Bi0/O2 as a new catalytic system for the oxidation of α-ketols, α-hydroxy acids and epoxides

Article abstract of DOI:10.1002/1099-0690(200102)2001:4<735::AID-EJOC735>3.0.CO;2-E

Bi⁰ has been used as a catalyst for the oxidative C-C bond cleavage under O₂ of α-ketols, α-hydroxy acids and terminal epoxides, to give the corresponding carboxylic acids. The results are compared to those obtained in similar oxidation reactions catalysed by Bi^III carboxylates. These reactions constitute the first example of the catalytic use of Bio in oxidation reactions, and the first evidence for a Bi^III/Bi⁰ redox couple under molecular oxygen.

Full text of DOI:10.1002/1099-0690(200102)2001:4<735::AID-EJOC735>3.0.CO;2-E

FULL PAPER
0
Bi /O as a New Catalytic System for the Oxidation of α-Ketols, α-Hydroxy
2
Acids and Epoxides
[
a]
[a]
[b]
[a]
Christine Coin, V e´ ronique Le Boisselier, Isabelle Favier, Mich e` le Postel, and
Elisabet Du n˜ ach*[
b]
Keywords: Bismuth / Cleavage reactions / Epoxides / α-Hydroxy acids / α-Ketols / Oxygen
Bi0 has been used as a catalyst for the oxidative C−C bond
cleavage under O of α-ketols, α-hydroxy acids and terminal
actions catalysed by BiIII carboxylates. These reactions con-
0
2
stitute the first example of the catalytic use of Bi in oxidation
III
0
epoxides, to give the corresponding carboxylic acids. The re- reactions, and the first evidence for a Bi /Bi redox couple
sults are compared to those obtained in similar oxidation re- under molecular oxygen.
Introduction
Results and Discussion
0
Oxidation of α-Ketols by Bi /O2
Although bismuth is regarded as a relatively nontoxic
heavy metal, its application to organic chemistry has been
rather neglected until recently, although it is likely now to
find new applications in low-toxicity catalytic processes.[
Organic chemistry involving bismuth derivatives has largely
The oxidation of α-ketol 1a in the presence of a catalytic
III
[20]
amount of Bi mandelate (5 mol-%)
in DMSO under
dioxygen (1 atm.) at 80 °C resulted, after 4.5 h, in a com-
plete conversion of the ketol, with the formation of benzoic
acid in 63% yield.[ The process involves the CϪC bond
cleavage of the α-ketol, with formation of carbon dioxide
1Ϫ3]
19]
[4Ϫ6]
been devoted to oxidation reactions,
particularly with
V
the use of stoichiometric amounts of Bi derivatives that
[
see Equation (1)].
V
III [7Ϫ9]
involve the redox couple Bi /Bi .
III
In the field of oxidation by Bi derivatives, a few medi-
ated processes have been described,[
10Ϫ12]
but their use in
[13Ϫ15]
oxidation catalysis has not yet been widely explored.
III
Recently, Bi has been reported as an efficient catalyst in
FriedelϪCrafts and other aldol-type reactions.[17]
Bismuth(III) carboxylates (α-hydroxycarboxylates, pyrid-
ine-carboxylates, salicylates) have recently been found to be
efficient catalysts for the oxidative CϪC bond cleavage of
[16]
[18]
epoxides to carboxylic acids in O /DMSO media.
Fur-
2
III
thermore, dioxygen was found to be the oxidant in the Bi
The addition of α-hydroxy ketones 1aϪc to a BiIII mand-
elate solution, in either DMF or DMSO, resulted in the
immediate formation of a grey-black precipitate. Under di-
oxygen, this precipitate rapidly dissolved and the medium
mandelate-catalysed oxidative transformation of α-ketols
into carboxylic acids.[ The Bi carboxylate/O system of-
19]
III
2
fers a different and new activity as an oxidizing system, as
compared with all previously described bismuth(V) or bis-
muth(III) reagents.
was kept homogeneous during the reaction. Under N2,
however, the initial precipitate persisted and could not be
We now present a novel extension of the catalytic oxida-
tion reactions of α-ketols, α-hydroxy acids and epoxides by
redissolved. This precipitate was filtered off and was ana-
0
0
lysed as Bi , recovered quantitatively (by EDTA com-
Bi under molecular oxygen and give some evidence for a
III
0
plexometry, 98Ϯ2% of Bi, IR).
