Cerium-Catalyzed Reaction of β-Dicarbonyl Compounds with Styrene and Atmospheric Oxygen

Article abstract of DOI:10.1002/ejoc.200300439

The cerium-catalyzed C-C coupling reaction of carbo- and heterocyclic β-dicarbonyl compounds 1 with styrenes 4, using oxygen (air) as the oxidant, at ambient temperature, is reported. The reaction afforded a mixture of diastereoisomeric hydroperoxides 5 w

Full text of DOI:10.1002/ejoc.200300439

FULL PAPER
Cerium-Catalyzed Reaction of β-Dicarbonyl Compounds with Styrene and
Atmospheric Oxygen
[a]
[a]
[a]
[a]
Jens Christoffers,* Thomas Werner, Wolfgang Frey, and Angelika Baro
Keywords: Cerium / CϪC coupling / Peroxides / Oxidation
The cerium-catalyzed C−C coupling reaction of carbo- and
heterocyclic β-dicarbonyl compounds 1 with styrenes 4, us-
ing oxygen (air) as the oxidant, at ambient temperature, is
reported. The reaction afforded a mixture of diastereoisom-
eric hydroperoxides 5 which could be transformed into the
unique dioxo compounds 6 by disproportionation of the per-
oxo function under treatment with acetyl chloride/pyridine.
( Wiley-VCH Verlag GmbH & Co. KGaA, 69451 Weinheim,
Germany, 2003)
Introduction
Of course, it has been known for a long time that β-dicar-
bonyl compounds can be oxidized to their α-radicals with
IV
III
Atmospheric oxygen (air) represents the oxidant of stoichiometric amounts of Ce or Mn reagents such as
choice from an economical and ecological point-of-view, CAN or Mn(OAc) , and these radicals have been investi-
3
[
3]
and this makes procedures using oxygen highly attractive. gated intensively in CϪC bond forming reactions. For ex-
For example, we recently published a novel cerium-cata- ample, CAN has been utilized for oxidative dimerizations
[
4]
[5]
[6]
lyzed α-hydroxylation of cyclic β-dicarbonyl compounds 1 of malonates, as well as for inter- and intramolecular
[1]
IV
with O (Scheme 1). For this reaction we assume a Ce
conversions of β-dicarbonyl compounds with olefins. Anal-
2
diketonate complex 3a to be an intermediate, which may, in ogously, α-radicals generated from β-dicarbonyls and
[
7]
the sense of a ligand-to-metal charge transfer, also be re- Mn(OAc) react with olefins to give lactones and lactams.
3
III
garded as a Ce complex 3b with a radical β-diketon-α-yl Intramolecular insertion of these radicals has been applied
ligand. For the system shown in Scheme 1 with catalytic to the preparation of various β-lactams, higher lactams,
[
8]
III
IV
[9]
amounts of the cerium salt, a re-oxidation of Ce to Ce
and spirolactams. The Mn(OAc) -mediated reaction of β-
oxo esters with enol ethers is of particular interest, since
the products bear a 1,4-dicarbonyl motif. This structural
motif is commonly accessible only by the application of an
umpolung strategy or the transformation of furan deriva-
tives, and is useful in the preparation of annulated cyclo-
3
[2]
by O seems to be reasonable.
2
[
10]
[
11]
pentenone derivatives. All the literature referenced so far
IV
III
has used stoichiometric amounts of Ce or Mn reagents.
The re-oxidation of a Mn- or Ce-catalyst with molecular
oxygen under the reaction conditions seems to be a highly
attractive goal in terms of atom economy. And indeed, the
catalytic reaction of β-dicarbonyl compounds with olefins
and O in the presence of sub-stoichiometric amounts of
2
Mn(OAc) has been reported. Endoperoxidic products (1,2-
3
dioxane derivatives) are obtained in this reaction as the re-
[
12]
sult of a formal [2ϩ2ϩ2]-cycloaddition process.
How-
ever, the yields of these products only reach an acceptable
level in the cases of disubstituted olefins. Optimal results
are achieved using 1,1-diaryl-substituted alkenes, whereas
Scheme 1. Cerium-catalyzed α-hydroxylation of β-dicarbonyl com-
pound 1a proceeding via the assumed intermediate 3a/3b
[
13]
simple olefins like styrene give low yields.
