European Journal of Organic Chemistry,
Journal Year:
2024,
Volume and Issue:
unknown
Published: Oct. 16, 2024
Abstract
A
squaramide
moiety
introduced
at
the
C‐4
position
of
proline
produced
an
organocatalyst
that
promoted
direct
asymmetric
aldol
addition
in
presence
water.
variety
adducts,
majorly
from
reaction
cyclohexanone
with
aldehydes,
were
obtained
yields
generally
range
53–99
%,
accompanied
by
71–99
%
ee
and
83
:
17
to
>99
1
diastereomeric
ratios.
An
desymmetrization
4‐alkyl
cyclohexanones
was
also
achieved
using
transformation.
The Chemical Record,
Journal Year:
2023,
Volume and Issue:
23(5)
Published: April 12, 2023
Abstract
The
development
of
procedures
useful
to
form
quaternary
stereocenters
stands
out
as
a
highly
challenging
task
in
asymmetric
synthesis.
With
the
arrival
organocatalysis,
different
activation
strategies
became
available
pursue
this
intriguing
target,
thus
leading
notable
advancements
area.
In
account,
our
achievements,
spanning
over
decade,
on
methodologies
access
novel
three‐,
five‐,
six‐membered
heterocycles,
including
spiro
compounds
bearing
stereocenters,
will
be
highlighted.
Michael
addition
reaction
has
been
often
exploited
trigger
cascade
reactions,
using
organocatalysts
mostly
derived
from
Cinchona
alkaloids,
and
operating
under
non‐covalent
reagents.
Further
manipulations
enantioenriched
attested
them
prepare
functionalized
building
blocks.
Organic Letters,
Journal Year:
2023,
Volume and Issue:
25(19), P. 3423 - 3428
Published: May 9, 2023
Simple,
clean
and
fast
photoconversion
of
aniline-derived
squaramides
was
achieved
by
flashlight
illumination.
UV
irradiation
enabled
the
photochemical
squaramide
ring-opening
to
generate
1,2-bisketenes,
which
DMSO
trapped
as
nucleophilic
oxidant.
The
only
photoproducts
isolated
were
3,4-arylamino
maleic
anhydrides,
present
conformational
preferences
very
different
from
those
their
parent
squaramides.
Similar
in
MeOH.
UV-mediated
time-dependent
anion
transport
inhibition
demonstrated,
establishing
a
new
approach
for
modulating
abilities
AD-squaramides.
A
four-step
synthesis
of
bifunctional,
noncovalent
organocatalysts
based
on
the
chiral
(1R,2R)-cyclohexane-1,2-diamine
scaffold
containing
a
1,2-benzenediamine
H-bond
donor
was
developed.
Nucleophilic
aromatic
substitution
2-fluoronitrobenzene
derivative
with
commercial
followed
by
selective
alkylation
primary
amino
group,
reduction
nitro
group
and
final
derivatization
i.e.
acylation,
sulfonation,
reductive
arylation,
leading
to
four
subtypes
organocatalysts.
All
new
compounds
were
fully
characterized.
The
prepared
(32
examples)
tested
in
Michael
addition
acetylacetone
trans-β-nitrostyrene,
yielding
product
incomplete
conversions
(up
93%)
enantioselectivities
up
41%
ee.
European Journal of Organic Chemistry,
Journal Year:
2024,
Volume and Issue:
unknown
Published: June 13, 2024
Abstract
Detailed
quantum‐chemical
calculations
have
been
carried
out
to
understand
both
the
origin
of
catalysis
in
urea‐catalyzed
nucleophilic
ring‐opening
nitrocyclopropanes
and
acceleration
induced
by
presence
an
internal
Lewis
acid
catalyst.
To
this
end,
mode
activation
these
ureas
is
quantitatively
analyzed
detail
means
Activation
Strain
Model
reactivity
combination
with
Energy
Decomposition
Analysis
method.
It
found
that
urea
further
enhances
interaction
between
reactants,
increasing
electrostatic
orbital
attractions,
which
translates
into
a
reduced
barrier.
This
insight
also
used
assess
impact
nature
on
transformation,
facilitating
rational
design
more
active
catalysts.
