ACS Catalysis,
Journal Year:
2021,
Volume and Issue:
11(16), P. 10279 - 10287
Published: Aug. 3, 2021
Stereo-
and
regioselective
glycosidation
is
still
a
great
challenge
in
carbohydrate
chemistry.
Among
the
tremendous
endeavors
this
area,
acid–base
catalysis,
available
to
O-glycosyl
trichloroacetimidate
activation,
of
particular
interest.
It
features
an
alternative
pathway
initiated
by
sequential
binding
between
catalyst
glycosyl
acceptor
then
with
donor.
Through
formation
catalyst–acceptor
adduct,
increased
proton
acidity
oxygen
nucleophilicity
are
reached,
thus
enforcing
donor
activation
concomitant
transfer.
As
reaction
takes
place
via
SN2-type
transition
state,
essentially
stereoselectivity
granted.
Platinum(IV)
chloride
ideal
regard;
it
weak
Lewis
acid,
yet
possesses
high
affinity
hydroxy
group
due
its
ligand-binding
capacity,
affording
from
α-configurated
product
predominantly
β-configuration.
In
addition,
capacity
platinum(IV)
bidentate
ligation
another
advantage,
as
enhances
differences
groups,
permitting
glycosidation,
observed
for
various
1,2-cis-,
1,3-,
1,2-trans-diol
1,2,3-triol
moieties
present
acceptors.
This
observation
found
application
efficient
saponin
natural
synthesis.
Chemical Science,
Journal Year:
2022,
Volume and Issue:
13(19), P. 5659 - 5666
Published: Jan. 1, 2022
General
photoactivation
of
EDA
complexes
between
arylsulfonium
salts
and
1,4-diazabicyclo[2.2.2]octane
was
discovered.
This
practical
mode
enables
the
generation
aryl
radicals
for
C–H
functionalization
arenes.
Science,
Journal Year:
2023,
Volume and Issue:
382(6673), P. 928 - 935
Published: Nov. 23, 2023
Despite
their
importance
in
life
and
material
sciences,
the
efficient
construction
of
stereo-defined
glycosides
remains
a
challenge.
Studies
carbohydrate
functions
would
be
advanced
if
glycosylation
methods
were
as
reliable
modular
palladium
(Pd)-catalyzed
cross-coupling.
However,
Pd-catalysis
excels
forming
sp
2
-hybridized
carbon
centers
whereas
mostly
builds
3
C–O
linkages.
We
report
platform
through
Pd-catalyzed
S
N
displacement
from
phenols
toward
bench-stable,
aryl-iodide–containing
glycosyl
sulfides.
The
key
Pd(II)
oxidative
addition
intermediate
diverges
an
arylating
agent
(Csp
electrophile)
to
glycosylating
electrophile).
This
method
inherits
many
merits
cross-coupling
reactions,
including
operational
simplicity
functional
group
tolerance.
It
preserves
mechanism
for
various
substrates
is
amenable
late-stage
commercial
drugs
natural
products.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(6), P. 4112 - 4122
Published: Jan. 16, 2024
Lipoarabinomannan
(LAM)
from
the
Mycobacterium
tuberculosis
cell
envelope
represents
important
targets
for
development
of
new
therapeutic
agents
against
tuberculosis,
which
is
a
deadly
disease
that
has
plagued
mankind
long
time.
However,
accessibility
long,
branched,
and
complex
lipoarabinomannan
over
100-mer
remains
long-standing
challenge.
Herein,
we
report
modular
synthesis
mannose-capped
101-mer
M.
wall
using
one-pot
assembly
strategy
on
basis
glycosyl
ortho-(1-phenylvinyl)benzoates
(PVB),
not
only
accelerates
but
also
precludes
potential
problems
associated
with
glycosylation
thioglycosides.
Shorter
sequences
including
18-mer,
19-mer,
27-mer
are
synthesized
in-depth
structure–activity
relationship
biological
studies.
Current
synthetic
routes
highlight
following
features:
(1)
streamlined
various
linear
branched
glycans
orthogonal
combination
N-phenyltrifluoroacetimidates,
ortho-alkynylbenzoates,
PVB;
(2)
highly
stereoselective
construction
10
1,2-cis-arabinofuranosyl
linkages
5-O-(2-quinolinecarbonyl)-directing
1,2-cis-arabinofuranosylation
via
hydrogen-bond-mediated
aglycone
delivery
strategy;
(3)
convergent
[(18
+
19)
×
2
27]
LAM
polysaccharide.
The
present
work
demonstrates
this
can
streamline
chemical
polysaccharides.