Applying a
II
II
Mn ϪCo catalyst system, though, gives satisfying results
in the reaction of β-dicarbonyl compounds with simple al-
[
a]
Institut für Organische Chemie der Universität Stuttgart,
Pfaffenwaldring 55, 70569 Stuttgart, Germany
Fax: (internat.) ϩ 49-711-6854269
[14]
kenes and oxygen.
In this case, almost no by-products
with oxygen incorporation (for example, as hydroxy or per-
oxo functionalities) are formed. The use of catalytic
E-mail: jchr@po.uni-stuttgart.de
Eur. J. Org. Chem. 2003, 4879Ϫ4886
DOI: 10.1002/ejoc.200300439
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4879

J. Christoffers, T. Werner, W. Frey, A. Baro
FULL PAPER
amounts of cerium compounds and O as the re-oxidizing
The reaction conditions were optimized in the reaction
2
agent has been reported so far in only one case, resulting, of 1a with both 4a and 4b: to suppress the formation of the
in the cases of monosubstituted olefins such as styrene, α-hydroxylated product 2 in favour of the CϪC coupling
once again, in low yields of dihydrofuran products.[ Here- reaction, the conversion was performed under atmospheric
15]
in, we wish to report our results on CϪC coupling reactions oxygen instead of 1 atm O and a twofold excess of the
2
of styrenes 4 and cyclic and heterocyclic β-dicarbonyl com- olefin, while again, 2-propanol was found to be the opti-
pounds 1 with air as the oxidant, using only a catalytic mal solvent.
amount of the cerium salt CeCl ·7H O. This reaction gives
In the same manner, the five-membered heterocyclic β-
3
2
endoperoxidic 1,2-dioxane derivatives as products, and is dicarbonyl compounds 1d,e reacted with styrenes 4a,b to
analogous to the process using stoichiometric amounts of give the addition products 5gϪ5j and 6g,i (Scheme 2). The
III
IV [12,13]
Mn and Ce .
results are listed in Table 1.
In nearly all cases, the donors 1 were completely con-
sumed in the reaction. The reaction of 1 and styrene (4a)
afforded the α-hydroxylation products 2 and the dioxo de-
rivatives 6 as by-products. The reaction of the precursor
lactam 1e, however, gave the dioxo lactam 6i as the major
product in 45 % yield, as well as the CϪC coupling product
Results and Discussion
Cyclic β-oxo esters 1aϪc reacted with styrene (4a) and α-
methylstyrene (4b) in the presence of a cerium-catalyst and
atmospheric oxygen, to give the CϪC coupling products
5i (5 %) (Table 1).
5aϪf and 6a,c (Scheme 2, Table 1).
As depicted in Scheme 2, the hydroperoxides 5 exist in
their endoperoxidic hemiketal forms; monocyclic hydroper-
oxides could not be detected. Four diastereoisomers may be
expected for three stereocenters, and indeed, in case of the
seven-membered ring product 5f, four diastereomers were
detected. However, with the exceptions of 5e, 5h (three dia-
stereoisomers) and 5d, 5i (one diastereomer), in general,
two diastereoisomers were observed. In case of the lactone-
derived hydroperoxides 5g and 5h, the two diastereoisomers
could be separated by column chromatography on silica gel.
While the diastereomers of 5g were obtained in a 1:1 ratio,
two diastereomers of 5h were isolated in a ratio of 7:1 with
a trans-configured isomer as the major product, as proved
by the X-ray crystal structure. Crystallization of both dia-
stereoisomers of 5g and 5h from dichloromethane gave sin-
gle crystals which were suitable for X-ray crystallographic
[
16]
analysis (Figure 1 and Figure 2).