Bi /Bi redox system. To the best of our knowledge, no
III
Under N , the reaction was stoichiometric in Bi (which
report in the literature deals with the oxidation of organic
2
0
resulted in black metallic bismuth) and produced the α-di-
compounds with the Bi /O catalytic system.
2
ketone. Under O , further CϪC bond cleavage occurred.
2
III
This bond cleavage was catalytic in Bi and presumably
III
0
0
III
involved the Bi /Bi redox couple with a Bi to Bi reox-
[
[
a]
b]
Laboratoire de Chimie Mol e´ culaire, Associ e´ au C.N.R.S., idation by dioxygen.
Universit e´ de Nice-Sophia Antipolis,
Parc Valrose, 06108 Nice Cedex 2, France
These observations prompted us to examine the behavi-
Laboratoire de Chimie Bio-organique, Associ e´ au C.N.R.S., our of α-hydroxy ketones in the presence of a catalytic
Universit e´ de Nice-Sophia Antipolis,
Parc Valrose, 06108 Nice Cedex 2, France
Fax: (internat.) ϩ 33-4 92 07 61 51
E-mail: dunach@unice.fr
0
amount of Bi . Thus, when 1a was added to a suspension
0
of commercially available Bi powder (relative molar ratio
0
10:1) in DMF under O at 80 °C, a slow dissolution of Bi
2
Eur. J. Org. Chem. 2001, 735Ϫ740

WILEY-VCH Verlag GmbH, 69451 Weinheim, 2001
1434Ϫ193X/01/0204Ϫ0735 $ 17.50ϩ.50/0
735

C. Coin, V. Le Boisselier, I. Favier, M. Postel, E. Du n˜ ach
FULL PAPER
Table 1. Bi-catalysed oxidation of α-ketols under O
2
(1 atm)
Entry
Substrate
Catalyst[a]
Additive (equiv.)
mandelic acid/Bi
Solvent, time
Product, Yield
0
0
1
2
3
4
5
6
7
8
9
1a
1a
1b
1a
1b
1a
1b
1c
1a
1b
1c
1b
Bi
Ϫ
DMF, 3 h
2a, 81%
2a, 71%
2b, 60%
2a, 84%
2b, 60%
2a, 63%
2b, 63%
2c, 66%
0
Bi
2:1
2:1
2:1
2:1
Ϫ
Ϫ
Ϫ
Ϫ
Ϫ
DMF, 3 h
0
Bi
DMF, 5 h
0
Bi
DMSO, 3 h
DMSO, 5 h
DMSO, 4.5 h
DMSO, 4.5 h
DMSO, 4.5 h
DMF, 4.5 h
DMF, 4.5 h
DMF, 51 h
DMSO, 4.5 h
0
Bi
III
Bi mandelate
III
Bi mandelate
III
Bi mandelate
III
Bi mandelate
2a, 58%
2b, 76%
2c, 50%
III
10
11
12
Bi mandelate
III
Bi mandelate
Ϫ
Ϫ
III
[b]
Bi mandelate
2b, Ͻ5%,ϩ Bi(0)
[
[
a]
b]
Reactions run with 5 mol-% Bi and with 10 mol-% of Bi catalysts at 80 °C. The Bi or Bi concentration was of 3Ϫ6·10Ϫ2 . Ϫ
III
0
0
III
Reaction runs under nitrogen.
was observed and, after 3 h reaction, benzoic acid was isol- yield and only ketol adducts of high molecular mass were
ated in 81% yield [Equation (1)]. No reaction occurred in formed.
0
III
the absence of O . This novel Bi -catalysed process involves
The Bi mandelate oxidation of 1aϪc under O in DMF
2
2
the oxidative CϪC bond cleavage of the α-ketol to the cor- afforded 2aϪc in 58, 76 and 50% yields, respectively. In this
III
responding carboxylic acid under molecular oxygen.
