Mild and efficient method for decarboxylative bromination of α,β-unsaturated carboxylic acids with Dess-Martin periodinane

Article abstract of DOI:10.1055/s-2005-917077

A simple and mild method for decarboxylative bromination of α,β-unsaturated carboxylic acids has been developed using Dess-Martin Periodinane (DMP) in combination with tetraethylammonium bromide (TEAB) at room temperature. High yields of the corresponding bromoalkenes were obtained. Georg Thieme Verlag Stuttgart.

Full text of DOI:10.1055/s-2005-917077

LETTER
2495
Mild and Efficient Method for Decarboxylative Bromination of
a,b-Unsaturated Carboxylic Acids with Dess–Martin Periodinane
M
ildand Efficient
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omination of
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elvekar,* Nitin D. Arote, Omkar P. Herlekar
Department of Pharmaceutical Sciences and Technology, University Institute of Chemical Technology, Matunga, Mumbai 400019, India
Fax +91(22)24145614; E-mail: vikastelvekar@rediffmail.com
Received 14 March 2005
For our initial studies, cinnamic acid was chosen as sub-
Abstract: A simple and mild method for decarboxylative bromina-
strate and the reaction with DMP in combination with
TEAB was performed. A mixture of cinnamic acid (1.0
tion of a,b-unsaturated carboxylic acids has been developed using
Dess–Martin Periodinane (DMP) in combination with tetraethylam-
mmol), DMP and TEAB (1.1 mmol) in anhydrous dichlo-
romethane was stirred at room temperature. It was
observed that the starting material was consumed within
15 minutes as indicated by TLC analysis. After work-up
and purification by silica gel column chromatography
(hexane–EtOAc, 9:1), bromostyrene was isolated in 94%
yield (Scheme 1).
monium bromide (TEAB) at room temperature. High yields of the
corresponding bromoalkenes were obtained.
Key words: Dess–Martin periodinane, tetraethylammonium bro-
mide , decaboxylation, bromoalkenes
Decarboxylation of a,b-unsaturated carboxylic acids
accompanied by simultaneous replacement with halogen
is a useful reaction in organic chemistry for the synthesis
of halogenated organic substances.1 The original method
of halodecarboxylation, known as the Hunsdiecker reac-
tion, involves the reaction of a silver salt of a carboxylic
acid with bromine as a halogen source. The classical
Hunsdiecker reaction has been modified and developed Scheme 1 Bromo-decarboxylation of cinnamic acid using DMP
and TEAB
with particular attention paid to green chemistry
aspects,2,3 operation under additive free conditions,4 as
well as catalysis using salts of mercury,5 lithium,6 lead,7
Encouraged by these results further development work
manganase,8 or tetraalkylammonium salts.9 Tokuda and
was undertaken. A variety of a,b-unsaturated aromatic
co-workers have reported a microwave-assisted reaction
in the presence of metal salts.10 Halodecarboxylation has
also been reported with trivalent iodine species in combi-
nation with N-halosuccinimide as a halogen source.11,12
Although, most of these methods are satisfactory, the use
of more complex reagents and sometimes tedious work-
up means that there is still scope for alternative reagent
systems for decarboxylative bromination.
carboxylic acids were subjected to the reaction condi-
tions,14 and the results are presented in the Table 1.
The results presented in Table 1 clearly indicate that a,b-
unsaturated carboxylic acids substituted with electron do-
nating groups like methyl or methoxy undergo very fast
oxidative bromo-decarboxylation (Table 1, entries 2, 3) in
a short reaction time and good yields. On the other hand,
if the aromatic ring is substituted with an electron with-
drawing group such as nitro, or chloro, comparatively
lower yields and slower reaction rates are observed
(Table 1, entries 4–8).
Hypervalent iodine reagents and reagent systems have
found widespread application in organic synthesis be-
cause of their selectivity and simplicity of use. Ever since
the innovative work by Dess and Martin, explorations into
the chemistry of hypervalent iodine compounds have be-
come the subject of growing interest due to their mild na-
ture. Our group has been working extensively on the
development of novel methodologies under mild reaction
conditions using the petavalent iodine reagent o-iodoxy
benzoic acid (IBX).13 Herein, we report our results on
decarboxylative brominatiom of a,b-unsaturated carboxy-
lic acids using DMP in combination with TEAB at room
temperature.
With the same reagent system heterocyclic a,b-unsaturat-
ed carboxylic acids such as 3-(2-furyl)acrylic acid also
gave good yields of the corresponding brominated prod-
uct (Table 1, entry 10). Some aliphatic a,b-unsaturated
acids were also subjected to these conditions; crotonic
acid (Table 1, entry 11) and 3,3-dimethylacrylic acid
(Table 1, entry 12) were converted to the corresponding
bromo compounds in 30 minutes.
In summary a novel method has been developed for decar-
boxylative bromination with DMP in combination with
TEAB in anhydrous dichloromethane at room tempera-
ture. The method developed is mild and gave good to
excellent yields of bromoalkenes for both aliphatic as well
as aromatic substrates.
SYNLETT 2005, No. 16, pp 2495–2497
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Advanced online publication: 21.09.2005
DOI: 10.1055/s-2005-917077; Art ID: D06805ST
© Georg Thieme Verlag Stuttgart · New York