The relative configuration of both diastereomers of 5g
demonstrates a CϪC bond-formation without any stereo-
selectivity: the lactone and the phenyl group are arranged
either in the relative cis- (Figure 1, a) or the relative trans-
configuration (Figure 1, b). In case of 5h, however, the
trans-configured isomer (Figure 2, b) dominates the cis-iso-
Scheme 2. Cerium-catalyzed CϪC coupling reaction of β-dicar-
bonyl compounds 1aϪ1e and styrenes 4a,b with oxygen as oxidant;
3 2
reagents and conditions: (a) 1 (1 equiv.), 4 (2 equiv.), CeCl ·7H O
(0.05 equiv.), iPrOH, 23 °C, 16 h, air; for details see Table 1
Table 1. CeIII-catalyzed reaction of dicarbonyls 1 and styrenes 4 with atmospheric oxygen as oxidant
Donor
Olefin
Hydroperoxide
Yield (%)
5
R
X
Y
n
Yield (%)
dr
6
2
1a
1a
1b
1b
1c
1c
1d
1d
1e
1e
4a
4b
4a
4b
4a
4b
4a
4b
4a
4b
a
b
c
d
e
f
H
Me
H
Me
H
Me
H
Me
H
Me
CH
CH
CH
CH
CH
CH
O
O
NBn
NBn
2
2
2
2
2
2
OEt
OEt
OEt
OEt
OMe
OMe
Me
Me
Me
Me
0
0
1
1
2
2
Ϫ
Ϫ
Ϫ
Ϫ
68
87
50
42
54
53
64
73
5
62:38
64:36
50:50
100
38:35:27
38:25:23:14
54:46
71:10:19
100
a
Ϫ
c
Ϫ
e
Ϫ
g
Ϫ
i
Ϫ
4
Ϫ
1
Ϫ
n. d.[
Ϫ
8
Ϫ
a
a
b
3
5
25
25
46
17
18
n. d.
n. d.
n. d.
b
a]
c
c
d
d
e
e
g
h
i
[
[
[
a]
a]
a]
45
Ϫ
j
52
60:40
[
a]
n. d. ϭ not detected.
4880
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
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Eur. J. Org. Chem. 2003, 4879Ϫ4886

Cerium-Catalyzed Reaction of β-Dicarbonyl Compounds
FULL PAPER
mer (Figure 2, a) (trans:cis ϭ 7:1). Also, the crystallo-
graphic data of the two diastereomers of 5c confirm the cis/
trans configuration, but unfortunately, due to low crystal
quality in the case of the cis-isomer, the data cannot be
published. The remarkably high selectivity in the reversible
formation of the hemiacetalic, anomeric centers can be ex-
plained by stereoelectronic effects, which are common in
carbohydrate chemistry, and by the presence of intramo-
lecular hydrogen bonds.
The transformation of the epimeric mixtures of the endo-
peroxides 5 to unique products is, of course, a fundamental
issue. As shown in Scheme 3 for peroxide 5a, we succeeded
in converting the styrene-derived products 5 by treatment
with acetyl chloride (AcCl)/pyridine in dichloromethane
(path b). An excess of acetyl chloride mediates the dispro-
portionation of the peroxo function in 5a to give ketone 6a,
which was isolated in 78 % yield.
Figure 1. ORTEP view of the diastereoisomers of hydroperoxide
Scheme 3. Preparation of ketone 6a from 1a via the diastereomeric
mixture of hydroperoxide 5a; reagents and conditions: (a) 4a (2
5
g; (a) relative cis-configuration and (b) relative trans-configuration
of the lactone and phenyl group
3 2
equiv.), CeCl ·7H O (5 mol %), iPrOH, 23 °C, air; (b) AcCl (2
2 2
equiv.), pyridine (2 equiv.), CH Cl , 23 °C, 20 h
Conclusion
CϪC coupling reactions are fundamental to the con-
struction of carbon skeletons. We report, for the first time, a
synthetically applicable oxidative coupling of β-dicarbonyl
compounds 1 with olefins 4. In contrast to other known
procedures that require stoichiometric amounts of cerium,
manganese or cobalt salts, the presented conversion pro-
ceeds under catalysis with the inexpensive and non-toxic ce-
rium salt CeCl ·7H O, using atmospheric oxygen as oxidant
3
2
at ambient temperature. The mixtures of diastereoisomeric
hydroperoxides 5 obtained disproportionate to give dioxo
esters 6, in a reaction mediated by acetyl chloride/pyridine.
Dioxo derivatives 6 are of significant synthetic interest, due
to their 1,4-dicarbonyl structural motif, whose synthesis
usually requires the application of an umpolung strategy.
Experimental Section
General: The following compound was prepared according to lit-
erature procedures: 1e.[ All other starting materials are commer-
cially available. Column chromatography was carried out using
1b]
Merck SiO 60 with hexanes (PE, b.p. 40Ϫ60 °C), and EtOAc (EA)
2
13
as eluents. C NMR multiplicities were determined with DEPT
experiments.
