Organic Letters,
Journal Year:
2024,
Volume and Issue:
26(34), P. 7176 - 7180
Published: Aug. 16, 2024
Asymmetric
catalytic
reactions
rely
on
chiral
catalysts
that
induce
highly
ordered
transition
states
capable
of
imparting
stereoselectivity
in
the
bond-forming
step(s).
Productive
deviations
from
this
paradigm
are
rare
yet
hold
potential
for
accessing
different
stereoisomers
using
same
catalyst.
Here,
we
present
an
enantio-
and
diastereoselective
Michael
addition
β-keto
amides
to
nitroolefin
electrophiles
proceeding
via
unusual
scenario
where
kinetic
diastereocontrol
imparted
by
catalyst
may
be
overridden
crystallization
provide
complementary
stereoisomer
product.
Chemical Communications,
Journal Year:
2023,
Volume and Issue:
59(47), P. 7279 - 7282
Published: Jan. 1, 2023
In
this
study,
we
report
an
organocatalytic
formal
coupling
strategy
for
aryl-naphthoquinones
with
thiosugars
that
provides
straightforward
access
to
the
axially
chiral
naphthoquinone
thioglycoside
excellent
stereoselectivity.
Mechanistic
studies
revealed
key
role
of
H-bonding
in
stereochemical
recognition.
The
reaction
pathway
involves
atroposelective
addition,
followed
by
stereoretentive
oxidation
hydroquinone
intermediate.
The Journal of Organic Chemistry,
Journal Year:
2021,
Volume and Issue:
86(18), P. 12623 - 12643
Published: July 20, 2021
The
present
study
reports
an
asymmetric
organocatalytic
cascade
reaction
of
oxindole
derivates
with
α,β-unsaturated
aldehydes
efficiently
catalyzed
by
simple
chiral
secondary
amine.
Spirooxindole-fused
cyclopentanes
were
produced
in
excellent
isolated
yields
(up
to
98%)
enantiopurities
99%
ee)
and
moderate
high
diastereoselectivities.
synthetic
utility
the
protocol
was
exemplified
on
a
set
additional
transformations
corresponding
spiro
compounds.
In
addition,
showing
promising
biological
activity
selected
enantioenriched
products
accomplished.
The Journal of Organic Chemistry,
Journal Year:
2023,
Volume and Issue:
88(12), P. 7724 - 7735
Published: Jan. 27, 2023
The
present
study
reports
an
asymmetric
organocascade
reaction
of
oxindole-derived
alkenes
with
3-bromo-1-nitropropane
efficiently
catalyzed
by
the
bifunctional
catalyst.
Spirooxindole-fused
cyclopentanes
were
produced
in
moderate-to-good
isolated
yields
(15-69%)
excellent
stereochemical
outcomes.
synthetic
utility
protocol
was
exemplified
on
a
set
additional
transformations
corresponding
spirooxindole
compounds.
Organic Letters,
Journal Year:
2023,
Volume and Issue:
25(34), P. 6278 - 6283
Published: Aug. 18, 2023
A
synthesis
of
alstoscholarinoid
B
(1)
and
3β-acetoxy-11α-hydroxy-11(12
→
13)abeooleanan-12-al
(2)
has
been
accomplished
in
7-9
steps
10%-16%
overall
yield
from
oleanolic
acid.
This
featured
a
bioinspired
SmI2-mediated
reductive
aldol
reaction
to
establish
the
abeo-11(12
13)-oleanane
framework
both
1
2
retro-aldol/aldol/lactonization
cascade
fully
construct
skeleton
1.
Moreover,
investigation
also
sheds
light
on
potential
biogenesis
natural
products.
The Journal of Organic Chemistry,
Journal Year:
2024,
Volume and Issue:
89(9), P. 6027 - 6039
Published: April 17, 2024
In
this
study,
[1+2+2]
cyclization
of
tryptamine-derived
isocyanides
with
3-ylideneoxindoles
was
systematically
investigated.
A
series
structurally
complex
spiro-oxindole
derivatives
were
obtained.
Characteristic
dynamic
covalent
chemistry
observed
and
confirmed
by
experiments
density
functional
theory
calculation.
Through
the
regulation
solvent,
temperature,
time,
precise
stereodivergent
synthesis
spiro-oxindoles
achieved.
Abstract
We
describe
a
chiral
phosphoric
acid
(CPA)
catalyzed
asymmetric
[3+3]
cycloaddition
of
N
‐viny
oxindole
nitrones
with
2‐indolylmethanols
to
prepare
various
spirooxindole[1,2]oxazines
in
43–93%
yields
and
88:12–97:3
enantiomeric
ratios.
Experimental
results
revealed
that
the
addition
hexafluoroisopropanol
(HFIP)
played
important
roles
help
CPA
control
reaction
reactivity
enantioselectivity.
The
present
method
features
construction
tetrasubstituted
carbon
stereocenter
example
‐vinyl
cycloaddition.
The Journal of Organic Chemistry,
Journal Year:
2023,
Volume and Issue:
88(20), P. 14619 - 14633
Published: Oct. 4, 2023
Construction
of
pyrrolidinyl-spiroindoles
with
easily
available
starting
materials
has
attracted
considerable
attention
from
the
synthesis
community
and
is
in
great
demand.
Here,
we
describe
a
base-promoted
formal
(3
+
2)
cycloaddition
α-halohydroxamates
alkenyl-iminoindolines.
The
present
methodology
features
mild
reaction
conditions
broad
substrate
scope
up
to
99%
yield
excellent
diastereoselectivity.
versatility
this
approach
demonstrated
through
valuable
synthetic
transformations.
Preliminary
mechanistic
studies
shed
light
on
mechanism
process.