2496
V. N. Telvekar et al.
LETTER
Table 1 Bromo-decarboxylation Using DMP and TEABa
Entry
1
Substrateb
Product
Time (h)
0.25
Yield (%)c
94
2
3
0.25
0.25
90
92
4
5
6
12
12
14
68
72
65
7
8
16
15
65
70
9
12
72
92
10
0.25
11
12
0.50
0.50
78
82
a Reaction conditions: substrate (1.0 equiv), DMP (1.1 equiv), TEAB (1.1 equiv), anhyd CH2Cl2, r.t.
b Starting compounds were prepared by standard literature procedures.
c Isolated yields after column chromatography. Structures confirmed by comparison of the IR and 1H NMR spectra with those of authentic ma-
terials.
(4) (a) Homsi, F.; Rousseau, G. Tetrahedron Lett. 1999, 40,
Acknowledgment
1495. (b) Homsi, F.; Rousseau, G. J. Org. Chem. 1999, 64,
NA thanks CSIR, New Delhi, for the award of a Senior Research
81.
Fellowship.
(5) Cristol, S. J.; Firth, W. C. Jr. J. Org. Chem. 1961, 26, 280.
(6) (a) McKillop, A.; Bromely, D.; Taylor, E. C. J. Org. Chem.
1969, 34, 1172. (b) Naskar, D.; Roy, S. J. Chem. Soc.,
Perkin Trans. 1 1999, 2435.
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Synlett 2005, No. 16, 2495–2497 © Thieme Stuttgart · New York

LETTER
Mild and Efficient Method for Decarboxylative Bromination of a,b-Unsaturated Carboxylic Acids
2497
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(14) General experimental procedure: To a stirred suspension
of DMP (1.1 equiv) in anhyd CH2Cl2 (15 mL) was added
TEAB (1.1 equiv) in one portion. The resultant mixture was
stirred r.t. for 5 min followed by addition of a,b-unsaturated
carboxylic acid (1.0 equiv) and stirring was continued at r.t.
until the starting material had been completely consumed
(TLC). The reaction mixture was diluted with CH2Cl2 and
washed successively with 10% aq sodium bisulfite solution
(2 × 15 mL), 10% NaHCO3 (2 × 15 mL), H2O (1 × 10 mL),
and brine (1 × 10 mL). The organic layer was dried over
Na2SO4 and concentrated in vacuo. The residue obtained
was purified by silica gel column chromatography (10%
EtOAc–hexane) to afford pure bromoalkenes.
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Synlett 2005, No. 16, 2495–2497 © Thieme Stuttgart · New York