Abstract
Pyrans
are
a
class
of
six‐membered
heterocyclic
rings
containing
five
carbon
atoms
and
one
oxygen
atom.
They
non‐aromatic
in
nature,
bearing
two
double
bonds
the
ring.
The
bond
position
distinguishes
pyran
isomers,
namely,
2
H
‐pyran
4
‐pyran.
When
saturated
sp
3
is
located
next
to
an
atom,
it
known
as
‐pyran,
when
at
4‐position
with
respect
In
1962,
by
thermal
breakdown
2‐acetoxy‐3,4‐dihydro‐2
‐pyrans
were
produced
for
first
time,
their
characteristics
explored.
Numerous
synthetic
methods
have
been
disclosed
over
time
owing
broad
applications
diverse
fields,
mainly
drug
design,
pharmaceuticals,
material
science.
this
review,
we
highlight
recent
advancements
toward
substituted
4‐pyranone,
2‐pyranones,
focusing
on
reports
published
from
2019
till
date,
which
play
important
roles
both
organic
synthesis
types
functional
molecules.
A
Ru-catalyzed
defluorinative
cyclization
of
polyfluoroalkyl
tetralones
has
been
developed
under
visible-light
irradiation
for
the
precise
assembly
γ-pyrones
featuring
α-perfluoroalkyl
and
β-fluorine
substituents.
Selective
functionalization
five
C(sp3)–F
bonds
at
three
carbon
sites
on
perfluoroalkyl
chain
provides
a
new
mode
utilizing
polyfluorides
as
versatile
synthons
to
access
difficult-to-obtain
heterocyclic
scaffolds.
Moreover,
sulfinate
salt
serves
dual
roles
an
oxygen
source
creating
carbonyl
group
defluorinating
promoter.
Organic Letters,
Год журнала:
2023,
Номер
25(12), С. 2139 - 2144
Опубликована: Март 22, 2023
The
three-component
reactions
of
enaminones,
α-diazo
esters/ketones,
and
t-butyl
nitrite
(TBN)
for
the
switchable
synthesis
isomeric
isoxazoles
have
been
realized.
catalysis
with
Cu(II)
salt
provides
3,4-disubsituted
via
[3
+
2]
cycloaddition.
On
other
hand,
Ag(I)
identical
substrates
leads
to
reversed
C3
C4
substitution
based
on
a
key
[2
1]
Organic Letters,
Год журнала:
2023,
Номер
25(40), С. 7298 - 7303
Опубликована: Окт. 3, 2023
An
unprecedented
protocol
for
a
Rh(III)-catalyzed
[3
+
2]
annulation
from
simple
and
readily
available
enaminones
iodonium
ylides
has
been
developed.
The
novel
strategy
allows
access
to
new
class
of
structurally
diverse
tetrahydro-indolones
with
high
efficiency
broad
substrate
scope.
In
addition,
this
transformation
represents
the
first
example
selective
alkenyl
C–H
bond
functionalization
enaminones.
Finally,
potential
applications
are
demonstrated
through
gram-scale
reaction
late-stage
modification.
Chemical Communications,
Год журнала:
2023,
Номер
59(27), С. 4036 - 4039
Опубликована: Янв. 1, 2023
The
synthesis
of
N-naphthyl
pyrazoles
has
been
realized
by
the
direct
three-component
reactions
enaminones,
aryl
hydrazine
hydrochlorides
and
internal
alkynes
via
Rh(III)
catalysis.
synthetic
employing
simple
substrates
lead
to
simultaneous
construction
dual
cyclic
moieties,
including
a
pyrazole
ring
phenyl
ring,
sequential
formation
two
C-N
three
C-C
bonds.
Organic Letters,
Год журнала:
2023,
Номер
25(39), С. 7214 - 7219
Опубликована: Сен. 26, 2023
A
novel
Rh(III)-catalyzed
cascade
alkenyl
C-H
activation/[3
+
2]
annulation/pinacol
rearrangement
reaction
of
enaminones
with
iodonium
ylides
has
been
developed.
This
methodology
provides
a
new
and
straightforward
synthetic
strategy
to
afford
highly
functionalized
2-spirocyclo-pyrrol-3-ones
in
satisfactory
yield
from
readily
available
starting
materials
under
mild
conditions.
Moreover,
gram-scale
reactions
further
derivatization
experiments
are
implemented
demonstrate
the
potential
utility
this
developed
approach.
By
means
of
simple
Rh
catalysis,
the
direct
activation
ortho-C-H
bond
in
aryl
enaminones
has
been
realized
with
enaminone
structure
as
a
traceless
directing
fragment.
The
products
resulting
from
C-H
alkenylation
and
further
annulation
via
intramolecular
addition
could
be
accessed
depending
upon
alkenes.
annulated
used
for
easy
synthesis
valuable
2-aza-fluorenones
one-pot
operation
by
employing
NH4OAc.
Chemistry - A European Journal,
Год журнала:
2023,
Номер
29(28)
Опубликована: Фев. 24, 2023
Using
benzylamines
as
the
C4
source
of
1,4-dihydropyridines
(1,4-DHPs),
a
Cu-catalyzed
oxidative
[1+2+1+2]
cascade
cyclization
for
synthesis
1,4-DHPs
was
firstly
developed.
A
broad
range
easily
available
N,N-dimethyl
enaminones
and
are
employed
smoothly
to
provide
diverse
with
high
efficiency.
This
method
is
performed
by
one-pot
C(sp3
)-H
bond
functionalization/C(sp3
)-N
cleavage/cyclization
strategy
form
simultaneously
two
)-C(sp2
)
bonds,
C(sp2
1,4-DHP
ring.