Organic Letters,
Journal Year:
2022,
Volume and Issue:
24(8), P. 1587 - 1592
Published: Jan. 26, 2022
An
open-air
palladium-catalyzed
O-glycosylation
was
developed
using
glycals
and
arylboronic
acids
with
base
additives
at
ambient
conditions.
The
novel
approach
enabled
facile
access
to
various
O-glycosides
in
high
yields,
exclusive
1,4-cis-stereoselectivity
tolerating
reactive
hydroxyl/amino
groups.
Mechanistic
studies
indicated
that
chemo-/stereoselectivity
arose
from
the
coordination
between
palladium
phenols
generated
situ
by
oxidizing
acids,
followed
an
intramolecular
attack.
Isotope-labeling
experiments
revealed
oxygen
of
O-glycosidic
bonds
came
O2.
Angewandte Chemie International Edition,
Journal Year:
2023,
Volume and Issue:
62(42)
Published: Aug. 17, 2023
Here
we
report
a
simple
and
general
method
to
achieve
fully
unprotected,
stereoselective
glycosylation
of
carboxylic
acids,
employing
bench-stable
allyl
glycosyl
sulfones
as
donors.
Running
the
reaction
under
basic
conditions
was
crucial
for
efficiencies
selectivities.
Both
donor
activation
stage
glycosidic
bond
forming
process
are
compatible
with
free
hydroxyl
groups,
thereby
allowing
use
unprotected
This
transformation
is
stereoconvergent,
occurs
mild
metal-free
at
ambient
temperature
visible
light
(455
nm)
irradiation,
displays
remarkable
scope
respect
both
partners.
Many
natural
products
commercial
drugs,
including
an
acid
derived
from
complex
anticancer
agent
taxol,
were
efficiently
glycosylated.
Experimental
studies
provide
insights
into
origin
stereochemical
outcome.
Chemical Science,
Journal Year:
2024,
Volume and Issue:
15(17), P. 6552 - 6561
Published: Jan. 1, 2024
Collective
synthesis
of
mucin-related
tumor
associated
carbohydrate
antigens
has
been
achieved
via
this
new
α-glycosylation
method
with
GalN
3
donors,
which
features
mild
conditions,
broad
substrate
scope,
high
yields
and
stereoselectivities.
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(25), P. 17446 - 17455
Published: June 11, 2024
Polysaccharides
from
a
medicinal
fungus
Ganoderma
sinense
represent
important
and
adjunctive
therapeutic
agents
for
treating
various
diseases,
including
leucopenia
hematopoietic
injury.
However,
the
synthetic
accessibility
to
long,
branched,
complicated
carbohydrates
chains
polysaccharides
remains
challenging
task
in
chemical
synthesis.
Here,
we
report
modular
synthesis
of
nona-decasaccharide
motif
polysaccharide
GSPB70-S
with
diverse
biological
activities
first
time
through
one-pot
stereoselective
glycosylation
strategy
on
basis
glycosyl
ortho-(1-phenyvinyl)benzoates,
which
not
only
sped
up
but
also
reduced
waste
avoided
aglycones
transfer
issues
inherent
thioglycosides.
The
route
highlights
following
key
steps:
(1)
preactivation-based
highly
constructions
several
1,2-cis-glycosidic
linkages,
three
α-d-GlcN-(1
→
4)
linkages
one
α-d-Gal-(1
bond
via
reagent
N-methyl-N-phenylformamide
modulation;
(2)
orthogonal
assembly
1,2-trans-glycosidic
linear
branched
glycans
fragments
by
strategic
combinations
N-phenyltrifluoroacetimidates,
ortho-alkynylbenzoates,
ortho-(1-phenyvinyl)benzoates;
(3)
final
[1
×
4
+
15]
Yu
efficient
target.
Additionally,
shorter
sequences
4-mer,
5-mer,
6-mer
are
prepared
structure–activity
relationship
studies.
present
work
shows
that
this
can
offer
reliable
effective
means
streamline
complex
many
bonds.
The Journal of Organic Chemistry,
Journal Year:
2020,
Volume and Issue:
85(17), P. 11280 - 11296
Published: Aug. 5, 2020
This
report
describes
the
first
example
of
palladium-catalyzed
ortho-C–H
glycosylation/ipso-alkenylation
aryl
iodides,
and
easily
accessible
glycosyl
chlorides
are
used
as
a
glycosylation
reagent.
The
reaction
is
compatible
with
functional
groups
substrates,
series
C-aryl
glycosides
have
been
synthesized
in
good
to
excellent
yield
diastereoselectivity.
It
found
that
cheap
5-norbornene-2-carbonitrile
transient
mediator
can
effectively
promote
this
reaction.
In
addition,
ipso-arylation
cyanation
were
also
realized
by
strategy.
