The
synthesis
of
quaternary
homoallylic
halides
and
trichloroacetates
from
cyclopropylcarbinols,
as
reported
by
Marek
in
2020
(J.
Am.
Chem.
Soc.
2020,
142,
5543-5548),
is
one
the
few
examples
stereospecific
nucleophilic
substitution
involving
chiral
bridged
carbocations.
However,
for
phenyl-substituted
substrates
stereoselectivity
reaction
poor
a
mixture
diastereomers
obtained.
In
order
to
understand
nature
intermediates
involved
this
transformation
explain
loss
selectivity
certain
substrates,
we
have
performed
Density
Functional
Theory
investigation
mechanism
at
DLPNO-CCSD(T)/Def2TZVPP
level
theory.
Our
results
indicate
that
cyclopropylcarbinyl
cations
are
stable
reaction,
while
bicyclobutonium
structures
high-energy
transition
such
not
involved,
regardless
pattern
on
substrate.
Instead,
multiple
rearrangement
pathways
been
located,
including
rotations
around
their
π-bonds
ring
openings
cations.
Importantly,
relative
energies
these
activation
barriers
reach
them
correlated
substituents.
While
direct
attack
cation
kinetically
favored
most
systems,
rearrangements
become
competitive
with
leading
through
rearranged
carbocation
intermediates.
As
such,
it
appears
reactions
depend
ability
access
structures,
which
guaranteed.
ACS Catalysis,
Journal Year:
2023,
Volume and Issue:
13(14), P. 9502 - 9508
Published: July 3, 2023
The
diastereoselective
synthesis
of
boron
and
carbon
vicinal
stereogenic
centers
is
a
great
challenge
in
current
synthetic
chemistry
due
to
the
paucity
efficient
strategies.
Herein,
Cu-catalyzed
diastereo-
enantioselective
B–H
bond
insertion
reaction
ene-yne-ketones
as
furyl-carbene
precursors
has
been
developed
using
chiral
bis(oxazolines)
(BOX)
ligand,
thus
furnishing
series
densely
functionalized
products
(42
examples)
bearing
both
high
enantioselectivity
diastereoselectivity
(up
99%
ee
>
20:1
dr)
with
good
yields
98%).
Journal of the American Chemical Society,
Journal Year:
2024,
Volume and Issue:
146(13), P. 8904 - 8914
Published: March 20, 2024
The
C(sp3)–H
bond
oxygenation
of
a
variety
cyclopropane
containing
hydrocarbons
with
hydrogen
peroxide
catalyzed
by
manganese
complexes
aminopyridine
tetradentate
ligands
was
carried
out.
Oxidations
were
performed
in
1,1,1,3,3,3-hexafluoro-2-propanol
(HFIP)
and
2,2,2-trifluoroethanol
(TFE)
using
different
catalysts
carboxylic
acid
co-ligands,
where
steric
electronic
properties
systematically
modified.
Functionalization
selectively
occurs
at
the
most
activated
C–H
bonds
that
are
α-
to
cyclopropane,
providing
access
carboxylate
or
2,2,2-trifluoroethanolate
transfer
products,
no
competition,
favorable
cases,
from
generally
dominant
hydroxylation
reaction.
formation
mixtures
unrearranged
rearranged
esters
(oxidation
HFIP
presence
acid)
ethers
TFE)
full
control
over
diastereoselectivity
observed,
confirming
involvement
delocalized
cationic
intermediates
these
transformations.
Despite
such
complex
mechanistic
scenario,
fine-tuning
catalyst
sterics
electronics
leveraging
on
relative
contribution
pathways
reaction
mechanism,
product
chemoselectivity
could
be
achieved.
Taken
together,
results
reported
herein
provide
powerful
catalytic
tools
rationally
manipulate
ligand
oxidations
hydrocarbons,
delivering
novel
products
good
yields
and,
some
outstanding
selectivities,
expanding
available
toolbox
for
development
synthetically
useful
functionalization
procedures.