Bi -catalysed oxidation in DMF, dioxygen is the oxidant
III
In order to mimic better the related Bi mandelate ox- in the process and its consumption was measured in the
idation of the same substrates, the Bi /O oxidations were case of 1c as 1.5 mol O /mol of substrate. CO was the by-
0
2
2
2
carried out in the presence of added mandelic acid (relative product of the oxidation of 1b in DMF, as was established
0
molar ratio 1:Bi :mandelic acid of 10:1:2). The yields of from the quantitative precipitation of BaCO when bub-
3
carboxylic acid 2a and 2b were 71 and 60%, respectively. bling the gaseous effluents over a Ba(OH) solution.
2
Table 1 summarizes these results.
The comparison of yields in Table 1 should be taken with
The oxidation of α-hydroxy ketones could also be carried some caution, because the reaction times and the catalyst
0
out in DMSO. The Bi /O system in DMSO produced 2a concentrations were not the same in all the examples.
2
and 2b in 84 and 60% yield, respectively.
Our results indicate that oxidative cleavage by O of α-
2
In contrast, when metallic bismuth was added to a DMF hydroxy ketones in the presence of bismuth can be carried
III
0
or a DMSO solution at 80 °C under dioxygen but without out using either a Bi carboxylate or Bi .
the organic substrate, no apparent dissolution occurred.
After 4 h, Bi was filtered off and recovered quantitatively.
0
Bi-Catalysed Oxidations of Styrene Oxide
The medium also remained heterogeneous and no reaction
The oxidation of styrene oxide in the presence of a cata-
III
occurred when mandelic acid (2 equiv./Bi, which mimics the lytic amount of Bi mandelate in DMSO under dioxygen
stoichiometry of the BiIII mandelate complex ) was ad- (1 atm.) has been reported.
[20]
[18b]
he reaction, carried out at
ded. After 3.5 h at 80 °C, mandelic acid remained un- 80 °C, resulted after 4.5 h in complete conversion of the
0
changed and Bi could be recovered in 83% yield. However, epoxide, with the formation of benzoic acid in 58% yield.
0
as indicated, a catalytic oxidation involving Bi dissolution The process involves the CϪC bond cleavage of the epoxide
occurred when an α-ketol was added to the DMF solution and the incorporation of three oxygen atoms per epoxide
under O2.
Similar behaviour, with rapid formation of Bi upon ad-
molecule ([Equation (2)].
The same treatment under air (20 atm.) afforded 64% of
0
dition of α-hydroxy ketones 1 and its further dissolution carboxylic acid. DMSO was necessary for the reaction; no
III
when under O , was also observed for other Bi carb- epoxide conversion occurred with DMF as the solvent.
2
oxylates that we tested, such as Bi salicylate, Bi phthalate
or Bi pinacolate.
Here, again, when the same reaction was carried out un-
der N , a grey precipitate was formed; it could be filtered
2
For comparison, the behaviour of α-ketols in the pres- off and identified as metallic bismuth (IR, elemental ana-
III
0
ence of Bi catalysts was examined. Treatment of sub- lysis). No precipitate of Bi could be observed in other ep-
III
strates 1aϪc with Bi mandelate (5 mol-%) in DMSO un- oxide reactions, either under O or under air. Under N ,
2
2
der O resulted in the CϪC bond cleavage with the forma- benzoic acid was obtained from styrene oxide in only 8%
2
tion of the corresponding carboxylic acids 2aϪc in 63Ϫ66% yield, together with phenacyl alcohol (28%), which was pre-
yields (Table 1). The α-diketone (or α-ketoaldehyde) was an sumably formed from the direct DMSO oxidation of the
III
[21]
intermediate in this reaction. In the absence of Bi , no re- oxirane ring.
action occurred. Under N , less than 5% of 2b was formed The formation of Bi from Bi in reactions under N2
in the oxidation of 1b; starting 1b was recovered in 56% suggests that reduced bismuth species might be interme-
0
III
2
736
Eur. J. Org. Chem. 2001, 735Ϫ740

A New Catalytic System for the Oxidation of α-Ketols, α-Hydroxy Acids and Epoxides
FULL PAPER
diates in the catalytic oxidation reaction of epoxides under Table 2. Oxidation of styrene oxide catalysed by Bi or by BiIII
0
[a]
III
2
under O (1 atm)
dioxygen, and that Bi could be recycled under O2.
