FUNCTIONAL GROUP OXIDATION USING SODIUM

Tee&m
Vol. 43. No. 8. pp. 1753 to 1758. 1987
Printedin Cheat Britain.
oMMom/87
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FUNCTIONALGROUP OXIDATION USING SODIUM PERBORATE’
ALEXANDERMcKILLOP* and JONATHANA. TARBIN
School
of
Chemical
Norwich,
Sciences,
Norfolk,
University
of East
NR4 7TJ, England.
Anglia,
(Received in (IS.4 28 January 1987)
Abstract
- Sodium perborate
in acetic
acid
is an effective
reagent
for the oxidation
of anllines
to nitroarenes
and of
It is also an
sulphides
to either
sulphoxides
or sulphones.
excellent
reagent
for
the oxidative
deprotection
of ketone
dlmethylhydrazones.
Baeyer-Villiger
oxidation
of ketones
can
be carried
out with sodium perborate
in either
trifluoroacetic
acid
and
acid
or
acetic
acid/trifluoroacetic
mixtures,
substituted
phenols
are
hydroquinones
and certain
highly
smoothly
converted
into quinones.
Sodium
500,000
perborate
tons
per
as
detergents,
is
antiseptic
little
of
handled
used
of
the
of
formula
for
given
as
salt
the
to
of
the
increase
as
hydration
decreases.
We have
selective
the
easily
be scaled
nature,
problems,
it
types
Oxidation
could
of
of
Anilines
corresponding
ease
well
hydrogen
it
compounds,4*5
so
has
held
peroxide
been
a number
and for
feu applications
widely
only
of
the
to
oxl-
organic
misconception
and sodium
very
easily
that
borate.
The
to
of
water
of
given
safe
prove
_/OH
O-O’/B\OB
HG,,//o-0
known
/
HO
utility
of
of
The various
cheapness
handling,
to
sodium
and report
oxidation
the
2Na+ O-6B20
1
synthesis
conditions.
of
are
the
oxidising
controlled
up and,
non-toxic
these
the
and
aware
in
bleaching,
has been
epoxidatlon
been
is
organic
reaction
fibre
there
(over
oxygen”
crystalline
for
has
the potential
for
for
mild
of
for
low yield
to azo
to
“active
as we are
the
there
part
l-4).
and the
examined
reagent
very
-
amount
oxidant
useful
(n
reagent
in
chlorine
stable,
chemical
of
frequently
structure
be 1,7
As far
anilines
industrial
surprisingly,
this
for
a mixture
is
of
Rather
That
least
merely
the
but
determined
under
at
NaB03.nH20
example,
ability
is
of
acids.6
scale
as a source
forms
of
a-dlketones,2
oxidation
due
perborate
various
synthesis.
of
the
may be
large
primarily
applications
alkenylboronic
chemistry
sodium
for
used
to
organic
cleavage
qulnones,3
dation
to
cheap,
is
and mouthuash.
possible
oxidant
for
very
an alternative
and as a mild
study
a
annum) which
of
reagent
it,is
of
oxidations
the
of
tetrahydrate
indeed
a variety
and absence
be the
perborate
that
functional
described
perborate,
groups
below
together
of
effluent
choice
for
or
at
as a
an extremely
with
can
its
by-product
least
some of
transformations.
Anilines
to Yitroarenes
containing
nitroarenes
electron-withdrawing
in good
to
excellent
1753
groups
yield
are
smoothly
on treatment
oxidlsed
uith
to
the
excess
of
A. McKnm~
1754
sodium
perborate.
50-55OC
uas
signalled
for
to
be
by separation
a variety
those
The reaction
found
of
obtained
peracetic
acetic
of
anilines
with
acid,
is
the
best
optimum
carried
out
in Table
reagents
commonly
pertrifluoroacetic
acid
sodium
I.
acetic
Completion
crystalline
given
in glacial
temperature.
colourless,
are
other
and J. A. Teem-
These
employed
and 905
of
borate,
are
for
this
and
is
and yield
at least
hydrogen
acid,
reaction
data
comparable
oxidation,
peroxide
to
such
in
as
trifluoro-
acid.
Table
Oxidation
of
Anillnes
I
to Nitroarenes
with
Sodium Perborate/Acetic
ArNH2
ArN02
Yield,
esb
ArNO,
Yield,
-Ar
Acid
ArNH2
5
m2
-Ar
Yield,
$
92
4-02NC6H4
85
70
4-ci c6~4
2,6-C1$6Hj
a7
2-NCC6Hq
a9
55
2,4,6-C13C6H2
a2
4-NCC6H4
91
2-02N-4-CH3OC6H3
3-Cp3C6H4
63
a0
4-RrC6H4
2-02NC6H4
aa
76
4-CH3COC6H4
4-C2H500cC6H4
73
84
4-CF3C6H4
86
47
4-CH3C+,
4-CR3OC6H4
4-CR3CONHC6H4
2
No attempt
b
Refers
Anilines
under
extent
depending
tarry
but
generally
substrate,
of
little
practical
accessible
by
quinoline
and
a
were
respectively.
