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Iodide ion promotion of benzyl chloride-borate ester carbonylation reactions
Tetrahedron Letters,Vol.26,No.l9,rm Printed in Great Britain
IODIDE ION PROMOTION Howard
Alpera,
aDepartynt
Nathalie
B.P. Research Summary:
Esters
chlorides
with borate
Recently, types
are isolated esters
esters
done in several
promoter,* esters,
examples
benzyl chlorides benzyl
chlorides
Treatment
the Monsanto
conditions
benzylic
cata1yst.l
acetic
acid process,3
of bentyl
iodide. bromides
It is known
from
as an effective
and the homologation
that the rhodium
to all
It was disappointing
that iodide ion can function
chlorides
catalyzed
esters and potassium
the promotional
with a borate ester,
potassium
[1,5-HDRhCl],
of acids,4
carbonylation
iodide.
of
We now wish to of
[R'=C,H,,
the corresponding
described
of small amounts
The product yields,
effect
B(OR'13,
iodide, and a catalytic
afforded
to those previously
and the addition
was 2-3/0.2/0.1).
demonstrate
reaction
of potassium
to convert
and a rhodium(I)
carbon monoxide,
are identical
in substrate
halide:Rh:KI
catalyzed
to esters.
dimer of chloro(l,5-hexadiene)rhodium the change
U.K., TW16 7LN
ion does indeed result in a simple and clean conversion
of a series of benzylic
i-C,H7,n-C,Hs,i-C,Hs,t-C,+Hs], reaction
Middlesex,
in the presence
by use of borate
of iodide
Ontario,
from the rhodium(I)
it was anticipated
could be achieved
that the presence
Canada KIN 984
Ottawa,
failed to react in the same manner.
areas of catalysis
Therefore,
report
B. Woella
of Ottawa,
the use of borate esters chlorides
REACTIONS
David J.H. Smithb and James
by carbon monoxide
including
and ethers5.
ESTER CARBONYLATION
Sunbury-on-Thames,
in fine yields
to learn that the corresponding research
Hamela,
and carbon monoxide,
we have described
of carboxylic
CHLORIDE-BORATE
University
Centre,
$3.00 + .oo Pergamon Press Ltd.
01985
OF BENZYL
of Chemistry,
0040-4039185
2273-2274,1985
amount of the
esters.
for the bromides',
of potassium
which are listed
of iodide ion since no reaction
iodide
for
(mm01 ratio of
in Table
occurs
These
except
1, clearly
in the absence
of the
latter. What benzylic readily
role does iodide chloride
ion play in these reactions ?
to the more reactive
occur in polar solvents
treatment without
of l-chloromethylnaphthalene
borate ester
alternative rhodium
[heptane
explanation
intermediate',
carbonyl
benzyl
chloride
dimer
iodide.
such as acetone6,
Although
with an equivalent
catalyst
such a process
would
amount
is known
Prior to the formation
be converted
to
iodide with or
of B(OC,H,),].
An
of any boron-
by carbon monoxide
(one can, in fact, use the latter as the catalyst
the
takes place on
of potassium
in the absence
the rhodium catalyst.
the rhodium(I)
is that it converts
we found that no reaction
was used as the solvent
involves
One possiblity
to rhodium-
for the reaction
of
KI [1,5-HDRhCl], + benzyl
bromides).
active
catalyst.
methylnapthalene in 98% yield, suggest
Iodide
+
[Rh(C012Cl],
ion can then displace
This hypothesis
was confirmed
with B(OCH(CH,)z),
compared
CO
to 68% yield
that the key catalytic
chloride
species
[Rh(CO)21]z
to give [Rh(CO)21]2
by [Rh(CO)21],7
and carbon monoxide resulting
-
catalyzed
which may be a more
reaction
from the use of [I,5 HDRhCl ]JKI.
in the benzyl chloride
iodide complex.