General Procedure for the Cerium-Catalyzed Hydroperoxide Forma-
tion: The respective substrate 1 (1 equiv.) was added to a mixture
Figure 2. ORTEP view of the diastereoisomers of hydroperoxide
of CeCl
3 2
·7H O (0.05 equiv.) and the respective olefin 4 (2 equiv.)
5
h; (a) relative cis-configuration and (b) relative trans-configuration
of the lactone and phenyl group
in iPrOH (ca. 0.5 mL/1.6 mmol 1), and the reaction mixture was
Eur. J. Org. Chem. 2003, 4879Ϫ4886
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4881

J. Christoffers, T. Werner, W. Frey, A. Baro
FULL PAPER
stirred at 23 °C for 16 h under atmospheric oxygen. After removal
of all volatile materials under vacuum, the residue was filtered
fraction, alcohol 2a was obtained (R
f
ϭ 0.17, 14 mg, 0.081 mmol,
5 %). Diastereomer A: H NMR (300 MHz, CDCl ): δ ϭ 0.91 (t,
J ϭ 7.2 Hz, 3 H, CH ), 1.57 (s, 3 H, CH ), 1.77Ϫ1.92 (m, 3 H),
1
3
through or chromatographed on SiO
2
(PE/EA) to yield the prod-
3
3
ucts 5.
1.95Ϫ2.13 (m, 2 H), 2.11 (d, J ϭ 14.0 Hz, 1 H), 2.20Ϫ2.30 (m, 1
H), 2.81 (d, J ϭ 14.0 Hz, 1 H), 3.19 (dq, J ϭ 10.8, J ϭ 7.2 Hz, 1
H), 3.70 (dq, J ϭ 10.7, J ϭ 7.2 Hz, 1 H), 7.18Ϫ7.23 (m, 1 H, Ph),
Ethyl
1-Hydroxy-4-phenyl-2,3-dioxabicyclo[4.3.0]nonane-6-car-
1
3
1
boxylate (5a): According to the General Procedure, 1a (249 mg, 7.25Ϫ7.35 (m, 5 H, Ph and OH) ppm. C{ H} NMR (63 MHz,
1
.59 mmol), CeCl
3
·7H
2
O (30 mg, 0.081 mmol), and 4a (334 mg,
3 3 2 3 2
CDCl ): δ ϭ 13.50 (CH ), 20.08 (CH ), 30.03 (CH ), 35.50 (CH ),
3
.21 mmol) in iPrOH (0.5 mL) were converted. Filtration through 36.10 (CH ), 42.80 (CH ), 49.61 (C), 61.00 (CH ), 81.36 (C), 111.56
2
2
2
a short column of SiO
sisting of diastereomers A and B of 5a in a ratio of 62:38 (315 mg,
2
(PE:EA, 10:1) gave a crude fraction con- (C), 124.93 (CH), 126.95 (CH), 127.98 (CH), 143.53 (C), 176.33
(C) ppm. IR (ATR): ν˜ ϭ 3328 (br. s), 2968 (m), 1692 (s), 1443 (s),
Ϫ1
1.08 mmol, 68 %), alcohol 2a (7 mg, 0.04 mmol, 3 %), and ketone 1369 (m), 1339 (m), 1300 (m), 1203 (m), 1113 (m) cm . MS (FAB,
ϩ
ϩ
6
a (17 mg, 0.062 mmol, 4 %). By repeated chromatography (SiO
ϭ 0.25) and 6a (R ϭ 0.22), and
ϭ 0.19) and B (R ϭ 0.26) were completely (5), 121 (14), 73 (22). C H O (306.35): calcd. C 66.65, H 7.24;
2
,
2
glycerol): m/z (%) ϭ 307 (61) [MH ], 289 (25) [MH Ϫ H O], 271
ϩ
PE:EA, 5:1), by-products 2a (R
diastereomer A (R