Attempted
material,
extend
the
to
oxidation
highly
cyclohexylamine
gave
as
tars,
As
group.
of
(66%)
oxidation
of
could
which
are
Interestingly,
unaffected
under
2-aminothiazole
and
anilines
investigated
nitrosobenzene
and
to
gave,
which
products
all
moderate
compounds
methods.
were
nitro-
a variable
contaminated
these
expected,
nitrobenzene
aniline
always
as
were
to
to
therefore,
3-aminopyridfne,
products
a mixture
are
are,
nitration
of t-butylamine
polar
oxidised
occurs
N-aminophthalimide
hydroxyl
to
products
nltroarenes
direct
black
oxidised
also
also
consequence
but
to
phenolic
smoothly
Attempts
unsuccessful.
starting
oxidised
crude
pure
conditions,
were
contained
and the
of
products.
are
overoxidation
yields
reaction
azobenxene
groups
but
The
readily
a-aminoquinoline
or redistilled
electron-donating
on the
is
yields.
recrystallised
conditions,
4-aminopyridine,
above
uhich
pure,
same
this
more
and
the
the
materials.
(45-70s)
2-
to
containing
arenes
by
was made to optimise
aliphatic
be
(92%)
amlnes
in addition
not
and
azoxybenzene
to
were
unchanged
identified.
nltrocyclohexane
while
was a minor
component.
Oxidation
of
Sulphides
A wide
variety
either
sulphoxides
effect
either
oxidation
excess
to
ot
present
in Table
*
the
oxidant
were obtained
or
using
or
an
in good
II.
sulphone
Clearly
in each
transformation.
perborate
50%
(5
eq),
Moreover,
is
to
of
those
sulphides
of
the
the
effective
both
used
were
an
to
for
sodium
smoothly
a small
sulphoxldes
sulphone
data
Por the
amino
to
found
When only
Representative
particularly
sulphides
been
methanolic
solution,
a few percent
oxidation
of
also
yield.
acid
by chromatography.
perborate
has
aqueous
excellent
in acetic
case
oxidation
conditions
using
in
the
perborate
identical
was employed
removed
sodium
of
for
sodium
sulphones
yield;
and was easily
and
Under
excess
eq)
available
alternatlvely
corresponding
(1.1
or Sulphones
is
sulphones,
anilines,
and
oxidised
reagents
transiormation.
of
hydroxide,
to Suiphoxides
of
was also
are
given
sulphide
group
and
a
1755
Functionalgroupoxidation
.
sulphide
of
can be readily
oxidant
in acetic
2 by acetylation
acid
gave
sodium
acid
gave 2 in 81s
followed
the
by oxidation
sulphone
namely
examined,
2
the
perborate
treatment
accomplished;
in
in acetic
aold
at 50-55OC
of
Sulphides
of
gave
Table
Oxidation
of
the
which
the
with
disulphone
Yield,
8 equivalents
with
n-C4Hg
93
99
t-C4Hg
72
97
CH3
73
94
CH3
75
91
CH3
‘gH5
a5
98
71
98
No attempt
Refers
was made to optimise
to pure,
a
:I
2
-
Sodium
Yield,
t-C4Hg
1
of
Sulphon&@b
5
n-C4H9
5
in
5 in 89s yield.
and Sulphones
Sulphoxid&lb
R-S-R’
‘gH5
amino group
Acid
Sulphide
4-ClC6H4
an excess
II
to Sulphoxides
Perborate/Acetic
‘gH5
4-CH9C6h4
with
excess
of sodium perborate
in acetic
Only one example of a disulphide
was
oxidation
5,
Sor example,
Protection
yield.
with
93% yield.
,3-dithiane
1
of 2.
$
yields.
recrystalllsed
or redistilled
products.
*02
NH2
81x
“ZCg3
=gQ
3
(CH3CO)20
NECOCB3
1
=I
a
93%
Sal3
“ZcH3
4
n
n
89%
sxii
‘6’5
02SxS02
3
‘sH5
Oxidation
Ketones
of
to Esters
Baeyer-Villlger
conditions
only
as
ulth
acetate
in
Sl$
oxidation
benzoate.
of
for
of
OF ketones
the
oxidation
which
have
uith
of
at
4-Hethoxyacetophenone,
yield
sodium
high
for
ketones
aptitude.
equivalents
required
oxidation
employed
aromatic
migratory
CH3
s
s
yield
under
the
standard
perborate.
conversions,
cyolohexanone
to
Data for typical
ketone
For
sodium
anilines
least
for
one
ketones,
and trifluoroacetic
caprolactone
oxidations
group
example,
oonditions
other
perborate
under
and sulphldes
of
gives
outlined
more acidic
aoid
the
is
same
effective
relatively
high
4-methoxyphenyl
above,
and with
conditions
was necessary
benzophenone
and of
are summarised in Table
to
III.
