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Preparation of aldehydes and ketones by oxidation of benzylic hydrocarbons with benzeneseleninic anhydride
Tetrahedron Letters No. 35, pp 3331 - 3334. @Pergamon Press Ltd. 1979.Printed in Great Britain.
PREPARATION OFALDEHYDESAND
KETONES BY OXIDATION OF BENZYLIC HYDROCARBONS WITH
BENZENESELENINIC ANHYDRIDE Derek H.R. Barton, Department
Raymond
A.H.F.
of Chemistry,
Hui, David J. Lester and Steven V. Leygc Imperial
College,
London SW7 2AY
Summary: Benzeneseleninic anhydride is a mild oxidant for the conversion of benzylic hydrocarbons into aldehydes or ketones.
Although
oxidation
of aromatic
still a need for new reagents
side chains can be achieved
by a variety
which will effect this transformation.
of methods,
Recently
there is
benzenesele-
ninic anhydride has been used as a mild and versatile oxidant for a number of different 1 nit substrates and appeared to be suitable for benzylic oxidation also. Ph!eOlePh
Ar-CH2-R.
Thus we find that xylenes
can be treated
to give the corresponding
monoaldehydes
the aldehydes
were isolated
able to isolate substantially
A number rate studies reacted
with substantial
for by the formation
amounts
Other compounds
of phenylglyoxal
Finally,
Ethyl benzene
sion to the aldehyde added
camphor
further
(2 eq.) further
at 132O
we were also
of the acid could be
were used.
The low yield
with the anhydride
investigated
(Table).
Crude
while -p-methoxytoluene in the E-methoxytoluene anisole
afforded
reac-
as a major product the aldehyde
together
products.
include
diphenylmethane
gave acetophenone
gave camphorquinone to investigate
However,
oxidation
The yields
of 2-phenylseleno-4-methyl
mechanistic
was obtained.
Aryl
In other experiments
were similarly
(10%) was also formed,presumably
it was of interest
in the hope of obtaining
hydride
aromatics
of phenylselenated
In accord with this result, dride.
acid.
of the anhydride
also on oxidation
Alkyl
q
(0.33 mol equivalents)
was inert to the anhydride
which were oxidised
90% yield after 4 days. amount
substituted
q
Owing to the small scale of these reactions,
about three times faster than the xylenes.
1-Methylnaphthalene
R=H
derivatives.
of the corresponding
showed that p-nitrotoluene
tion was accounted (40%).
(Table).
when large excesses
of other methyl
R ArCR
neat with the anhydride
as their 2,4-DNP
small amounts
increased
*
orga-
on extended
produced
in 60% yield although by further
oxidation
in 74 % after oxidation
the oxidation
information.
which gave benzophenone
a significant of acetophenone. with the anhy-
of 9,10-dimethylanthracene
Under mild conditions, reaction
anthraquinone
in
times
good conver-
(20 h) with more an-
in 64% yield.
3332
No. 35
In the above reactions,at elevated temperatures, it is possible to use benzeneseleninic acid as an alternative oxidant.
TABLE
STARTING MATERIAL
PRODUCT(S)
a \ I/
CHO
CHO
Q
/05 \ \ / I
\ I/
J3
Me0
42f
(b)
0.33 equiv. BSA 10 h
/co \ \/
(b)
0.33 equiv. BSA 10 h
CHO
% YIELD
0.33 equiv. BSA 10 h
\ I/
/\ I 0
REACTION CONDITIONS (d)
(b)
CHO
I
0.25 equiv. BSA 14 h
37na
(c,
CHO 0.33 equiv. BSA 4 h
(c)
15
Me0
CHO 2 equiv. BSA 2.5 h
cc)
9
Me0 40
/continued
No. 35
3333
Table/continued
STARTING MATERIAL
PRODUCT(S)
REACTION CONDITIONS (d)
% YIELD
CHO 0.33 equiv. BSA 1 week
38*
(b)
0.33 equiv. BSA 2h
(a)
(b)
1 equiv. BSA 15 min
PhCH2Ph
PhCOPh
(a)
(b)
0.5 equiv. BSA 4 days
59
90
(a) (c)
CHO 1 equiv. BSA 2.5 h
(a)
51
(c)
CHO 14
CHO
*
As 2,4-DNP derivative
(b) At refhz
14f Based on starting material consumed
(c) At 120'
(a) In dry chLorobenzene
(d) AZ1 reactions done under nitrogen 021argon
Addendum: Recently T.G. Backlg showed that benzeneseleninic anhydride is an excellent reagent for the dehydrogenationof cyclic lactams. We can add that it is also an excellent reagent for the dehydrogenationof cyclic lactones [(l) + (2)]. However, it is not efficient for the dehydrogenationof acyclic esters.