separated. Diastereomer A: H NMR (500 MHz, CDCl
f
f
2 2
(38), 243 (31), 215 (100) [MH Ϫ H O Ϫ CO Et], 195 (10), 147
f
f
1
7
22
5
1
1
3
): δ ϭ 1.29
found C 66.63, H 7.24. Diastereomer B: H NMR (300 MHz,
), 1.88Ϫ2.02 CDCl ): δ ϭ 1.36 (t, J ϭ 7.0 Hz, 3 H, CH ), 1.40 (s, 3 H, CH ),
(t, J ϭ 7.1 Hz, 3 H, CH
3
), 1.75Ϫ1.86 (m, 1 H, CH
2
3
3
3
(
2
4
m, 3 H, CH ), 2.17Ϫ2.27 (m, 2 H, CH
2
2
), 2.30Ϫ2.37 (m, 1 H, CH
2
), 1.44Ϫ1.55 (m, 1 H), 1.65Ϫ1.77 (m, 2 H), 1.85Ϫ1.92 (m, 1 H),
1.97Ϫ2.03 (m, 1 H), 2.06Ϫ2.13 (m, 1 H), 2.39 (d, J ϭ 14.0 Hz, 1
), 5.26 (dd, J ϭ 2.5, J ϭ 11.9 Hz, 1 H, H), 2.70 (d, J ϭ 14.0 Hz, 1 H), 4.24Ϫ4.34 (m, 2 H), 6.06 (br. s, 1
.67 (dd, J ϭ 11.9, J ϭ 14.3 Hz, 1 H, CH
.18Ϫ4.25 (m, 2 H, CH
2
), 4.15 (br. s, 1 H, OH),
2
13
1
CH), 7.32Ϫ7.40 (m, 5 H, CH) ppm. C{ H} NMR (63 MHz, H), 7.26Ϫ7.30 (m, 1 H), 7.36Ϫ7.39 (m, 2 H), 7.46Ϫ7.47 (m, 2 H)
1
3
1
CDCl
5.13 (CH
CH), 128.60 (CH), 128.85 (CH), 137.43 (C), 174.57 (C) ppm. IR (C), 61.52 (CH ), 81.03 (C), 109.89 (C), 124.69 (CH), 126.87 (CH),
3
): δ ϭ 14.06 (CH
3
), 19.30 (CH
2
), 31.61 (CH
2
), 32.50 (CH
2
),
3 3
ppm. C{ H} NMR (63 MHz, CDCl ): δ ϭ 14.14 (CH ), 19.95
3
2
), 52.69 (C), 61.43 (CH
2
), 78.58 (CH), 108.37 (C), 127.08 (CH ), 29.19 (CH ), 34.59 (CH ), 36.15 (CH ), 38.90 (CH ), 51.18
2
3
2
2
2
(
(
2
film): ν˜ ϭ 3352 (br. s), 1708 (s), 1255 (m), 1177 (m), 1160 (m),
17 22 5
128.32 (CH), 146.41 (C), 176.47 (C) ppm. C H O (306.35): calcd.
Ϫ1
1
2
2
6
154 (m), 1102 (m), 1044 (m) cm . MS (FAB, glycerol): m/z (%) ϭ C 66.65, H 7.24; found C 66.50, H 7.19. The data of 2a were in
ϩ ϩ ϩ
[1b]
93 (75) [MH ], 275 (74) [M Ϫ H
29 (40), 201 (100), 153 (64), 105 (15). C16
5.74, H 6.90; found C 65.52, H 6.90. Diastereomer B: H NMR Ethyl
): δ ϭ 1.38 (t, J ϭ 7.3 Hz, 3 H, CH
), 1.74Ϫ1.89 boxylate (5c): According to the General Procedure, 1b (267 mg,
), 1.97Ϫ2.01 (m, 1 H, CH ), 1.97 (dd, J ϭ 10.7, J ϭ
1.57 mmol), CeCl ·7H O (30 mg, 0.081 mmol), and 4a (331 mg,
4.1 Hz, 1 H, CH ), 2.24Ϫ2.36 (m, 2 H, CH
), 2.55 (dd, J ϭ 5.2, 3.18 mmol) in iPrOH (0.5 mL) were converted. Filtration through
J ϭ 14.1 Hz, 1 H, CH ), 4.20Ϫ4.35 (m, 2 H, CH
), 5.15 (dd, J ϭ a short column of SiO (PE:EA, 10:1) gave a crude fraction con-
.2, J ϭ 10.7 Hz, 1 H, CH), 6.20 (s, 1 H, OH), 7.29Ϫ7.40 (m, 5 H, sisting of diastereomers A and B of 5c in a ratio 1:1 (240 mg,
2
O], 259 (82) [M Ϫ H
2 2
O ], accordance with the literature.
