Frontiers in Chemistry,
Journal Year:
2022,
Volume and Issue:
10
Published: Sept. 13, 2022
A
metal-free
catalytic
approach
for
the
remote
C6-functionalization
of
2,3-disubstituted
indoles
has
been
developed.
In
presence
amounts
Brønsted
acid,
β,γ-unsaturated
α-ketoesters
react
with
at
C6
position
selectively.
Under
mild
reaction
conditions,
a
range
C6-functionalized
were
prepared
good
yields
and
excellent
regioselectivity.
This
methodology
provides
concise
efficient
route
synthesis
indole
derivatives.
Abstract
We
developed
a
temperature‐controlled
intermolecular
dearomative
[5+1]
spiroannulation
and
[5+2]
cyclization
of
indoles
with
enynones,
smoothly
delivering
variety
spiroindolenines
dihydrocyclohepta[
b
]indolones
under
40
°C
80
°C,
respectively.
A
three‐step
cascade
reaction
was
also
realized
by
using
OTBS
or
NHBoc
containing
enynones
in
the
indole
identical
condition.
And
novel
valuable
highly‐oriented
three‐dimensional
indole‐based
tetracyclic
scaffold
produced
high
yields
excellent
diastereoselectivities.
Additionally,
various
spiroindolines
spirooxindoles
were
facilely
through
simple
operations.
This
highly
efficient
domino‐reaction
represents
an
emblematic
method
for
preparation
polycycles
pathway.
Frontiers in Chemistry,
Journal Year:
2022,
Volume and Issue:
10
Published: Sept. 13, 2022
A
metal-free
catalytic
approach
for
the
remote
C6-functionalization
of
2,3-disubstituted
indoles
has
been
developed.
In
presence
amounts
Brønsted
acid,
β,γ-unsaturated
α-ketoesters
react
with
at
C6
position
selectively.
Under
mild
reaction
conditions,
a
range
C6-functionalized
were
prepared
good
yields
and
excellent
regioselectivity.
This
methodology
provides
concise
efficient
route
synthesis
indole
derivatives.