3
were
for
phenyl
1756
A. MCKILLOP and I. A. TAREIN
Table III
Oxidation Of Ketones to Esters with Sodium Perborate/Acetic Acidg
Ketone
Solvent
C6H5COCH3
C6H5CH$OCH3
4-CH3C6H4COCH3
4-CH30C6H4COCH3
4-C6HgC6HqCOCH3
4-RrC6H4COCH3
C6H5COC6H5
Cyclohexanone
Ester
501 CF3COOH/CH3COOH
50% CF3COOH/CH3COOH
50% CF3COOH/CH3COOH
CH3COOHi
50% CF3COOH/CH3COOH
80s CF3COOH/CH3COOH
CF3COOH
CF3COOHi
Yield,@2
C6H5OCOCH3
C6H5CH20COCH3
4-CH3C6H40COCH3
4-CH30C6H4OCOCH3
4-C6H5C6H4OCOCH3
4-SrC6H4OCOCH3
C6H5OCOC6H5
Caprolactone
00
88
79
81
a4
78
81
79
a Reactions at room temperature unless indicated otherwise.
!? No attempt was made to optimise yields.
C Refers to pure, recrystallised or redistilled material.
2 Reaction carried out at 50-60°C.
Oxidat&ve Cleavage o? N,N-Dimethylhydrazonesto Ketones
There are few convenient methods for the oxidative regeneration of ketones
from N,N-dimethylhydrazones, and the most commonly used reagent appears to be
reactions
observed
with
sodium periodate.0 In view of the slow Baeyer-Villiger
ketones
and sodium
reactivity
Smooth
of
oxidative
perborate
a variety
acetic
ketone
deprotection
were no complications
of
in
of
was
acid,
observed
Data for
Cleavage
of
was of
to
the
reagent
and,
as
expected,
are
- 3-cn30
=
4-CH30
4-Br
3-NO2
4-NO2
a
No attempt
1
Refers
derivative
in Table
Ketone
Hydrazone
Yield,
94
0
59
jN(CH3J2
z-C3H7CC3H7-"
was made to optlmise
to pure,
recryatallised
IV.
to Ketones with
NN(CH3)2
83
83
86
89
a4
97
92
91
- 2-CH30
there
Acid
fllN(CH3)2
C6H5CCH2CH3
R
R-H
- 4-CH3
the
given
the
system.
IV
N,N-Dimethylhydrazones
Ketone
Yield, $a*b
examine
to
even with
examples
Sodium Psrborate/Acetic
Hydrazone
interest
SO-60°C
oxidation,
representative
Table
Oxidative
at
due to Baeyer-Villiger
4-methoxyacetophenone.
it
N,N-dimethylhydrazones
53
yields.
or redistilled
material.
e@b
Functional group oxidation
Oxidation
of Hydroquinonea
Only
for
a very
phenol
study
as
oxidation,
quinones.
A number
excellent
yields
but the
o%idations
and Phenols
limited
of
of
of
to Pufnones
of the utility
was undertaken
many
reagents
are
available
results
are
summarised
typical
qulnones
were obtained
phenols
uere
mixtures
of products
were obtained
obtained
from highly
substituted
less
from
of
the
yields
or sterically
Hydroquinones
of
for
sodium
the
in
of
Table
pure
encumbered
perborate
preparation
corresponding
In most cases
suocessful.
and moderate
Table
Oxidation
1757
of
Good
V.
to
hydroquinones,
rather complex
quinones
were only
phenols.
V
and Phenols
Sodium Perborate/Acetic
to Quinones
with
Acid
0
R2
H
H
OH
H
H
64
H
OH
H
H
85
95
H
85
OH
H
96
H
OH
H
H
86
CH-CH-CH-CH
OH
H
H
79
The
No attempt
!?