As mentioned in the case of α-hydroxy ketones, when me-
tallic bismuth was added to a DMSO solution containing
mandelic acid (as the additive) under dioxygen, no apparent
0
Bi dissolution occurred. However, catalytic oxidation and
0
Bi dissolution occurred in the presence of the epoxide.
0
Thus, when styrene oxide was added to a Bi /DMSO solu-
tion with mandelic acid (relative molar ratio 10:1:2) under
0
O at 80 °C, the solution slowly became homogeneous (Bi
2
dissolution), and benzoic acid was isolated in 48% yield
after 4.5 h [Equation (2)]. The yield of benzoic acid was
lower, but comparable to that obtained in the BiIII mandel-
ate oxidation (58%). No benzoic acid was formed in the
0
absence of Bi or in the absence of O or DMSO.
2
[
a]
Reactions were carried out in DMSO at 80 °C over 4.5 hours.
Ϫ [ In this example, 4-methylstyrene oxide was used as the sub-
b]
[c]
0
strate. Ϫ [ Bi was used in 10 mol-% ratio with respect to styrene
d]
[18c,18d]
III
oxide. Ϫ Yields taken from refs.
catalysed reactions (10 mol-%) run under the same conditions (1
atm O , DMSO, 80 °C, 2.5Ϫ4.5 h).
for comparison, in Bi -
2
any improvement in the final yield of benzoic acid on in-
creasing the additive concentration.
0
The Bi /O system with DMF as the solvent was not effi-
2
cient, and unchanged styrene oxide could be recovered
quantitatively, whether in the presence or the absence of
additive. DMSO was necessary for both the Bi and the
Bi epoxide oxidations. Our results indicate that the epox-
ide oxidation to carboxylic acids involves the system Bi or
0
III
Bi and Bi Oxidation of α-Hydroxy Acids
0
0
III
The use of the Bi /O system was extended to the oxidat-
2
0
ive cleavage of the CϪC bond of several α-hydroxy acids,
as shown in Equation (3).
III
Bi /O /DMSO, and that oxidants DMSO and O are both
2
2
necessary for the reaction, in contrast with the oxidation of
α-hydroxy ketones, for which O was the only oxidant re-
2
quired. We suggest that DMSO is necessary for the first
step of oxirane ring-opening in a Swern-type oxidation to a
[
22,23]
ketol,
and that dioxygen is needed for further oxidative
CϪC bond cleavage and for the recycling of the reduced
Several substituted aryl derivatives were oxidized to the
corresponding benzoic acid derivatives with good yields
bismuth species.
0
Styrene oxide oxidation by Bi /O /DMSO in the absence and selectivities. The oxidative cleavage reaction was carried
2
of mandelic acid resulted in poor reproducibility, with out at 125 °C, with DMSO or DMF as the solvents. The
0
yields of benzoic acid in the range of 0Ϫ52%.
Bi /O catalytic system was shown to be more efficient in
2
III
Several carboxylic acids, Bi complexes of which had the presence of acetic acid as the additive (1.5 equiv./Bi).
previously been prepared and tested in oxidation reac- Table 3 summarizes the results for Bi and Bi -catalysed
0
III
[
18c]
0
tions,
were used as additives in the Bi -catalysed oxida- oxidations of several α-aryl-α-hydroxy acids.
0
tion of styrene oxide in DMSO under oxygen. The results
The oxidation of 4-chloromandelic acid with Bi /O in
2
are presented in Table 2.
DMSO (entry 1) afforded 4-chlorobenzoic acid, with 98%
0
For Bi systems with salicylic, m-nitrosalicylic, phthalic selectivity and 56% conversion after 24 h. The alternative
or benzoic acids, as well as with mandelic acid, the yields use of Bi phthalate as the catalyst produced the carb-
III
(
37Ϫ50%) and the rate of the reactions were slightly lower oxylic acid with 99% selectivity and 68% conversion (entry
III
but in the same range as those of the corresponding Bi - 2). The same oxidation in DMF (entry 3) afforded 4-chloro-
catalysed oxidations (44Ϫ58%).
Bi /AcOH (1:3) was also an active catalytic system (entry
benzoic acid with 70% selectivity.
