LETTER
1563
Efficient Conversion of Alkyl Aryl Ketones to Aromatic Carboxylic Acids
Efficient
C
o
onversion
o
n
f
A
lkyl
A
ryl
g
K
etones to Aromat
C
ic Carboxylic
A
c
h
ids an Lee,* Ju-Hee Choi, Yong Chan Lee
Department of Chemistry, Chung-Ang University, Seoul 156-756, Korea
Fax +82(2)8254763; E-mail: jclee@cau.ac.kr
Received 27 July 2001
do]benzene (HTIB).9,10 Treatment of aromatic ketones
with HDNIB in CH3CN at reflux for 1–2 h produced the
-[(2,4-dinitrobenzene)sulfonyl]oxy ketone intermedi-
ates. Subsequent evaporation of solvent, the residue was
treated with Bu4NIO4 at reflux in 1,4-dioxane for addi-
tional 2 h to afford the carboxylic acids (Scheme). In the
present reaction conditions, both methyl aryl ketones and
-methylene aryl ketones reacted equally well to provide
the corresponding aryl carboxylic acids in high yields.
Abstract: An efficient method for the conversion of alkyl aryl ke-
tones to aromatic carboxylic acids has been developed based on ini-
tial formation of -organosulfonyloxy ketones and their subsequent
oxidation reactions by tetrabutylammonium periodate in one-pot
conditions.
Key words: carboxylic acids, cleavage, ketones, oxidations, perio-
date.
Conversion of alkyl aryl ketones to aryl carboxylic acids
received much attention due to the ready availability of
alkyl aryl ketones in industry.1 Many methods have been
O
O
O
Bu4NIO4
HDNIB
R
R
Ar
Ar
OH
Ar
reported for the oxidative degradation of alkyl aryl ke-
1,4-Dioxane
2 h
CH3CN
1 - 2 h
ODNs
tones to carboxylic acids. For example various methods
utilizing reagents such as sodium bromite,2 disodium ni-
trosylpentacyanoferrate(II),3 sodium nitrite/pyridinium
poly(hydrogen fluoride),4 tert-butyl hydroperoxide with
Re2O7,5 and KOH6 have been found effective for the oxi-
dative carbon-carbon cleavage reactions of alkyl aryl ke-
tones. However, all of these methods are suffered from the
need to use of either strong acidic or basic reaction condi-
tions. There has been only one literature method that con-
ducted under neutral reaction conditions, which utilized
C6F5I(OCOCF3)2 for the carbon-carbon bond cleavage re-
actions of methyl aryl ketones.7 However, the modest
yields obtained in such reaction conditions limits its prac-
tical applications for oxidative cleavage of aromatic ke-
tones. Furthermore, to our knowledge, no description has
been reported on the oxidative cleavage of carbon-carbon
bond of -methylene aryl ketones in satisfactory yields
under neutral reaction conditions.
O2N
O
HDNIB =
HO
I
O
S
NO2
O
DNs = 2,4-dinitrobenzenesulfonyl, R = H, CH3, CH2CH2CH3
Scheme
The results are summarized in the Table. When the re-
action was conducted by replacing HDNIB by HTIB11
and [hydroxy(4-nitrobenzenesulfonyloxy)iodo]benzene
(HNIB)9,10 respectively under the same reaction condi-
tions, aromatic carboxylic acids were obtained in poor
yields (entries 1 and 8). Therefore the greater reactivity
of -[(2,4-dinitrobenzene)sulfonyl]oxy ketone inter-
mediates12 should be associated with the higher leaving
ability of -[(2,4-dinitrobenzene)sulfonyl]oxy group at
nucleophilic substitution reactions. The oxidative cleav-
age reaction is likely to occur via nucleophilic substitution
of -ODNs group in the initially formed -[(2,4-dinitro-
benzene)sulfonyl]oxy ketone by Bu4NIO4 followed by
cleavage reaction of the resultant -keto iodate ester inter-
mediates with periodate.13
As part of our effort to find utilization of reactive -orga-
nosulfonyloxy ketone intermediates, we now wish to re-
port on the oxidation of alkyl aryl ketones to aromatic
carboxylic acids. This method is based on initial -orga-
nosulfonyloxylation of ketones utilizing [hydroxy(2,4-
dinitrobenzenesulfonyloxy)iodo]benzene (HDNIB) and
subsequent oxidation of -[(2,4-dinitrobenzene)sulfo-
nyl]oxy ketone intermediates with tetrabutyl ammonium
periodate in one-pot experimental manipulations.8 The
required HDNIB was readily prepared in 90% yield by
the reaction of iodobenzene diacetate (20.0 mmol) and
2,4- dinitrobenzenesulfonic acid dihydrate (40.0 mmol) in
acetonitrile by modification of well-known standard pro-
cedure for the preparation of [hydroxy(tosyloxy)io-
In conclusion, an efficient method for the conversion of
alkyl aryl ketones to aromatic carboxylic acids has been
developed. On account of its efficiency and neutral reac-
tion conditions, present protocol should be served as a
valuable alternative over the existing methods for the car-
bon-carbon cleavage reactions of alkyl aryl ketones.
Synlett 2001, No. 10, 28 09 2001. Article Identifier:
1437-210X,E;2001,0,10,1563,1564,ftx,en;Y13101st.pdf.
© Georg Thieme Verlag Stuttgart · New York
ISSN 0936-5214