Formal Umpolung Addition of Phosphites to 2‐Azaaryl Ketones under Chiral Brønsted Base Catalysis: Enantioselective Protonation Utilizing [1,2]‐Phospha‐Brook Rearrangement
Chemistry - A European Journal,
Год журнала:
2022,
Номер
28(42)
Опубликована: Май 11, 2022
The
formal
enantioselective
umpolung
addition
of
dialkyl
phosphites
to
2-azaaryl
ketones
was
developed
under
Brønsted
base
catalysis.
reaction
involves
the
protonation
transient
α-oxygenated
(2-azaaryl)methyl
anion
generated
through
1,2-addition
phosphite
ketone
and
subsequent
[1,2]-phospha-Brook
rearrangement.
A
chiral
bis(guanidino)iminophosphorane
organosuperbase
efficiently
catalyzed
provide
enantio-enriched
phosphates
in
high
yields
with
good
enantioselectivities.
This
is
a
rare
example
catalytic
carbanions
other
than
enolates,
constructing
trisubstituted
stereogenic
center
α
2-azaarenes.
Язык: Английский
Extended Enolates: Versatile Intermediates for Asymmetric C‐H Functionalization via Noncovalent Catalysis
Chemistry - A European Journal,
Год журнала:
2021,
Номер
27(40), С. 10226 - 10246
Опубликована: Май 9, 2021
Catalyst-controlled
functionalization
of
unmodified
carbonyl
compounds
is
a
relevant
operation
in
organic
synthesis,
especially
when
high
levels
site-
and
stereoselectivity
can
be
attained.
This
objective
now
within
reach
for
some
subsets
enolizable
substrates
using
various
types
activation
mechanisms.
Recent
contributions
to
this
area
include
enantioselective
transformations
that
proceed
via
transiently
generated
noncovalent
di(tri)enolate-catalyst
coordination
species.
While
relatively
easier
form
than
simple
enolate
congeners,
di(tri)enolates
are
ambifunctional
nature
so
control
the
reaction
regioselectivity
becomes
an
issue.
Minireview
discusses
detail
other
problems,
how
approaches
based
on
metallic
metal
free
catalysts
have
been
developed
advance
field.
Язык: Английский
Enantioselective Organocatalytic Addition of Nitromethane to Trifluoromethyl Aryl Ketimines Promoted by Electron‐Rich Bifunctional Iminophosphoranes
Advanced Synthesis & Catalysis,
Год журнала:
2023,
Номер
365(7), С. 1093 - 1098
Опубликована: Март 2, 2023
Abstract
Thiourea‐based
iminophosphorane
(BIMP)
organocatalysts
featuring
SPhos‐
or
BIDIME
phosphine
units
have
been
developed
and
successfully
applied
in
the
asymmetric
addition
of
nitromethane
to
N
‐Boc‐protected
trifluoromethyl
aryl
ketimines.
α‐Trifluoromethyl
β‐nitroamines
were
obtained
40–82%
isolated
yields
80–95%
enantioselectivities.
A
careful
evaluation
catalytic
activity
BIMPs
indicates
that
catalysts
derived
from
combination
via
Staudinger
reaction
a
chiral
1,2‐amino
alcohol‐derived
thiourea‐organoazide
with
electron‐rich
phosphines,
promote
aza‐Henry
on
fluorinated
ketimines
highest
enantioselectivity,
leading
amine
tetrasubstituted
stereocenter
up
95%
ee.
The
was
performed
also
gram
scale,
without
loss
enantioselectivity.
magnified
image
Язык: Английский
Bi-functional and mono-component organocatalysts for the ring-opening alternating co-polymerisation of anhydride and epoxide
Catalysis Science & Technology,
Год журнала:
2023,
Номер
13(24), С. 7011 - 7021
Опубликована: Янв. 1, 2023
The
polyester
synthesis
from
anhydrides
and
epoxides
requires
their
strictly
alternating
incorporation
achieved
by
a
catalyst
that
is
capable
of
mediating
the
reactivity
carboxylate
alcohol
chain
ends.
Язык: Английский
Auto Tandem Catalysis: Asymmetric Vinylogous Cycloaddition/Kinetic Resolution Sequence for the Enantioselective Synthesis of Spiro‐Dihydropyranone from Benzylidene Meldrum's Acid
Advanced Synthesis & Catalysis,
Год журнала:
2021,
Номер
363(18), С. 4452 - 4458
Опубликована: Июль 28, 2021
Abstract
A
catalytic
enantioselective
vinylogous
domino
reaction
has
been
achieved
from
ketone‐derived
benzylidene
Meldrum's
acid
and
α‐ketolactones
to
provide
spirolactone
dihydropyranones
with
more
than
99%
ee.
An
Auto
Tandem
Catalysis
(ATC)
process
resulting
dual
complementary
role
of
(DHQ)
2
PHAL
organocatalyst
resulted
in
a
sequence
involving
an
asymmetric
formal
(4+2)
cycloaddition
the
subsequent
kinetic
resolution
operating
through
1,3‐prototropic
shift
leading
good
yields
(>50%)
high
selectivity.
magnified
image
Язык: Английский