No. 35
1 equiv. BSA PhCl/120°
90%
42 h
0 H (1)
(2)
We thank the Beit Trust for a Fellowship (to D.J.L.).
REFERENCES
1.
(a) D.H.R. Barton, 985 (1976);
A.G. Brewster,
(b) M.R. Czamy,
S.V. Ley, and M.N. Rosenfeld,
ibid.,
81 (1976);
and M.N. Rosenfeld,
ibid.,
ibid.,
445 (1977);
(d) D.H.R. Barton,
Perkin
I, 567 (1977);
751 (1977);
T.G. Back, ibid.,
(Received
952 (1978).
in UK 18 June 1979)
N.J. Cussans,
(h) D.H.R.
S.V. Ley,
and S.V. Ley,
and M.N. Rosenfeld,
J.C.S.
Chem. Comm.,
131 and 276 (1978);
Barton, N.J. Cussans, R.A.H.F.
Chem. Conun.,
A.G. Brewster,
and S.V. Ley, J.C.S.
S.V. Ley, ibid.,
A.G. Brewster,
J.C.S.
D.J. Lester,
S.V. Ley, P.D. Magnus,
D.J. Lester,
278 (1978);
(i) D.H.R. Barton,
Barton,
(c) D.H.R. Barton,
(e) D.H.R. Barton,
(f) D.H.R. Barton,
(g) T.G. Back, ibid., 393 (1978);
147 (1977);
D.H.R.
S.V. Ley, ibid.,
Hui, D.J. Lester,
S.V. Ley, and
PREPARATION OFALDEHYDESAND
KETONES BY OXIDATION OF BENZYLIC HYDROCARBONS WITH
BENZENESELENINIC ANHYDRIDE Derek H.R. Barton, Department
Raymond
A.H.F.
of Chemistry,
Hui, David J. Lester and Steven V. Leygc Imperial
College,
London SW7 2AY
Summary: Benzeneseleninic anhydride is a mild oxidant for the conversion of benzylic hydrocarbons into aldehydes or ketones.
Although
oxidation
of aromatic
still a need for new reagents
side chains can be achieved
by a variety
which will effect this transformation.
of methods,
Recently
there is
benzenesele-
ninic anhydride has been used as a mild and versatile oxidant for a number of different 1 nit substrates and appeared to be suitable for benzylic oxidation also. Ph!eOlePh
Ar-CH2-R.
Thus we find that xylenes
can be treated
to give the corresponding
monoaldehydes
the aldehydes
were isolated
able to isolate substantially
A number rate studies reacted
with substantial
for by the formation
amounts
Other compounds
of phenylglyoxal
Finally,
Ethyl benzene
sion to the aldehyde added
camphor
further
(2 eq.) further
at 132O
we were also
of the acid could be
were used.
The low yield
with the anhydride
investigated
(Table).
Crude
while -p-methoxytoluene in the E-methoxytoluene anisole
afforded
reac-
as a major product the aldehyde
together
products.
include
diphenylmethane
gave acetophenone
gave camphorquinone to investigate
However,
oxidation
The yields
of 2-phenylseleno-4-methyl
mechanistic
was obtained.
Aryl
In other experiments
were similarly
(10%) was also formed,presumably
it was of interest
in the hope of obtaining
hydride
aromatics
of phenylselenated
In accord with this result, dride.
acid.
of the anhydride
also on oxidation
Alkyl
q
(0.33 mol equivalents)
was inert to the anhydride
which were oxidised
90% yield after 4 days. amount
substituted
q
Owing to the small scale of these reactions,
about three times faster than the xylenes.