(292.33): calcd. C
20 5
H O
1
1-Hydroxy-4-phenyl-2,3-dioxabicyclo[4.4.0]decane-6-car-
(
(
500 MHz, CDCl
m, 3 H, CH
3
3
2
2
3
2
1
2
2
2
2
2
5
13
1
CH) ppm. C{ H} NMR (63 MHz, CDCl
3
): δ ϭ 14.23 (CH
), 37.18 (CH
), 51.74 (C), tone 6c (5 mg, 0.02 mmol, 1 %). By chromatography (SiO
), 79.50 (CH), 111.07 (C), 125.98 (CH), 128.19 (CH), 5:1), by-products 2b (R
3
),
0.785 mmol, 50 %), alcohol 2b (68 mg, 0.39 mmol, 25 %) and ke-
, PE:EA,
2
6
1
0.01 (CH
1.77 (CH
28.67 (CH), 140.38 (C), 175.72 (C) ppm. C16
2
), 34.95 (CH
2
), 35.54 (CH
2
2
2
f
ϭ 0.19) and 6c (R ϭ 0.23) were removed,
f
ϭ 0.32) and B (R ϭ 0.15) were separated
f
2
H
20
O
5
(292.33): calcd. and diastereomer A (R
f
1
C 65.74, H 6.90; found C 65.59, H 6.94. Ketone 6a: H NMR completely and obtained as colorless solids. Diastereomer A: M.p.
1
(300 MHz, CDCl
3
): δ ϭ 1.24 (t, J ϭ 7.1 Hz, 3 H), 2.03Ϫ2.17 (m, 118 °C. H NMR (500 MHz, CDCl
H), 2.53Ϫ2.69 (m, 3 H), 3.48 (d, J ϭ 18.6 Hz, 1 H), 3.86 (d, J ϭ H, CH ), 1.51Ϫ1.65 (m, 2 H, CH ), 1.71Ϫ1.82 (m, 4 H, CH
8.6 Hz, 1 H), 4.17 (q, J ϭ 7.1 Hz, 2 H), 7.43Ϫ7.49 (m, 2 H),
(dt, J ϭ 13.4, J ϭ 4.8 Hz, 1 H, CH ), 2.43 (dd, J ϭ 2.4, J ϭ
.55Ϫ7.60 (m, 1 H), 7.93Ϫ7.97 (m, 2 H) ppm. 13C{ H} NMR 14.2 Hz, 1 H, CH
), 2.45Ϫ2.55 (m, 1 H, CH ), 2.55 (dd, J ϭ 11.7,
): δ ϭ 14.00 (CH ), 19.86 (CH ), 33.40 (CH ),
J ϭ 14.2 Hz, 1 H, CH ), 4.24Ϫ4.31 (m, 1 H, CH ), 4.34Ϫ4.40 (m,
), 43.48 (CH ), 57.47 (C), 61.66 (CH
), 128.11 (CH), 1 H, CH ), 5.13 (dd, J ϭ 2.4, J ϭ 11.6 Hz, 1 H, CH), 7.25Ϫ7.26
28.65 (CH), 133.47 (CH), 136.31 (C), 170.71 (C), 196.74 (C),
(m, 1 H, CH), 7.32Ϫ7.39 (m, 5 H, CH, OH) ppm. C{ H} NMR
15.11 (C) ppm. IR (film): ν˜ ϭ 2980 (m), 1755 (s), 1721 (s), 1684 (63 MHz, CDCl
), 33.46 (CH
3
): δ ϭ 1.35 (t, J ϭ 7.0 Hz, 3
3
1
7
3
2
2
), 2.03
2
1
2
2
(125 MHz, CDCl
3
3
2
2
2
2
3
1
2
(
1
7.76 (CH
2
2
2
2
1
3
1
3
): δ ϭ 14.10 (CH
3
), 20.18 (CH
2
), 22.57 (CH
2
),
),
s), 1451 (m), 1401 (m), 1359 (m), 1285 (m), 1224 (s), 1186 (m), 30.45 (CH
2
2
), 35.76 (CH
2