0
Excellent carboxylic acid selectivities were also obtained
0
8
), affording 40% of benzoic acid, although no clean reac- for the Bi /O oxidation of the 4-fluoro- or 4-trifluorome-
2
tion could be found with Bi(OAc)3 under our experi- thyl-substituted aromatic derivatives (entries 4,5), or with
mental conditions.
unsubstituted mandelic acid (entry 6) in DMSO. In DMF,
In the case of salicylic acid (entries 2, 3), the ratio of Bi0 oxidative cleavage occurred but the selectivities were lower.
to carboxylic acid was changed from 1:1 to 1:5, but without For comparison, in the case of entry 5 with DMF as solv-
Eur. J. Org. Chem. 2001, 735Ϫ740
737

C. Coin, V. Le Boisselier, I. Favier, M. Postel, E. Du n˜ ach
FULL PAPER
2
Table 3. Bi-catalysed oxidative cleavage of α-hydroxy acids under O (1 atm)
Entry
Substrate
Catalyst[a]
Additive
Solvent, time
Conversion
Product selectivity
0
1
2
3
4
5
6
7
4-ClϪC
4-ClϪC
4-ClϪC
6
6
6
H
H
H
H
4
4
4
Bi
AcOH
Ϫ
Ϫ
AcOH
AcOH
AcOH
AcOH
DMSO, 24 h
DMSO, 24 h
DMF, 48 h
DMSO, 24 h
DMSO, 24 h
DMSO, 24 h
DMSO, 6 h
56%
68%
100%
72%
97%
52%
77%
98%
99%
70%
97%
99%
90%
62%
III
Bi -phthalate
III
Bi -phthalate
0
4-FϪC
6
4
Bi
0
4-CF ϪC
3
6
H
4
Bi
III
C
6
H
5
Bi mandelate
III
4-MeO-C
6
H
4
Bi mandelate
[
a]
Reactions carried out with 10 mol-% Bi catalyst at 125 °C and 1.5 equiv. of additive/Bi0.
III
ent, 4-trifluoromethylbenzoic acid was obtained with 100%
conversion and 33% selectivity.
Under N , the same treatment of ketol 1b with Bi man-
2
delate (5 mol-%) afforded less than 5% of carboxylic acid
The CϪC cleavage reaction of the tested α-hydroxy acids 2b, and 56% of 1b could be recovered (DMSO, 80 °C, 4 h).
0
proceeded through the formation of the α-keto acid inter- Also, under N , treatment of ketols 1a or 1b with Bi (10
2
mediate, which, under specific reaction conditions, could be mol-%), with or without additive (mandelic acid, 20 mol-
isolated in several cases.
%) resulted in no oxidation (DMF or DMSO, 80 °C, 4 h)
The presence of an electron-donating substituent such as and in the complete recovery of the starting materials. Un-
methoxy on the aromatic ring also permitted the formation der O (1 atm), these same processes afforded carboxylic
2
of the corresponding carboxylic acid (entry 7), but with a acid 2a in 71Ϫ84% yield (DMF or DMSO, 80 °C, 3 h), and
selectivity of only 62%. The remaining by-product was 4- 2b in 60% yield (DMF or DMSO, 80 °C, 5 h).
methoxybenzaldehyde.
The catalytic oxidation of styrene oxide to benzoic acid
The oxidation of α-aryl-α-hydroxy acids to the corres- (10 mol-% catalyst) could be effected either by the system
III
0
ponding benzoic acids required more forcing reaction con- Bi /O2 in DMSO or by the system Bi /O /additive in
2
ditions (125 °C, 24 h) than those used for the oxidation of DMSO (additive ϭ carboxylic acid, see Table 2). Benzoic
III
α-ketols or aryl epoxides (80 °C, 4 h). Bi mandelate as acid yields of 32Ϫ58% were obtained.
catalyst or mandelic acid as the additive could be therefore
be used in the oxidation of α-ketols or aryl epoxides with-
out decomposition.
III
The same reaction under N , catalysed by Bi in DMSO,
2
afforded only 8% of benzoic acid, together with a black
0
precipitate of Bi(0). Also, under N , the Bi /additive system
2
0
in DMSO produced no epoxide oxidation and no Bi dis-
Mechanistic Considerations
solution.