2273
of l-chloro-
(no KI) to form the anticipated reactions
These
is a rhodium
ester results
carbonyl
2214
Table
1
Iodide
Ion Promotion
of the Reaction
of Benzylic
Chlorides
with CO and B(OR),
a ArCH,Cl Ar= Ph
Yield,%
PhCH,COOC,H,
C2%
71
n-C,Hs
PhCH2COOC,H9-n
i-C,H,
PhCH,COOC,H,-i
44
PhCH,COOC(CH,),
56
C2%
p-CH&H,CH2COOC2Hs
56
CH(CH,),
p-CH,C,H,CH2COOCH(CH,),
70
p-CH,C,H,CH2COOC,H,
72
C2”s
o-CH,OC,H,CH,COOC,H,
100
C(CH,),
o-CH,OC,H,CH,COOC(CH,),
55
C2H5
1-C1,H7CH2COOC2H,
54
CH(CH,),
1-C,,H,CH,COOCH(CH,),
68
C2H5
m-CH,C,H,CH,COOC,H,
87
CH(CH,),
m-CH,C,H,CH,COOCH(CH,),
82
CzH5
p-FC,H,CH2COOC2H,
93
C(CH,), P-CH,C,H,
n-C,Hs o-CH,OC,H,
‘-ClOH7
m-CHsC,H,
P-F&H, iProducts
b
Product
B(OR'I, R'=
were fully characterized
by comparison
100
with authentic
materials.
Isolated yields. In conclusion, with
borate esters
process
potassium
iodide is a valuable
and carbon monoxide.
than that involving
promoter
From a commercial
benzyl bromides
of the reaction viewpoint,
of benzyl chlorides
this is a more economical
as substrates.
Acknowledgements We are indebted Council,
for support
to British
Petroleum,
and to the Natural
Sciences
and Engineering
Resaerch
of this work. References
Woell, J.B.; Alper, H. Tetrahedron Lett. 1984, 25, 3791. Sheldon, R.A. "Chemicals from Synthesis Gas", DTReidel Publ. Co., Dordrecht, Holland, 1983, pp. 140-166. 3. Forster, D. Adv. Organometal. Chem. 1979, 17, 255. Knifton, J.F. J. Chem. Sot., Chem. Commun. l-981, 41. 54: Graca, G.; Sbrana, G.; Valentini, G.; Andrich, G.; Gregorio, G.; J. Am. Chem. Sot. 1978, 100, 6238. 6. Ingold, C.K. "Structure and Mechanism in Organic Chemistry", Cornell University Press, Ithaca, New York, 1953, pp. 322-323. 7. Palyi, G.; Vizi-Orosz, A.; Marko, L.; Marcati, F.; Bor, G. 3. Organometal. Chim. 1974, 66_, 295. 1. 2.
(Received
in USA 19 November
1984)
IODIDE ION PROMOTION Howard
Alpera,
aDepartynt
Nathalie
B.P. Research Summary:
Esters
chlorides
with borate
Recently, types
are isolated esters
esters
done in several
promoter,* esters,
examples
benzyl chlorides benzyl
chlorides
Treatment
the Monsanto
conditions
benzylic
cata1yst.l
acetic
acid process,3
of bentyl
iodide. bromides
It is known
from
as an effective
and the homologation
that the rhodium
to all
It was disappointing
that iodide ion can function
chlorides
catalyzed
esters and potassium
the promotional
with a borate ester,
potassium
[1,5-HDRhCl],
of acids,4
carbonylation
iodide.
of
We now wish to of
[R'=C,H,,
the corresponding
described
of small amounts
The product yields,
effect
B(OR'13,
iodide, and a catalytic
afforded
to those previously
and the addition
was 2-3/0.2/0.1).
demonstrate
reaction
of potassium
to convert
and a rhodium(I)
carbon monoxide,
are identical
in substrate
halide:Rh:KI
catalyzed
to esters.
dimer of chloro(l,5-hexadiene)rhodium the change
U.K., TW16 7LN
ion does indeed result in a simple and clean conversion
of a series of benzylic
i-C,H7,n-C,Hs,i-C,Hs,t-C,+Hs], reaction
Middlesex,
in the presence
by use of borate
of iodide
Ontario,
from the rhodium(I)
it was anticipated
could be achieved
that the presence
Canada KIN 984
Ottawa,
failed to react in the same manner.
areas of catalysis
Therefore,
report
B. Woella
of Ottawa,
the use of borate esters chlorides
REACTIONS
David J.H. Smithb and James
by carbon monoxide
including
and ethers5.
ESTER CARBONYLATION
Sunbury-on-Thames,
in fine yields
to learn that the corresponding research
Hamela,
and carbon monoxide,
we have described
of carboxylic
CHLORIDE-BORATE
University
Centre,
$3.00 + .oo Pergamon Press Ltd.