), 48.44 (C), 61.99 (CH
2
Ϫ1
153 (m), 1105 (m), 1039 (m), 1001 (m) cm . MS (CI, CH
4
): m/z
81.51 (CH), 102.79 (C), 126.68 (CH), 128.63 (CH), 128.72 (CH),
ϩ
ϩ
ϩ
(%) ϭ 274 (34) [M ], 257 (21), 229 [M Ϫ OEt], 201 [M
Ϫ
137.54 (C), 177.71 (C) ppm. IR (ATR): ν˜ ϭ 3361 (br. s), 2931 (m),
CO
2
Et], 183 (5), 155 (17), 105 (53), 91 (7), 77 (8). HRMS calcd. 1706 (s), 1446 (m), 1278 (m), 1238 (s), 1174 (s), 1085 (m), 1025 (m),
ϩ
Ϫ1
ϩ
for C16
H
18
O
4
: 274.1205; found 274.1205 [M ]. C16
H
18
O
4
(274.31):
1001 (m) cm . MS (FAB, glycerol): m/z (%) ϭ 307 (16) [M ], 289
ϩ
calcd. C 70.06, H 6.61; found C 69.57, H 6.62. The data of 2a were (57) [M Ϫ H
2
O], 273 (100), 243 (6), 215 (16), 199 (22), 195 (48),
(306.15): calcd. C
in accordance with the literature.[
1b]
22 5
170 (6), 123 (12), 105 (15), 75 (5). C17H O
1
66.65, H 7.24; found C 66.79, H 7.15. Diastereomer B: H NMR
Ethyl 1-Hydroxy-4-methyl-4-phenyl-2,3-dioxabicyclo[4.3.0]nonane-
(500 MHz, CDCl
3
): δ ϭ 1.28 (t, J ϭ 7.1 Hz, 3 H, CH
), 1.82Ϫ1.93 (m, 3 H, CH
), 2.65 (dd, J ϭ 11.9, J ϭ 14.0 Hz, 1 H,
), 4.15Ϫ4.25 (m, 3 H, CH , OH), 5.40 (dd, J ϭ 2.4, J ϭ
11.9 Hz, 1 H, CH), 7.31Ϫ7.39 (m, 5 H, CH) ppm. C{ H} NMR
(63 MHz, CDCl ): δ ϭ 14.11 (CH ), 22.02 (CH ), 22.54 (CH ),
31.11 (CH ), 34.06 (CH ), 35.82 (CH ), 48.31 (C), 61.22 (CH ),
78.53 (CH), 99.30 (C), 127.12 (CH), 128.59 (CH), 128.88 (CH),
.23, 153 mg, 0.499 mmol, 31 %) as a colorless oil. In the third 137.58 (C), 174.71 (C) ppm. C17 (306.15): calcd. C 66.65, H
3
), 1.47Ϫ1.57
6
-carboxylate (5b): According to the General Procedure, 1a
254 mg, 1.63 mmol), CeCl ·7H O (30 mg, 0.081 mmol), and 4b 2.23Ϫ2.31 (m, 2 H, CH
386 mg, 3.27 mmol) in iPrOH (0.5 mL) were converted. Filtration CH
and subsequent chromatography (SiO , PE:EA, 5:1)
gave three fractions. The first fraction contained diastereomer A of
(m, 2 H, CH
2
), 1.63Ϫ1.69 (m, 2 H, CH
2
2
),
(
(
3
2
2
2
2
1
3
1
through SiO
2
2
3
3
2
2
5
6
0
b (R
f
ϭ 0.38, 281 mg, 0.917 mmol, 56 %) as colorless crystals, m.p.