Journal of the American Chemical Society,
Journal Year:
2022,
Volume and Issue:
144(36), P. 16298 - 16302
Published: Aug. 30, 2022
Herein,
we
present
the
formation
of
acyclic
frameworks
bearing
two
consecutive
stereocenters
either
tertiary
or
quaternary
nature
starting
from
easily
accessible
cyclopropenes.
This
holistic
approach
involves
a
regio-
and
diastereoselective
hydro-
carboborylation
substituted
cyclopropenyl
esters.
Formation
boronate
complexes
latter
via
addition
nucleophiles
subsequent
stereospecific
1,2-migration
with
carbon–carbon
bond
cleavage
delivered
title
compounds.
Angewandte Chemie International Edition,
Journal Year:
2022,
Volume and Issue:
62(3)
Published: Nov. 22, 2022
An
efficient
method
for
the
stereoselective
construction
of
tertiary
C-O
bonds
via
a
stereoinvertive
nucleophilic
substitution
at
quaternary
carbon
stereocenter
cyclopropyl
carbinol
derivatives
using
water,
alcohols
and
phenols
as
nucleophiles
has
been
developed.
This
reaction
proceeds
under
mild
conditions
tolerates
several
functional
groups,
providing
new
access
to
formation
highly
congested
homoallyl
ethers.
Organic Chemistry Frontiers,
Journal Year:
2023,
Volume and Issue:
10(9), P. 2346 - 2358
Published: Jan. 1, 2023
In
this
Review,
the
underrecognized
utilities
of
cyclopropylcarbinyl
cation
chemistry
are
summarized
in
cyclopropane
synthesis
and
skeletal
rearrangements,
their
applications
natural
product
total
highlighted.
The Journal of Organic Chemistry,
Journal Year:
2023,
Volume and Issue:
88(11), P. 6947 - 6954
Published: May 4, 2023
The
synthesis
of
quaternary
homoallylic
halides
and
trichloroacetates
from
cyclopropylcarbinols,
as
reported
by
Marek
(J.
Am.
Chem.
Soc.2020,
142,
5543-5548),
is
one
the
few
examples
stereospecific
nucleophilic
substitution
involving
chiral
bridged
carbocations.
However,
for
phenyl-substituted
substrates,
poor
specificity
observed
mixtures
diastereomers
are
obtained.
To
understand
nature
intermediates
involved
explain
loss
certain
we
have
performed
a
computational
investigation
reaction
mechanism
using
ωB97X-D
optimizations
DLPNO-CCSD(T)
energy
refinements.
Our
results
indicate
that
cyclopropylcarbinyl
cations
stable
in
this
reaction,
while
bicyclobutonium
structures
high-energy
transition
not
involved.
Instead,
multiple
rearrangement
pathways
were
located,
including
ring
openings
to
cations.
activation
barriers
required
reach
such
correlated
substituents;
direct
attack
on
kinetically
favored
most
systems,
rearrangements
become
competitive
with
leading
through
rearranged
carbocation
intermediates.
As
such,
reactions
depend
energies
access
their
corresponding
structures,
which
selectivity
guaranteed.
ACS Catalysis,
Journal Year:
2024,
Volume and Issue:
14(9), P. 7256 - 7266
Published: April 24, 2024
Stereoselective
synthesis
of
quaternary
stereocenters
represents
a
significant
challenge
in
organic
chemistry.
Herein,
we
describe
the
use
ene-reductases
OPR3
and
YqjM
for
efficient
asymmetric
chiral
4,4-disubstituted
2-cyclohexenones
via
desymmetrizing
hydrogenation
prochiral
2,5-cyclohexadienones.
This
transformation
breaks
symmetry
cyclohexadienone
substrates,
generating
valuable
with
high
enantioselectivities
(ee,
up
to
>99%).
The
mechanistic
causes
observed
were
investigated
both
experimentally
(stopped-flow
kinetics)
as
well
theoretically
(quantum
mechanics/molecular
mechanics
calculations).
synthetic
potential
resulting
enones
was
demonstrated
several
diversification
reactions
which
stereochemical
integrity
stereocenter
could
be
preserved.