A
single
step
method
for
the
production
of
unprotected
glycosyl
pyridinium
salts
has
been
developed
involving
treatment
sugar
with
a
pyridine,
triethylamine,
and
either
2‐chloro‐1,3‐dimethylimidazolinium
chloride
(DMC)
or
2‐chloro‐1,3‐dimethyl‐1
H‐benzimidazol‐3‐ium
(CDMBI)
as
an
activator,
in
aqueous
solution.
Reaction
efficiency
is
sensitive
to
steric
effects,
particular,
ortho
‐substitution
pyridine
ring
significantly
decreased
conversion
product;
para
well
tolerated.
Cyclic
voltammetry
reveals
that
possess
reduction
potentials
range
−0.9
−1.4
V
versus
standard
calomel
electrode,
which
are
modulated
by
electron
effects
substituents.
However,
pyridiniums
not
found
be
useful
precursors
radicals
under
photoredox
conditions.
Angewandte Chemie International Edition,
Год журнала:
2023,
Номер
62(38)
Опубликована: Июнь 7, 2023
Glycosyl
radical
functionalization
is
one
of
the
central
topics
in
synthetic
carbohydrate
chemistry.
Recent
advances
metal-catalyzed
cross-coupling
chemistry
and
metallaphotoredox
catalysis
provided
powerful
platforms
for
glycosyl
diversification.
In
particular,
discovery
new
precursors
conjunction
with
these
advanced
reaction
technologies
have
significantly
expanded
space
compound
synthesis.
this
Review,
we
highlight
most
recent
progress
area
starting
from
2021,
reports
included
will
be
categorized
based
on
different
types
better
clarity.
Accounts of Chemical Research,
Год журнала:
2023,
Номер
56(18), С. 2473 - 2488
Опубликована: Авг. 18, 2023
ConspectusThe
study
of
carbohydrates
has
emerged
as
a
crucial
research
area
in
various
disciplines
due
to
their
pivotal
roles
cellular
processes.
To
facilitate
in-depth
exploration
biological
functions,
chemical
glycosylation
reactions
that
allow
facile
access
glycoconjugates
broad
community
are
highly
needed.
In
classical
reactions,
glycosyl
donor
is
activated
by
an
acid
generate
reactive
electrophilic
intermediate,
which
subsequently
forms
glycosidic
bond
upon
reaction
with
nucleophilic
acceptor.
Such
ionic
pathway
been
the
mainstay
technique
for
glycoconjugate
synthesis
and
allowed
numerous
intricate
structures.
Nevertheless,
limitations
still
exist.
For
instance,
when
labile
donors
or
harsh
activating
conditions
required,
these
methods
show
limited
tolerance
hydroxyl
groups
abundant
on
sugar
rings.
addition,
achieving
good
stereocontrol
represents
another
longstanding
obstacle.
recent
years,
new
modes
activation
have
sought
tackle
above
challenges.We
noted
passing
through
intermediacy
radicals
via
cascade
single-electron
transfer
steps
possess
significant
but
underexplored
potential.
Progress
this
slow
large
part
dearth
handy
maneuver
radicals.
Most
existing
call
either
forcing
unstable/inconvenient
starting
materials.
order
better
exploit
power
radical
glycosylation,
we
developed
range
donors─namely,
sulfoxides,
sulfones,
sulfinates─that
bench
stable
can
be
readily
prepared
from
simple
These
form
under
mild
conditions.
Enabled
use
donors,
series
could
used
making
O-,
S-,
C-glycosides,
some
were
previously
difficult
access.
many
cases,
no
protecting
group
required.
As
illustration
potential
utility,
our
adopted
preparation
sugar–drug
conjugates,
sugar–DNA
glycopeptides,
even
glycoproteins.
While
most
cases
intrinsic
reactivity
intermediates
explored
axially
configured
products,
also
utilization
external,
delicate
reagents,
catalysts
override
such
innate
preference
achieve
catalyst-controlled
stereoselectivity.We
believe
enormous
inspire
development
novel
glycoside
synthesis.
Account,
highlight
design
principles
summarize
advancements
enabled
use,
provide
outlook
future
directions
field.