Refers
safety
discharged
the
it,
at
reagent
are
completely
least
used,
clearly
the
of
public
is
drainage
certain
important
conditions
and
olefins
contrast
oxidations
of other
of
sodium
used
these
types
day.
and,
in
-
oxidant
thousands
groups
the
acetylenes
situation
functtonal
of
is
groups,
A further
functional
the
perborate
useful
innocuous
and
to
material.
functional
an especially
every
standard
in
that
completely
systems
protection/deprotection
perborate
is
the
Hence)
yields.
certain
that
unaffected,
all.
of
handling,
are
47
or redistilled
demonstrate
oxidation
by-products
under
at
recrystallised
$asP
53
42
c*3
(CH313C
was made to optimise
and ease
Into
of
if
for
The
CH3
H
to pure,
results
H
CR3
H
2
reagent
(CR3)3C
H
CH3
H
above
CH3
H
H
CH3
work.
during
Ii
H
effective
Of cost,
are
OH
OH
CH3
(CH313C
slowly
R3
CH3
H
CH3
scale
Yield,
R’
are
of
are
not
oxidised
is
not
terms
large
tons
are
feature
affected
study.
when many other
groups
highly
in
for
attractive
present
a
by
Alcohols
only
very
oxidants
necessary
functionality.
EXPERIMENTAL
General
Procedure for Oxidation
of Aniltnes.
A solution
of the aniline
(0.01
mol) in glacial
acetic
acid
(20 ml) uas added slowly
(ca.
1 h) to a stirred
suspensfon
of sodium perborate
tetrahydrate
(8.3 g, 5 eq) in glacial
acetic
acid
maintained
at 50-60°C.
The reaction
mixture
uas stirred
at 50-60°C
for a total
A. MCKILLOP and J. A. TARBIN
1758
of 1 .5-2
h. after
which separation
of sodium borate
uas comolete.
The mixture
was cooled;
the inorganic
salts
removed by filtration,
and iced water (ca.
250
ml) added.
The crude
nitro
COmpOUnd was obtained
by filtration
or olvent
extraction
and purified
by short
column chromatography
-followed
by distillation
or crystallisation.
General Procedure
Por
in
one
portion
to
(1.66-l
.83 g,
l-l.2
formation)
in glacial
continued
at 50-60°C
and the crude product
Oxidation
oP Sulphldes.
The sulphide
(0.01 mol) was added
a stirred
sodium
perborate
tetrahydrate
suspension
of
eq for
sulphoxlde
formation;
8.3 g, 5 eq Por sulphone
acetic
acid
(70 ml) maintained
at 50-6OOC.
Stirring
was
for 1 .5-3 h, until
separation
of sodium borate was complete
then isolated
and purified
as described
above.
General Procedure
Por Ketone Oxidation
(see
DerbOrate
tetrahydrate
in 30 ml of solvent
the mixture
stirred
for 4-8 h.
The crude
described
above,
Table III).
3 Eq (4.98 g) of sodium
was used per 0.01 mol of ketone and
product
was isolated
and purified
as
4 Eq (6.65
g) of
General
Procedure
Por Oxidation
OP N,N-Dlmethylhydrazones.
sodium perborate
tetrahydrate
in 30 ml of glacial
acetic
acid was used per 0.01
The
mol of -dimethylhydrazone,
and the mixture- stirred
at 50-60°C
for 3-5 -h.
crude product
was isolated
and purified
as described
above.
For hydroquinones,
General Procedure
Por Oxidation
oP Hydroquinones
and Phenols.
mol of
3 eq (4.98
g) of sodium
perborate
tetrahydrate
were used
per 0.01
substrate,
for
phenols,
5 ~eq of oxidant
(8.3
g) were used -per 0.01
mol of
substrate.
Glacial
acetic
acid
(20 ml) was used as solvent
for all
the examples
for which trifluoroacetic
acid was
glven in Table V except
2,6-di-t-butylphenol,
All reactions
were carriFd
out at 50-60°C
for 2-4 h, and crude products
used.
were isolated
and purified
as described
above.
Acknowledgement.
We gratefully
work by the Ministry
of Defence.
acknowledge
generous
financial
support
of
this
REFERENCES
1.
Preliminary
communication:
21(, 1505 (1983).
2.
C.F.H.
3.
A. Rashld
4.
S.M.
5.
L. Huestls,
6.
D.S.
7.
A. Hansson,
8.
T.W.
Inc.,
Allen
and J.H.
and G. Read,
A.
Clark,
J.
Matteson
Chem. Ed., s,
and R.J.
Acta
J.
Moody,
Chem. Stand.,
and J.A.
Chem. Ed.,
Chem. Sot.,
Mehta and M.V. Vakilwala,
J.
McKillop
J.
327
J.
1323
Tetrahedron
Lett.,
72 (1942).
(1967).
Am. Chem. Sot.,
2,
563
(1952).
(1977).
Org.
Is,
“Protective
Groups
Greene,
New York, 1981, pp 142-143.
2,
19,
Tarbin,
Chem.,
45,
1091
(1980).
934 (1961).
in
Organic
Synthesis”,
John
Wiley
h Sons,

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