
preparation
from
developed.
different
numbers
(up
to
4)
positional
relationships
adjacent
boron
moieties
were
obtained,
which
summarized
discussed
herein.
Journal of the American Chemical Society,
Год журнала:
2020,
Номер
142(42), С. 18213 - 18222
Опубликована: Сен. 23, 2020
We
report
the
incorporation
of
large
substituents
based
on
heavy
main-group
elements
that
are
atypical
in
ligand
architectures
to
enhance
dispersion
interactions
and,
thereby,
enantioselectivity.
Specifically,
we
prepared
chiral
biaryl
bisphosphine
(TMG-SYNPHOS)
containing
3,5-bis(trimethylgermanyl)phenyl
groups
phosphorus
and
applied
this
challenging
problem
enantioselective
hydrofunctionalization
reactions
1,1-disubtituted
alkenes.
Indeed,
TMG-SYNPHOS
forms
a
copper
complex
catalyzes
hydroboration
alkenes
with
high
levels
enantioselectivity,
even
when
two
both
primary
alkyl
groups.
In
addition,
catalysts
bearing
ligands
possessing
germanyl
were
much
more
active
for
than
one
derived
from
DTBM-SEGPHOS,
3,5-di-tert-butyl
widely
used
copper-catalyzed
hydrofunctionalization.
This
observation
led
identification
DTMGM-SEGPHOS,
3,5-bis(trimethylgermanyl)-4-methoxyphenyl
as
phosphorus,
new
highly
catalyst
unactivated
1,2-disubstituted
alkenes,
class
substrates
has
not
readily
undergone
previously.
Computational
studies
revealed
enantioselectivity
catalytic
efficiency
germanyl-substituted
is
higher
silyl
tert-butyl-substituted
analogues
because
attractive
between
bulky
trimethylgermanyl
ancillary
alkene
substrate
Pauli
repulsive
tended
decrease
Angewandte Chemie International Edition,
Год журнала:
2019,
Номер
58(28), С. 9448 - 9452
Опубликована: Май 6, 2019
A
series
of
in
situ
formed
alkenyl
diboronate
complexes
from
Grignard
reagents
(commercially
available
or
prepared
bromides
and
Mg)
with
B2
Pin2
(bis(pinacolato)diboron)
react
diverse
alkyl
halides
by
a
Ru
photocatalyst
to
give
various
gem-bis(boryl)alkanes.
Alkyl
radicals
add
efficiently
the
complexes,
adduct
radical
anions
undergo
radical-polar
crossover,
specifically,
1,2-boryl-anion
shift
boron
α-carbon
sp2
center.
This
transformation
shows
good
functional-group
compatibility
can
serve
as
powerful
synthetic
tool
for
late-stage
functionalization
complex
compounds.
Measurements
quantum
yield
reveal
that
radical-chain
mechanism
is
operative
which
diboronates
acts
reductive
quencher
excited
state
photocatalyst.
Nature Communications,
Год журнала:
2020,
Номер
11(1)
Опубликована: Фев. 7, 2020
Abstract
Double
hydroboration
of
dienes
is
the
addition
a
hydrogen
and
boryl
group
to
two
double
bonds
diene
molecule
represents
straightforward
effective
protocol
prepare
synthetically
versatile
bis(boryl)alkanes,
provided
that
this
reaction
occurs
selectively.
However,
can
potentially
yield
several
isomeric
organoboron
products,
it
still
remains
challenge
control
regioselectivity
reaction,
which
allows
selective
production
single
product,
in
particular,
for
broad
scope
dienes.
By
employing
readily
available
cobalt
catalyst,
here
we
show
yields
useful
gem
-bis(boryl)alkanes
with
excellent
regioselectivity.
In
addition,
encompasses
wide
range
conjugated
non-conjugated
Furthermore,
mechanistic
studies
indicate
cobalt-catalyzed
through
boryl-directed
chain-walking
alkenylboronates
generated
from
anti
-Markovnikov
1,2-hydroboration
1,n-diene.