01985
OF BENZYL
of Chemistry,
0040-4039185
2273-2274,1985
amount of the
esters.
for the bromides',
of potassium
which are listed
of iodide ion since no reaction
iodide
for
(mm01 ratio of
in Table
occurs
These
except
1, clearly
in the absence
of the
latter. What benzylic readily
role does iodide chloride
ion play in these reactions ?
to the more reactive
occur in polar solvents
treatment without
of l-chloromethylnaphthalene
borate ester
alternative rhodium
[heptane
explanation
intermediate',
carbonyl
benzyl
chloride
dimer
iodide.
such as acetone6,
Although
with an equivalent
catalyst
such a process
would
amount
is known
Prior to the formation
be converted
to
iodide with or
of B(OC,H,),].
An
of any boron-
by carbon monoxide
(one can, in fact, use the latter as the catalyst
the
takes place on
of potassium
in the absence
the rhodium catalyst.
the rhodium(I)
is that it converts
we found that no reaction
was used as the solvent
involves
One possiblity
to rhodium-
for the reaction
of
KI [1,5-HDRhCl], + benzyl
bromides).
active
catalyst.
methylnapthalene in 98% yield, suggest
Iodide
+
[Rh(C012Cl],
ion can then displace
This hypothesis
was confirmed
with B(OCH(CH,)z),
compared
CO
to 68% yield
that the key catalytic
chloride
species
[Rh(CO)21]z
to give [Rh(CO)21]2
by [Rh(CO)21],7
and carbon monoxide resulting
-
catalyzed
which may be a more
reaction
from the use of [I,5 HDRhCl ]JKI.
in the benzyl chloride
iodide complex.
2273
of l-chloro-
(no KI) to form the anticipated reactions
These
is a rhodium
ester results
carbonyl
2214
Table
1
Iodide
Ion Promotion
of the Reaction
of Benzylic
Chlorides
with CO and B(OR),
a ArCH,Cl Ar= Ph
Yield,%
PhCH,COOC,H,
C2%
71
n-C,Hs
PhCH2COOC,H9-n
i-C,H,
PhCH,COOC,H,-i
44
PhCH,COOC(CH,),
56
C2%
p-CH&H,CH2COOC2Hs
56
CH(CH,),
p-CH,C,H,CH2COOCH(CH,),
70
p-CH,C,H,CH2COOC,H,
72
C2”s
o-CH,OC,H,CH,COOC,H,
100
C(CH,),
o-CH,OC,H,CH,COOC(CH,),
55
C2H5
1-C1,H7CH2COOC2H,
54
CH(CH,),
1-C,,H,CH,COOCH(CH,),
68
C2H5
m-CH,C,H,CH,COOC,H,
87
CH(CH,),
m-CH,C,H,CH,COOCH(CH,),
82
CzH5
p-FC,H,CH2COOC2H,
93
C(CH,), P-CH,C,H,
n-C,Hs o-CH,OC,H,
‘-ClOH7
m-CHsC,H,
P-F&H, iProducts
b
Product
B(OR'I, R'=
were fully characterized
by comparison
100
with authentic
materials.
Isolated yields. In conclusion, with
borate esters
process
potassium
iodide is a valuable
and carbon monoxide.
than that involving
promoter
From a commercial
benzyl bromides
of the reaction viewpoint,
of benzyl chlorides
this is a more economical
as substrates.
Acknowledgements We are indebted Council,
for support
to British
Petroleum,
and to the Natural
Sciences
and Engineering
Resaerch
of this work. References
Woell, J.B.; Alper, H. Tetrahedron Lett. 1984, 25, 3791. Sheldon, R.A. "Chemicals from Synthesis Gas", DTReidel Publ. Co., Dordrecht, Holland, 1983, pp. 140-166. 3. Forster, D. Adv. Organometal. Chem. 1979, 17, 255. Knifton, J.F. J. Chem. Sot., Chem. Commun. l-981, 41. 54: Graca, G.; Sbrana, G.; Valentini, G.; Andrich, G.; Gregorio, G.; J. Am. Chem. Sot. 1978, 100, 6238. 6. Ingold, C.K. "Structure and Mechanism in Organic Chemistry", Cornell University Press, Ithaca, New York, 1953, pp. 322-323. 7. Palyi, G.; Vizi-Orosz, A.; Marko, L.; Marcati, F.; Bor, G. 3. Organometal. Chim. 1974, 66_, 295. 1. 2.
(Received
in USA 19 November
1984)