Chemical Science,
Год журнала:
2024,
Номер
15(4), С. 1204 - 1236
Опубликована: Янв. 1, 2024
This
review
article
highlights
the
diverse
ways
in
which
recent
developments
areas
of
photocatalysis
and
visible
light
photochemistry
are
impacting
synthetic
carbohydrate
chemistry.
Chemical Communications,
Год журнала:
2023,
Номер
59(55), С. 8564 - 8567
Опубликована: Янв. 1, 2023
C-Glycoside
analogs
of
naturally
occurring
glycoconjugates
are
useful
tools
for
chemical
biology
studies,
but
their
synthesis
usually
requires
protection
the
hydroxyl
groups
glycosyl
donors.
Here
we
report
protecting-group-free
and
photoredox-catalyzed
C-glycosylation
with
sulfinates
Michael
acceptors
via
Giese
radical
addition.
Synthetic
C-glycosides
play
a
crucial
role
in
molecular
biology
and
medicine.
With
the
surge
of
interest
demand
to
provide
efforts
with
sufficient
feedstock,
it
is
highly
significant
pursue
novel
methodologies
access
concise
efficient
manner.
Here,
we
disclose
an
attractive
strategy
that
diverges
itself
from
conventional
multistep
reaction
sequences
involving
manipulations
protecting
groups.
Widely
available
native
sugars
first
react
1,4-dihydropyridine
acids
via
site-selective
Mitsunobu
reaction,
converting
them
into
bench-stable
radical
precursors.
Under
visible-light-enabled
photoredox
catalysis
conditions,
resulting
glycosyl
radicals
undergo
C–C
bond
formation
reactions,
yielding
variety
excellent
stereoselectivity.
Our
method
demonstrates
good
tolerance
wide
range
functional
groups
has
been
successfully
applied
post-transformation
drug
molecules
preparation
C-glycosyl
amino
acids.
Organic Letters,
Год журнала:
2023,
Номер
26(14), С. 2686 - 2690
Опубликована: Апрель 26, 2023
Herein,
we
report
a
method
that
enables
the
synthesis
of
carbohydrate–DNA
conjugates
by
radical
addition.
Key
to
success
is
use
readily
available,
bench-stable,
and
unprotected
glycosyl
sulfinates
as
precursors
radicals.
The
redox
neutral
reaction
proceeds
under
mild
simple
conditions
tolerates
broad
substrate
scope.
A
small
library
was
prepared.
Organic Letters,
Год журнала:
2023,
Номер
25(33), С. 6099 - 6104
Опубликована: Авг. 14, 2023
A
visible-light-induced
glycoarylation
of
activated
olefins
has
been
accomplished.
Glycosyl
radicals
are
generated
via
radical
transfer
strategies
between
(TMS)3SiOH
and
glycosyl
bromides.
Subsequent
translocation
rapid
1,4-aryl
migration
form
β-sugar
amide
derivatives,
eight
types
sugars
compatible
with
this
reaction.
Further,
the
cascade
reaction
produced
a
quaternary
carbon
center
good
functional
group
adaptability
high
regioselectivity
in
mild
conditions.
ACS Catalysis,
Год журнала:
2024,
Номер
14(15), С. 11532 - 11544
Опубликована: Июль 19, 2024
Glycosyl
donor
activation
emerged
as
an
enabling
technology
for
anomeric
functionalization,
but
aimed
primarily
at
O-glycosylation.
In
contrast,
we
herein
disclose
mechanistically
distinct
electrochemical
glycosyl
bromide
activations
via
halogen-atom
transfer
and
C-glycosylation.
The
radical
addition
to
alkenes
led
C-alkyl
glycoside
synthesis
under
precious
metal-free
reaction
conditions
from
readily
available
bromides.
robustness
of
our
e-XAT
strategy
was
further
mirrored
by
C-aryl
C-acyl
glycosides
assembly
through
nickela-electrocatalysis.
Our
approach
provides
orthogonal
with
expedient
scope,
hence
representing
a
general
method
direct
C-glycosides
assembly.