1-Methylnaphthalene
R=H
derivatives.
of the corresponding
showed that p-nitrotoluene
tion was accounted (40%).
(Table).
when large excesses
of other methyl
R ArCR
neat with the anhydride
as their 2,4-DNP
small amounts
increased
*
orga-
on extended
produced
in 60% yield although by further
oxidation
in 74 % after oxidation
the oxidation
information.
which gave benzophenone
a significant of acetophenone. with the anhy-
of 9,10-dimethylanthracene
Under mild conditions, reaction
anthraquinone
in
times
good conver-
(20 h) with more an-
in 64% yield.
3332
No. 35
In the above reactions,at elevated temperatures, it is possible to use benzeneseleninic acid as an alternative oxidant.
TABLE
STARTING MATERIAL
PRODUCT(S)
a \ I/
CHO
CHO
Q
/05 \ \ / I
\ I/
J3
Me0
42f
(b)
0.33 equiv. BSA 10 h
/co \ \/
(b)
0.33 equiv. BSA 10 h
CHO
% YIELD
0.33 equiv. BSA 10 h
\ I/
/\ I 0
REACTION CONDITIONS (d)
(b)
CHO
I
0.25 equiv. BSA 14 h
37na
(c,
CHO 0.33 equiv. BSA 4 h
(c)
15
Me0
CHO 2 equiv. BSA 2.5 h
cc)
9
Me0 40
/continued
No. 35
3333
Table/continued
STARTING MATERIAL
PRODUCT(S)
REACTION CONDITIONS (d)
% YIELD
CHO 0.33 equiv. BSA 1 week
38*
(b)
0.33 equiv. BSA 2h
(a)
(b)
1 equiv. BSA 15 min
PhCH2Ph
PhCOPh
(a)
(b)
0.5 equiv. BSA 4 days
59
90
(a) (c)
CHO 1 equiv. BSA 2.5 h
(a)
51
(c)
CHO 14
CHO
*
As 2,4-DNP derivative
(b) At refhz
14f Based on starting material consumed
(c) At 120'
(a) In dry chLorobenzene
(d) AZ1 reactions done under nitrogen 021argon
Addendum: Recently T.G. Backlg showed that benzeneseleninic anhydride is an excellent reagent for the dehydrogenationof cyclic lactams. We can add that it is also an excellent reagent for the dehydrogenationof cyclic lactones [(l) + (2)]. However, it is not efficient for the dehydrogenationof acyclic esters.
No. 35
1 equiv. BSA PhCl/120°
90%
42 h
0 H (1)
(2)
We thank the Beit Trust for a Fellowship (to D.J.L.).
REFERENCES
1.
(a) D.H.R. Barton, 985 (1976);
A.G. Brewster,
(b) M.R. Czamy,
S.V. Ley, and M.N. Rosenfeld,
ibid.,
81 (1976);
and M.N. Rosenfeld,
ibid.,
ibid.,
445 (1977);
(d) D.H.R. Barton,
Perkin
I, 567 (1977);
751 (1977);
T.G. Back, ibid.,
(Received
952 (1978).
in UK 18 June 1979)
N.J. Cussans,
(h) D.H.R.
S.V. Ley,
and S.V. Ley,
and M.N. Rosenfeld,
J.C.S.
Chem. Comm.,
131 and 276 (1978);
Barton, N.J. Cussans, R.A.H.F.
Chem. Conun.,
A.G. Brewster,
and S.V. Ley, J.C.S.
S.V. Ley, ibid.,
A.G. Brewster,
J.C.S.
D.J. Lester,
S.V. Ley, P.D. Magnus,
D.J. Lester,
278 (1978);
(i) D.H.R. Barton,
Barton,
(c) D.H.R. Barton,
(e) D.H.R. Barton,
(f) D.H.R. Barton,
(g) T.G. Back, ibid., 393 (1978);
147 (1977);
D.H.R.
S.V. Ley, ibid.,
Hui, D.J. Lester,
S.V. Ley, and