RSC Advances,
Journal Year:
2023,
Volume and Issue:
13(44), P. 31047 - 31058
Published: Jan. 1, 2023
Dehydroabietane-type
bifunctional
organocatalysts
derived
from
rosane-type
diterpenes
of
dehydroabietic
acid
(DHAA)
and
dehydroabietylamine
(DA)
have
been
utilized
in
a
wide
variety
highly
enantioselective
reactions.
Chemistry - A European Journal,
Journal Year:
2023,
Volume and Issue:
unknown
Published: Dec. 20, 2023
Abstract
Opposite
to
what
one
might
expect,
we
find
that
the
C=X
group
can
become
effectively
more,
not
less
,
electronegative
when
Pauling
electronegativity
of
atom
X
decreases
down
Groups
16,
15,
and
14
Periodic
Table.
Our
quantum‐chemical
analyses,
show
that,
why,
this
phenomenon
is
a
direct
consequence
increasing
size
group.
These
findings
be
applied
tuning
improving
hydrogen‐bond
donor
strength
amides
H
2
NC(=X)R
by
increasingly
withdrawing
density
from
NH
A
striking
example
NC(=SiR
)R
stronger
than
NC(=CR
)R.
Organic & Biomolecular Chemistry,
Journal Year:
2023,
Volume and Issue:
21(28), P. 5809 - 5826
Published: Jan. 1, 2023
Effective
synthesis
of
prolinamides
2-(2-aminocyclohexyl)phenols
has
been
accomplished.
The
novel
are
demonstrated
to
catalyze
the
direct
aldol
reaction
between
ketones
and
aldehydes
with
high
stereoselectivity,
thus
affording
up
99
:
1
anti/syn
diastereomeric
enantiomeric
ratio.
Experimental
results
as
well
computational
investigations
have
revealed
that
electrophile
(e.g.
aldehyde)
is
activated
by
dual
hydrogen
bonding
amide
NH
phenolic
OH
group
catalyst.
A
rather
large
spacing
H-bond
donor
groups
its
conformational
flexibility
remarkable
structural
features
most
enantioselective
Chemistry - A European Journal,
Journal Year:
2023,
Volume and Issue:
29(60)
Published: Aug. 2, 2023
Hydrogen
bonding
greatly
influences
rates
and
equilibrium
positions
of
chemical
reactions,
conformations,
sometimes
even
stereochemistry.
This
study
reports
on
tetranitrofluorenone
oximate,
a
novel
dye
capable
naked-eye
detection
hydrogen-bond
donating
species
(HBDs)
rapid
determination
H-bond
donation
strength
by
hypsochromic
shift
monitoring.
In
addition,
the
molecule
possesses
atropisomeric
M
P
configuration,
as
evidenced
in
solid
solution
state
studies
X-ray
diffraction
electronic
circular
dichroism
(ECD),
respectively.
latter
case,
enantiopure
bis-thioureas
were
most
effective
HBDs
to
promote
chiral
induction
(diastereoselective
recognition,
Pfeiffer
effect);
ECD
results
being
rationalized
time-dependent
density
functional
theory
(TDDFT)
calculations.
Based
these
experiments,
used
reagents
asymmetric
1,3-dipolar
cycloadditions
structurally-related
nitrones;
sensing
stereoinduction
between
oximate
serving
an
indirect
method
selection
HBD
for
synthesis.
Organic Letters,
Journal Year:
2023,
Volume and Issue:
25(48), P. 8590 - 8595
Published: Nov. 27, 2023
The
direct,
asymmetric
conjugate
addition
of
unactivated
α-branched
nitroalkanes
is
developed
based
on
the
combined
use
chiral
amine/ureidoaminal
bifunctional
catalysts
and
a
tunable
acrylate
template
to
provide
tertiary
nitrocompounds
in
55–80%
isolated
yields
high
enantioselectivity
(e.r.
up
96:4).
Elaboration
ketol
moiety
thus
obtained
adducts
allows
fast
entry
not
only
carboxylic
aldehyde
derivatives
but
also
nitrile
compounds
enantioenriched
5,5-disubstituted
γ-lactams.