III
0
Our results indicate that the oxidative cleavage by O of
In summary: Under O , Bi - or Bi -catalysed oxidation
2
2
α-hydroxy ketones, epoxides and α-hydroxy acids in the of α-ketols, epoxides and α-hydroxy acids takes place with
III
presence of bismuth can be carried out using either a Bi - oxidative CϪC bond cleavage, whereas under N almost no
2
0
carboxylate or Bi (Scheme 1).
reactivity was observed for the same systems.
From a mechanistic point of view, one of the key steps
III
lies in the coordination of Bi to the α-hydroxy derivative
(
e.g., α-hydroxy ketone) in its hydroxy enolate form, fol-
lowed by a redox step in which the α-diketone is formed
III
I
and the Bi is formally reduced to Bi . We propose that
I
under O , this reduced Bi species is readily reoxidized to
Bi . Under nitrogen, a dismutation can occur into Bi ,
2
III
0
III
which precipitates as black, metallic bismuth, and Bi . The
Scheme 1. Involvement of BiIII-carboxylate and Bi in the catalytic activation and transfer of molecular oxygen in the reoxida-
0
oxidation of a substrate (S) (e.g. α-ketols, α-hydroxy acids or epox-
ides) under O
I
0
tion step of either the Bi intermediate or Bi remains uncer-
tain. However, α-diketones were found to be the interme-
diates in the oxidation of α-ketols and epoxides, and α-keto
acids were also found as intermediates in the oxidations of
α-hydroxy acids.
2
Comparing the experiments carried out with or without
O , we can summarize our results as follows: the oxidation
2
of α-ketols 1 can be carried out under O (1 atm) with a
2
III
0
0
catalytic amount (5Ϫ10 mol-%) of either Bi or Bi , with
It is noteworthy that the isolation of Bi from stoichi-
III
either DMF or DMSO as solvents (80 °C, 3Ϫ5 h). This ometric Bi oxidations under N does not rule out passage
2
I
I
treatment resulted in the oxidative CϪC bond cleavage of through Bi intermediate species. Bi complexes are very un-
the α-ketol, and in the formation of carboxylic acids 2 in stable, but their intermediate formation has been evoked for
yields of 50Ϫ84% ([Equation (1)]. The consumption of O2 several processes.[
24]
was measured, for the oxidation of 1c with BiIII mandelate,
A catalytic cycle for the oxidation of by BiIII is proposed
in Scheme 2.
as 1.5 mol of O per mol of substrate.
2
738
Eur. J. Org. Chem. 2001, 735Ϫ740

A New Catalytic System for the Oxidation of α-Ketols, α-Hydroxy Acids and Epoxides
FULL PAPER
in Table 1) at 80° C for 30 min. This was followed by the addition
of the α-ketol or the epoxide (3 mmol). The solution was main-
tained at 80 °C for α-ketols or epoxides and at 125 °C for α-hydroxy
1
acids. The reaction was followed by GC or by H NMR until com-
plete consumption of the substrate. Acidic hydrolysis using aqueous
0
.1 N HCl solution, diethyl ether extraction, treatment of the or-
ganic layer with aqueous 0.1 N NaOH solution until pH ϭ 12Ϫ14
was reached,and ether reextraction gave the neutral products of the
reaction. Acidification of the basic aqueous phase with 1 N HCl
solution to pH 1Ϫ2, followed by a final ether extraction, afforded
the carboxylic acids 2, which were precipitated using ether-pentane
1
mixtures and filtered off. The products were analysed by GC, H
1
3
and C NMR and mass spectroscopy, and their spectral data com-
pared to those of authentic samples.
The same procedure was used for BiIII-catalysed oxidations, with
5Ϫ10 mol-% of the catalyst.
Scheme 2. Mechanism of the oxidation of α-ketols
Several attempts were made to precipitate the complexes Acknowledgments
0
formed from the reaction of Bi and 1a in DMF under O ,
2
We thank CNRS and Rh oˆ ne Poulenc for financial support and the
French Ministry of Education for a Scholarship to C. C. and
V. L . B.
but no clean complex could be isolated. Studies on mechan-
istic aspects of the Bi /O catalytic system are currently un-
0
2
derway.
