Stereoselective
chemical
glycosylation
reactions
are
pivotal
for
preparing
manifold
biologically
and
medically
important
compounds,
while
mechanisms
of
remain
obscure
largely
speculative.
Herein,
we
performed
DFT
calculations
to
delve
into
the
multifaceted
mechanistic
details
reactions,
including
equilibria
among
reactive
glycosyl
triflate
intermediates
in
solution,
stereoselectivity
imparting
protecting
groups,
solvent
effects,
base,
anomeric
effect.
Our
results
provided
theoretical
corroborations
2-OAc
neighbouring
group
participation
(NGP),
arming/disarming
effect,
coordination
theory
effect
on
stereochemistry,
influence
polarity
reaction
kinetics
spanning
SN1-SN2
continuum.
For
first
time,
existence
putative
contact-ion-pairs
(CIP)
oxocarbenium
anion
organic
solutions
was
theoretically
confirmed
with
identification
multiple
ground
state
structures
employing
an
implicit
model
based
density
(SMD).
Kinetics
nucleophilic
attack
glucosyl
triflates
by
simple
alcohol
acceptors
ethanol
(EtOH)
trifluoroethanol
(TFE),
complexed
2,4,6-tri-tert-butylpyrimidine
(TTBP)
were
explored,
revealing
essential
role
close
accompanying
base
rendering
glycosidic
bond
formation
thermodynamically
favorable.
work
deepens
comprehension
mechanism,
paving
way
rational
design
future
advancement
efficient
environmentally
friendly
stereoselective
reactions.
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.
Journal of the American Chemical Society,
Год журнала:
2024,
Номер
146(28), С. 18866 - 18872
Опубликована: Июль 5, 2024
C-Glycosides
are
important
structures
that
common
to
natural
products
and
pharmaceutical
agents.
Established
methods
for
their
synthesis
involve
the
reaction
of
an
activated
anomeric
carbon.
In
this
study,
we
report
a
conceptually
new
approach
involves
stereoselective
Ni-catalyzed
carboboration
glycals.
these
reactions,
not
only
is
C–C
bond
formed
at
carbon,
but
synthetically
useful
C–B
also
installed.
Upon
oxidation,
differentially
protected
C-glycosides
be
formed.
addition,
stereospecific
manipulation
leads
diverse
C-glycosides.
Finally,
application
method
in
established
C-glycosides,
such
as
C-glycosyl
amino
acids,
well
strategy
make
all
possible
diastereomers
C1
C2.
The Journal of Organic Chemistry,
Год журнала:
2023,
Номер
88(13), С. 8024 - 8033
Опубликована: Май 25, 2023
In
this
study,
we
have
successfully
applied
a
visible-light-promoted
desulfurization
method
to
the
synthesis
of
deoxysugars,
especially
1-deoxyglycose,
2,4-deoxyglycosides,
and
2-deoxyglycosides
with
exclusive
α-configuration.
Compared
reported
under
UV
light
(500
W
mercury
lamp),
visible
(20
blue
LED)
is
easy
operate
since
it
does
not
require
dedicated
photochemical
reactor,
occurs
very
mild
conditions,
able
avoid
many
side
reactions
that
often
occur
during
UV-induced
desulfurization.
The Journal of Organic Chemistry,
Год журнала:
2025,
Номер
unknown
Опубликована: Март 4, 2025
A
photocatalytic
approach
for
the
synthesis
of
difluorinated
glycoamino
acids
and
neoglycopeptides
from
bromodifluoroacetamides
sugar-derived
olefins
is
presented.
This
method
stands
out
because
its
simplicity,
atomic
economy,
mild
reaction
conditions,
allowing
compatibility
with
both
natural
unnatural
amino
peptides.
Additionally,
it
demonstrates
efficacy
across
a
variety
carbohydrates,
including
furanoses,
pyranoses,
pentose,
hexoses,
disaccharides,
accommodating
an
extensive
range
protecting
groups,
even
in
their
deprotected
forms.
Owing
to
the
toxic
reagent
and
high
temperature
required,
application
of
xanthate-based
radical
chemistry
has
been
limited.
To
address
these
challenges,
we
report
a
metal-
base-free,
photoinduced
strategy
for
stereoselective
C-alkyl
glycosylation
via
electron
donor-acceptor
(EDA)
complexes
glycosyl
xanthates
N-heterocyclic
carbene
(NHC)-BH3.
This
method
generates
radicals
under
mild
conditions,
affording
compatibility
with
wide
range
sugars
olefins
produce
glycosides
in
good
excellent
yields.
Mechanistic
studies
confirmed
formation
EDA
involvement
intermediates,
providing
insights
into
reaction
pathway.
