Angewandte Chemie,
Journal Year:
2023,
Volume and Issue:
135(34)
Published: June 27, 2023
Abstract
The
third
position
of
cyclopentadienyl
ring
a
monosubstituted
ferrocene
has
remained
as
an
inaccessible
chemical
space
for
direct
functionalization.
Until
recently,
functionalizing
the
C(3)‐position
while
bypassing
predominantly
active
C(2)‐position
is
most
challenging
task.
Herein,
we
report
distal
C−H
functionalization
ferrocenes
using
easily
removable
directing
group
with
precise
site‐selectivity,
under
Pd
II
/
mono‐
N
‐protected
amino‐acid
ligand
catalytic
system.
robust
synthetic
protocol
leads
to
synthesis
1,3‐derivatives
broad
scope
in
olefins
ferrocenyl
methylamine
moderate
good
yields
via
highly
strained
appended
12‐membered
palladacycle
intermediate.
Planar
chiral
ferrocenes
are
extensively
investigated
structures
in
asymmetric
catalysis,
materials
science,
and
medicinal
chemistry.
Although
the
synthetic
approaches
for
six-membered
fused
planar
well-established,
construction
of
a
seven-membered
ring
via
[4+3]
annulation
has
remained
unexplored
seems
to
be
challenging.
Herein,
an
efficient
rhodium-catalyzed
temperature-dependent
stereodivergent
reaction
been
developed
synthesis
novel
ferrocenylazepines
C-H
activation
substituted
ferrocene-p-tosylamides
with
allenes.
At
room
temperature,
Rh-catalyzed
selectively
offered
one
diastereomer
(>20:1
dr),
whereas,
at
60
ºC,
another
was
obtained
exclusively
dr).
Further,
presence
RhCpX
catalyst
(2
mol
%)
yielded
ferrocenyl
azepines
56%
yield
up
90:10
er.
Mechanistic
investigations
by
control
experiments,
iso-topic
labelling
study,
DFT
computation
suggested
that
proceeds
formation
σ-bonded
rhodacycle,
having
low
energy
due
less
steric
repulsion
between
phenyl
allene
Cp*(pentamethyl
cyclopentadienyl),
which
upon
reductive
elimination
kinetically
controlled
diastereomer.
Under
heating
(60
ºC)
conditions
base,
could
undergo
CH-allylic
isomerization
afford
completely
thermodynamic
diastereomer,
also
observed
experimentally.
Green Chemistry,
Journal Year:
2022,
Volume and Issue:
25(2), P. 554 - 559
Published: Dec. 24, 2022
Rh(
ii
)-catalyzed
C–H
carboxylation
of
ferrocene
derivatives
with
CO
2
was
developed.
The
first
example
-involved
asymmetric
achieved
moderate
enantioselectivity.
ACS Catalysis,
Journal Year:
2024,
Volume and Issue:
unknown, P. 17460 - 17468
Published: Nov. 12, 2024
Herein,
we
report
a
regio-and
stereoselective
distal
C–H
functionalization
protocol
for
ferrocenes,
leading
to
the
synthesis
of
planar
chiral
ferrocene-1,3-derivatives
by
Catellani-type
reaction.
The
successful
Pd(II)/norbornene
catalyst
combination
can
reach
inaccessible
reaction
site
ferrocene
and
accomplishes
selective
C(3)-arylation
ferrocenyl
methylamine.
ligand-controlled
synergistic
Pd/norbornene
metal–organic
cooperative
catalysis
under
aerobic
conditions
successfully
provides
an
array
in
moderate-to-good
yields
with
good
enantio-
diastereoselectivities.
A
unique
class
1,3-ligands,
including
PPFA-like
pincer
type
ligands
bearing
central
chirality,
has
been
synthesized
following
this
synthetic
methodology.
Angewandte Chemie,
Journal Year:
2023,
Volume and Issue:
135(34)
Published: June 27, 2023
Abstract
The
third
position
of
cyclopentadienyl
ring
a
monosubstituted
ferrocene
has
remained
as
an
inaccessible
chemical
space
for
direct
functionalization.
Until
recently,
functionalizing
the
C(3)‐position
while
bypassing
predominantly
active
C(2)‐position
is
most
challenging
task.
Herein,
we
report
distal
C−H
functionalization
ferrocenes
using
easily
removable
directing
group
with
precise
site‐selectivity,
under
Pd
II
/
mono‐
N
‐protected
amino‐acid
ligand
catalytic
system.
robust
synthetic
protocol
leads
to
synthesis
1,3‐derivatives
broad
scope
in
olefins
ferrocenyl
methylamine
moderate
good
yields
via
highly
strained
appended
12‐membered
palladacycle
intermediate.