[
1]
N. Sax, R. J. Irving, in Dangerous Properties of Industrial Mat-
erials, Van Nostrand Reinhold, 1989.
L. D. Freedman, G. O. Doak, Chem. Rev. 1982, 82, 15Ϫ57.
H. Suzuki, T. Ikegami, Y. Matano, Synthesis 1997, 3, 249Ϫ267.
J. P. Kitchin, Organic Syntheses by Oxidation with Metal Com-
pounds, (Eds.: W. J. Mijs, C. R. H. I. de Jonge), chap. 15,
Plenum Press, New York, 1986.
[
[
[
2]
3]
4]
Conclusions
In conclusion, this work constitutes the first example of
0
oxidation reactions by molecular oxygen involving Bi as
0
the catalyst. We have shown that the Bi /O system was effi-
[5]
2
E. Du n˜ ach, M. Postel, Recent Res. Devel. Organomet. Chem.
1996, 1, 1Ϫ22.
cient for the oxidative CϪC bond cleavage of α-hydroxy
ketones, α-hydroxy acids and aryl epoxides to the corres-
ponding carboxylic acids. These oxidations could be carried
[
[
6]
M. Postel, E. Du n˜ ach, Coord. Chem. Rev. 1996, 115, 127Ϫ144.
7] [7a]
[7b]
W. Rigby, J. Chem. Soc. 1950, 1907Ϫ1913. Ϫ
F. R.
Hewgill, B. R. Kennedy, D. Kilpin, J. Chem. Soc. 1965,
III
0
[7c]
out independently using either the Bi /O or the Bi /O
2904Ϫ2914. Ϫ
C. J. R. Adderley, F. R. Hewgill, J. Chem.
2
2
[7d]
Soc., C 1968, 2770Ϫ2774. Ϫ
Chem. 1975, 40, 1515Ϫ1517.
E. Kon, E. McNelis, J. Org.
systems.
Oxidative cleavage of α-hydroxy ketones or α-hydroxy ac-
ids can be carried out either in DMF or in DMSO. How-
ever, the presence of DMSO is required for the oxidative
cleavage of epoxides, which can be effected using either Bi-
[8] [8a]
D. H. R. Barton, D. J. Lester, W. B. Motherwell, M. T. B.
[
8b]
Papoula, J. Chem. Soc., Chem. Commun. 1979, 705Ϫ707. Ϫ
D. H. R. Barton, D. J. Lester, W. B. Motherwell, M. T. B.
[
8c]
Papoula, J. Chem. Soc., Chem. Commun. 1980, 246Ϫ247. Ϫ
D. H. R. Barton, N. Y. Bhatnagar, J. P. Finet, J. Khamsi, W.
B. Motherwell, S. P. Stanforth, Tetrahedron 1987, 43, 323Ϫ332.
Ϫ [ D. H. R. Barton, J. P. Finet, C. Giannotti, F. Halley,
Tetrahedron 1988, 44, 4483Ϫ4494.
III
0
/
O /DMSO or Bi /O /DMSO systems.
2 2
8d]
III
0
The Bi /Bi redox couple has been proposed for the first
time in catalytic reactions involving dioxygen. To the best
of our knowledge, no catalytic cycle involving Bi /Bi in
oxidation reactions has yet been reported in the literature.
[9] [9a]
H. Firouzabadi, I. Mohammadpour-Baltork, Bull. Chem.
III
0
[9b]
Soc. Jpn. 1992, 65, 1131Ϫ1134. Ϫ
L. K. Truesdale, M. E.
[9c]
Reuman, J. Org. Chem. 1980, 45, 726Ϫ727. Ϫ
M. Kurihara, D. S. Watt, A. Demir, J. Org. Chem. 1993, 58,
R. Floresca,
Moreover, the possibility of using O as the oxidant opens
2
2196Ϫ2200.
[
[
10]
11]
new perspectives in the field of clean and catalytic oxida-
tion processes.
W. Rigby, J. Chem. Soc. 1951, 793Ϫ795.
E. M. Campi, G. B. Deacon, G. L. Edwards, M. D. Fitzroy, N.
Giunta, W. R. Jackson, R. Trainor, J. Chem. Soc., Chem. Com-
mun. 1989, 407Ϫ408.
