LETTER
1679
Synthesis of , -Dicarboxylic Acid Dimethyl Esters from Cycloalkanones
S
J
ynthesis
o
of
,
-Dica
r
n
boxylic Acid
g
Dimethyl Esters Chan Lee,* Chang Hoe Ku
Department of Chemistry, Chung-Ang University, Seoul 156-756, Korea
Fax +82(2)8254736; E-mail: jclee@cau.ac.kr
Received 30 July 2002
This method is based on the formation of -[(2,4-dini-
trobenzene)sulfonyl]oxy cycloalkanone intermediates,
which subsequently react with Oxone in the presence of
Abstract: Reaction of cycloalkanones with [hydroxy(2,4-dini-
trobenzenesulfonyloxy)iodo]benzene and subsequent treatment of
®
-
[(2,4-dinitrobenzene)sulfonyl]oxy cycloalkanone intermediates
®
p-toluenesulfonic acid (PTSA) under aqueous methanol
with Oxone and PTSA in MeOH–H O (6:1, v/v) solution provided
2
dicarboxylic acid dimethyl esters in high yields.
solution (Scheme 1). Initially, we have assumed that -
[
(2,4-dinitrobenzene)sulfonyl]oxy group is able to show
Key words: carboxylic acids, esters, ketones, oxidations, ring
opening
equivalent or superior reactivity for the oxidative ring
cleavage reactions as like the nitro functional group in -
nitrocycloalkanones.
There have been continuing interests in , -dicarboxylic
acid dimethyl esters due to their unique chemical proper-
ties and usefulness as synthetic intermediates for the var-
ious synthetic transformations. The , -dicarboxylic
acid dimethyl esters can be prepared by a variety of meth-
O
O
ODNs
HDNIB
1
CH3CN
(
)n
(
)n
1 h, 80 °C
ods which include the oxidative ring opening reaction of
1
,2
3
-
nitrocycloalkanones,
-halocycloalkanones, and ox-
Oxone R , PTSA
4
idation of -hydroxy cycloalkanones. Among these
methods, the oxidative cleavage reaction of -nitrocyloal-
kanones with potassium persulfate in methanolic sulfuric
acid solution has constituted the most valuable method for
the synthesis of , -dicarboxylic acid dimethyl esters.1
However, preparation of the -nitrocyloalkanone precur-
sors were found not to be straightforward involving sever-
al indirect pathways. Moreover, reported methods for the
preparation of -nitrocycloalkanones directly from cy-
cloalkanones have been very scarce and proved to be in-
MeOH-H2O (6:1, v/v)
1-2 h, 65 °C
O
OMe
O
(
)n
MeO
n = 0, 1, 2
DNs = 2,4-dinitrobenzenesulfonyl
5
Scheme 1
6
effective for practical applications. There has been little
attention made for direct conversion of cycloalkanones to
the corresponding , -dicarboxylic acid dimethyl esters.
In this context, to our best knowledge, reaction of cycloal-
In this regard, we examined the reactions of various -
(2,4-dinitrobenzene)sulfonyl]oxy cycloalkanones under
[
present reaction conditions in order to evaluate the utility
of -[(2,4-dinitrobenzene)sulfonyl]oxy group toward oxi-
dative ring cleavage reactions. As shown in the parenthe-
ses of Table 1, the reaction of -[(2,4-dinitro-
kanones with VO(OEt)Cl in the presence of molecular
2
oxygen is the only direct method reported for the prepara-
7
tion of , -dicarboxylic acid diethyl esters. Therefore,
the development of an improved method for the prepara-
tion of , -dicarboxylic acid dimethyl esters that involves
oxidative ring cleavage of cycloalkanones using reaction
intermediates other than -nitrocycloalkanones should be
a valuable progress.
®
benzene)sulfonyl]oxy cyclohexanones with Oxone in
the presence of p-toluenesulfonic acid under MeOH-H O
2
(
6:1, v/v) solution for 1–2 h at 65 °C provided corre-
sponding diesters in the excellent yields. The required
[(2,4-dinitrobenzene)sulfonyl]oxy cycloalkanones
-
Recently, we have described efficient methods for the were readily obtained and isolated in 65–75% yields by
conversion of carbonyl compounds to -arenesulfonyloxy following the procedures in the previously reported meth-
8
ketones. In an effort to expand the scope of chemical od, which utilized the reaction of cycloalkanones with
transformations involving -arenesulfonyloxy ketone in- [hydroxy(2,4-dinitrobenzenesulfonyl-oxy)iodo]benzene
termediates, we undertook a study for the oxidative ring (HDNIB, 1.2 equiv) in acetonitrile at reflux.8 The
a
-
cleavage reaction of -[(2,4-dinitrobenzene)sulfonyl]oxy [(2,4-dinitrobenzene)sulfonyl]oxy cycloalkanones were
cycloalkanones to , -dicarboxylic acid dimethyl esters. stable upon storage for several days at room temperature.
Being established synthetic utility of -[(2,4-dinitrobenz-
ene)sulfonyl]oxy cycloalkanones for the preparation of
diesters, we have conducted one-pot preparation of di-
esters from cycloalkanones without isolation of -orga-
Synlett 2002, No. 10, Print: 01 10 2002.
Art Id.1437-2096,E;2002,0,10,1679,1680,ftx,en;U04302ST.pdf.
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Georg Thieme Verlag Stuttgart · New York
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