Journal of the American Chemical Society,
Год журнала:
2020,
Номер
142(8), С. 3923 - 3930
Опубликована: Фев. 2, 2020
Unsymmetric
1,1-diboryl
alkenes
bearing
one
-[BPin]
(BPin
=
pinacolatoboryl)
and
-[BDan]
(BDan
1,8-diaminonaphthalatoboryl)
substituent
each
were
hydrogenated
in
high
yield
enantioselectivity
using
C1-symmetric
pyridine(diimine)
(PDI)
cobalt
complexes.
High
activities
stereoselectivities
observed
with
an
array
of
2-alkyl-,
2-aryl-,
2-boryl-substituted
alkenes,
giving
rise
to
enantioenriched
diborylalkane
building
blocks.
Systematic
study
substrate
effects
identified
competing
steric
electronic
demands
the
key
activating
role
boron
substituents,
whereby
sterically
unencumbered
boronates
such
as
-[BDan],
-[BCat]
(BCat
catecholatoboryl),
-[Beg]
(Beg
ethylene
glycolatoboryl)
promote
hydrogenation
trisubstituted
by
enabling
irreversible
α-boron-directed
insertion
pathways
achieve
otherwise
challenging
hydrogenations
alkenes.
Deuterium-labeling
studies
support
pathway
generating
a
chiral
intermediate
two
different
substituents
bound
same
carbon.
Journal of the American Chemical Society,
Год журнала:
2021,
Номер
143(33), С. 13124 - 13134
Опубликована: Авг. 12, 2021
Enantioenriched
1,1-silylboryl
alkanes
possess
silyl
and
boryl
groups
that
are
both
connected
to
the
same
stereogenic
carbon
center
at
well-defined
orientations.
As
these
chiral
multifunctionalized
compounds
potentially
offer
two
synthetic
handles,
they
highly
valued
building
blocks
in
asymmetric
synthesis
as
well
medicinal
chemistry.
Despite
potential
usefulness,
efficient
approaches
for
their
preparation
scarce.
Seeking
address
this
deficiency,
an
enantioselective
cobalt-catalyzed
hydrosilylation/hydroboration
cascade
of
terminal
alkynes
has
been
realized.
This
protocol
constitutes
impressive
case
chemo-,
regio-,
stereoselectivity
wherein
different
hydrofunctionalization
events
exquisitely
controlled
by
a
single
set
metal
catalyst
ligand,
operation
which
would
usually
require
separate
catalytic
systems.
Downstream
transformations
enantioenriched
1,1-silyboryl
led
various
valuable
compounds.
Mechanistic
studies
suggest
present
reaction
undergoes
regioselective
stereocontrolled
sequential
hydrosilylation
hydroboration
processes.
ACS Catalysis,
Год журнала:
2021,
Номер
11(16), С. 10660 - 10680
Опубликована: Авг. 12, 2021
Recent
years
have
witnessed
an
increase
in
the
popularity
of
α-boryl
organometallic
reagents
as
versatile
nucleophiles
asymmetric
synthesis.
These
compounds
been
adopted
chemo-
and
stereoselective
coupling
reactions
with
a
number
different
electrophiles.
The
resulting
enantioenriched
boronic
esters
can
be
applied
stereospecific
carbon-carbon
or
carbon-heteroatom
bond
construction
reactions,
enabling
two-step
strategy
for
complex
structures
high
efficiency
functional
group
compatibility.
Due
to
these
reasons,
tremendous
effort
has
devoted
preparation
enantiomerically
enriched
development
related
racemic
prochiral
materials.
In
this
review,
we
describe
enantio-
diastereoselective
that
involve
starting
materials
products
showcase
their
synthetic
utility.
Journal of the American Chemical Society,
Год журнала:
2022,
Номер
144(33), С. 15333 - 15338
Опубликована: Авг. 11, 2022
Selective
defluoroborylation
and
asymmetric
hydroboration
reactions
of
fluoroalkyl-substituted
terminal
alkenes
with
pinacolborane
(HBpin)
have
been
developed
cobalt
catalysts
generated
from
Co(acac)2
bisphosphine
ligands.
A
variety
undergo
this
enantioselective
hydroboration,
affording
the
corresponding
chiral
alkylboronates
containing
stereogenic
carbon
centers
high
enantioselectivity
(up
to
98%
ee).
This
provides
a
versatile
foundation
for
synthesis
organofluorine
compounds
centers.