V. A. Dodonov, T. I. ZinovЈeva, Metalloorg. Khim. 1993, 6,
375Ϫ376.
[
[
[
12]
13]
Experimental Section
D. H. R. Barton, J. P. Finet, W. B. Motherwell, C. Pichon,
General: The different BiIII-carboxylates were prepared from Bi
and the corresponding carboxylic acids, according to refs.
Other products were used as supplied. DMSO and DMF were dis-
Tetrahedron 1986, 42, 5627Ϫ5636.
2
O
3
14] [14a]
[
18c,20]
N. Komatsu, A. Taniguchi, M. Uda, H. Suzuki, Chem.
[14b]
Commun. 1996, 1847Ϫ1848. Ϫ
Suzuki, Chem. Lett. 1997, 1229Ϫ1230.
N. Komatsu, M. Uda, H.
tilled under vacuum in the presence of CaH
2
.
[15]
S. A. Tymonko, B. A. Nattier, R. S. Mohan, Tetrahedron Lett.
1
999, 40, 7657Ϫ7659.
0
General Procedure for Oxidations with Bi : Anhydrous DMSO or
DMF (5 mL) was stirred under oxygen (1 atm) in the presence of
commercial Bi0 powder (0.3 mmol) and in the absence or in the
presence of the desired additive (0.3 mmol or the equivalents used
[16]
J. R. Desmurs, M. Labrouill e` re, C. Le Roux, H. Gaspard, A.
Laporterie, J. Dubac, Tetrahedron Lett. 1997, 38, 8871Ϫ8874.
[17]
C. Le Roux, S. Mandrou, J. Dubac, J. Org. Chem. 1996, 61,
3885Ϫ3887.
Eur. J. Org. Chem. 2001, 735Ϫ740
739

C. Coin, V. Le Boisselier, I. Favier, M. Postel, E. Du n˜ ach
FULL PAPER
[
18] [18a]
[21] [21a]
[21b]
T. Zevaco, E. Du n˜ ach, M. Postel, Tetrahedron Lett. 1993,
T. Tsuji, Tetrahedron Lett. 1966, 2413Ϫ2414. Ϫ
B. M.
[18b]
3
4, 2601Ϫ2604. Ϫ
J. Organomet. Chem. 1994, 482, 119Ϫ123. Ϫ
Coin, E. Du n˜ ach, M. Postel, New J. Chem. 1997, 21, 495Ϫ502.
V. Le Boisselier, E. Du n˜ ach, M. Postel,
Trost, M. J. Fray, Tetrahedron Lett. 1988, 2163Ϫ2166.
A. J. Mancuso, D. Swern, Synthesis 1981, 165Ϫ175.
T. T. Tidwell, Synthesis 1990, 857Ϫ870.
[18c]
[22]
[23]
K. Kallal, C.
[
18d]
Ϫ
C. Coin, T. Zevaco, E. Du n˜ ach, M. Postel, Bull. Chim.
[24] [24a]
J. Lorberth, W. Massa, S. Wocaldo, I. Sarraje, S. H. Shin,
Soc. Fr. 1996, 133, 913Ϫ918.
[24b]
X. W. Li, J. Organomet. Chem. 1995, 485, 149Ϫ152. Ϫ
R.
[
[
19]
20]
V. Le Boisselier, C. Coin, M. Postel, E. Du n˜ ach, Tetrahedron
E. Dessy, T. Chivers, W. Kitching, J. Am. Chem. Soc. 1966, 88,
1
995, 51, 4991Ϫ4996.
[24c]
4
67Ϫ470. Ϫ
X. W. Li, J. Lorberth, W. Massa, S. Wocaldo,
III
2 2 2 3
Bi mandelate or [Bi(mand) ] O was prepared from Bi O and
J. Organomet. Chem. 1995, 485, 141Ϫ147.
mandelic acid in refluxing water according to: T. Zevaco, M.
Received April 4, 2000
Postel, React. Inorg. Met-Org. Chem. 1992, 22, 289Ϫ297.
[O00220]
740
Eur. J. Org. Chem. 2001, 735Ϫ740