The Journal of Organic Chemistry,
Год журнала:
2022,
Номер
87(19), С. 13178 - 13194
Опубликована: Сен. 12, 2022
The
intermolecular
C–O
coupling
reaction
of
1,4-quinones
with
exo-glycals
under
iron
hydride
hydrogen
atom
transfer
(HAT)
conditions
is
described.
This
method
provides
a
direct
and
regioselective
access
to
wide
range
phenolic
O-ketosides
related
biologically
relevant
natural
products
in
diastereomeric
ratios
up
>98:2
the
furanose
pyranose
series.
No
trace
corresponding
C-glycosylated
that
might
have
resulted
from
radical
alkylation
was
observed.
results
mechanistic
experiments
suggest
key
bond-forming
event
proceeds
through
an
oxidative
radical–polar
crossover
process
involving
single-electron
between
HAT-generated
glycosyl
electron-acceptor
quinone.
Synlett,
Год журнала:
2023,
Номер
34(16), С. 1866 - 1893
Опубликована: Май 16, 2023
Abstract
This
account
describes
our
recent
studies
in
the
field
of
glycomimetics.
Our
efforts
understanding
structural
basis
multivalent
effects
glycosidase
inhibition
have
led
to
decisive
mechanistic
insights
supported
by
X-ray
diffraction
analyses
and
discovery
multimeric
iminosugars
displaying
one
largest
binding
enhancements
reported
so
far
for
a
non-polymeric
enzyme
inhibitor.
Pushing
limits
inhibitory
effect
has
also
driven
progress
synthetic
methodology.
The
unexpected
observation
side
products
en
route
synthesis
targets
been
starting
point
several
new
methodologies,
including
metal-free
deoxygenation
alcohols
one-pot
double
thioglycosylation.
In
parallel
work
on
‘giant’
neoglycoclusters,
we
developed
access
original
constrained
glycomimetics
based
4-membered
ring
(‘square
sugars’).
Carbohydrates
with
quaternary
(pseudo)anomeric
position
were
synthesized
from
exo-glycals
through
catalytic
hydrogen
atom
transfer
novel
oxidative
radical-polar
crossover
process.
1
Introduction
2
Sweet
Giants
3
Multivalency
Spin-Offs
4
Curiosities
4.1
Square
Sugars
4.2
From
C,C-Glycosides
Formal
Glycosylation
Quinones
5
Conclusion
Green Synthesis and Catalysis,
Год журнала:
2024,
Номер
unknown
Опубликована: Март 1, 2024
Stereoselective
chemical
glycosylation
reactions
are
pivotal
for
preparing
manifold
biologically
and
medically
important
compounds,
while
mechanisms
of
remain
obscure
largely
speculative.
Herein,
we
performed
DFT
calculations
to
delve
into
the
multifaceted
mechanistic
details
reactions,
including
equilibria
among
reactive
glycosyl
triflate
intermediates
in
solution,
stereoselectivity
imparting
protecting
groups,
solvent
effects,
base,
anomeric
effect.
Our
results
provided
theoretical
corroborations
2-OAc
neighbouring
group
participation
(NGP),
arming/disarming
effect,
coordination
theory
effect
on
stereochemistry,
influence
polarity
reaction
kinetics
spanning
SN1-SN2
continuum.
For
first
time,
existence
putative
contact-ion-pairs
(CIP)
oxocarbenium
anion
organic
solutions
was
theoretically
confirmed
with
identification
multiple
ground
state
structures
employing
an
implicit
Solvation
Model
based
Density
(SMD).
Kinetics
nucleophilic
attack
model
glucosyl
triflates
by
simple
alcohol
acceptors
ethanol
(EtOH)
trifluoroethanol
(TFE),
complexed
2,4,6-tri-tert-butylpyrimidine
(TTBP)
were
explored,
revealing
essential
role
close
accompanying
base
rendering
glycosidic
bond
formation
thermodynamically
favorable.
work
deepens
comprehension
mechanism,
paving
way
rational
design
future
advancement
efficient
environmentally
friendly
stereoselective
reactions.
Organic Letters,
Год журнала:
2023,
Номер
25(32), С. 6046 - 6051
Опубликована: Авг. 9, 2023
Ferrier
rearrangement
on
glycals
is
an
efficient
tool
to
form
2,3-dideoxy
glycosides
that
provide
access
various
sugar
derivatives
through
olefin
functionalization.
The
classical
acid-mediated
transformation
delivers
the
α-O-glycosides
selectively.
In
this
protocol,
amides
obtained
from
amino
acids,
glycine
and
proline,
have
been
utilized
as
sustainable
β-directing
leaving
groups
glycal
substrates.
directing
facilitate
β-selective
rearrangements
for
hard
alcohol
nucleophiles
by
following
Pd(0)-catalyzed
Tsuji-Trost
inner
sphere
pathway.