2
2
2
2
6 °C. The second fraction contained diastereomer B of 5b (R
f
ϭ
22 5
H O
4882
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4879Ϫ4886

Cerium-Catalyzed Reaction of β-Dicarbonyl Compounds
FULL PAPER
7
(
(
2
1
.24; found C 66.47, H 7.18. Ketone 6c: M.p. 92 °C. 1H NMR
500 MHz, CDCl ): δ ϭ 1.27 (t, J ϭ 7.1 Hz, 3 H, CH
m, 4 H, CH ), 2.03Ϫ2.11 (m, 1 H, CH ), 2.44Ϫ2.49 (m, 1 H, CH
.51Ϫ2.56 (m, 1 H, CH ), 2.81Ϫ2.88 (m, 1 H, CH ), 3.39 (d, J ϭ (24). C17
7.4 Hz, 1 H, CHH), 3.57 (d, J ϭ 17.4 Hz, 1 H, CHH), 4.19Ϫ4.29 7.20. Diastereomer A: C{ H} NMR (125 MHz, CDCl
), 7.43Ϫ7.47 (m, 2 H, CH), 7.54Ϫ7.58 (m, 1 H, CH), 21.98 (CH ), 23.04 (CH ), 24.94 (CH ), 25.97 (CH ), 38.13 (CH
), 51.60 (C), 52.97 (CH ), 80.80 (CH), 102.88 (C), 126.39
), 40.55 (CH), 128.35 (CH), 128.57 (CH), 136.97 (C), 178.36 (C) ppm. Dia-
(s), 2862 (m), 1734 (s), 1699 (s), 1453 (s), 1212 (s), 1110 (m), 1017
Ϫ1
ϩ
3
3
), 1.74Ϫ1.88 (s) cm . MS (FAB, glycerol): m/z (%) ϭ 307 (18) [MH ], 289 (64)
ϩ
2
2
2
), [MH Ϫ H
2
O], 273 (100), 229 (2), 213 (25), 195 (14), 170 (2), 105
2
2
H O (306.15): calcd. C 66.65, H 7.24; found C 66.57, H
22 5
1
3
1
3
): δ ϭ
),
(
m, 2 H, CH
2
2
2
2
2
2
.94Ϫ7.97 (m, 2 H, CH) ppm. 13C{ H} NMR (63 MHz, CDCl
), 22.03 (CH ), 26.82 (CH ), 36.74 (CH
), 44.03 (CH ), 58.92 (C), 61.55 (CH ), 128.06 (CH), 128.54 stereomer B: C{ H} NMR (125 MHz, CDCl
CH), 133.12 (CH), 136.83 (C), 172.05 (C), 196.99 (C), 207.34 (C) 24.94 (CH ), 25.97 (CH ), 34.30 (CH ), 37.56 (CH
51.60 (C), 51.92 (CH
s), 1677 (s), 1455 (m), 1387 (m), 1369 (m), 1313 (m), 1225 (m), 128.60 (CH), 128.95 (CH), 140.68 (C), 173.82 (C) ppm. Dia-
1
): 38.97 (CH
7
3
2
3
δ ϭ 14.05 (CH
3
2
2
2
1
3
1
(CH
2
2
2
3
): δ ϭ 23.04 (CH
), 38.97 (CH
2
),
),
(
2
2
2
2
2
ppm. IR (KBr): ν˜ ϭ 2968 (m), 2958 (m), 2933 (m), 2866 (m), 1720
3
), 79.68 (CH), 102.88 (C), 127.17 (CH),
(
Ϫ1
1
1
183 (s), 1137 (m), 1071 (m), 1034 (m) cm . MS (EI, 70 eV): m/z
stereomer C: H NMR (500 MHz, CDCl
H, CH ), 1.69Ϫ1.82 (m, 2 H, CH ), 1.86 (ddd, J ϭ 2.1, J ϭ 6.8,
Et], 169 (100), 137 (21), 123 (40), 109 (15), 81 J ϭ 14.4 Hz, 1 H, CH ), 1.94Ϫ1.98 (m, 1 H, CH ), 2.01 (dd, J ϭ
: 289.1435 [MH ]; found 2.6, J ϭ 13.8 Hz, 1 H, CH ), 2.35Ϫ2.40 (m, 1 H, CH ), 2.45Ϫ2.51
), 2.64 (dd, J ϭ 11.4, J ϭ 13.8 Hz, 1 H, CH ), 3.68
), 4.24 (br. s, 1 H, OH), 5.37 (dd, J ϭ 2.6, J ϭ 11.4 Hz,
3
): δ ϭ 1.45Ϫ1.68 (m, 4
ϩ
ϩ
ϩ
(%) ϭ 288 (5) [M ], 270 (2) [M Ϫ H
2
O], 243 (23) [M Ϫ OEt],
2
2
ϩ
2
(
2
15 (45) [M Ϫ CO
18), 77 (80). HRMS calcd. for C17
89.1440. The data of 2b were in accordance with the literature.
2
2
2
ϩ
H
20
O
4
2
2
[1b]
(m, 1 H, CH
s, 3 H, CH
2
2
(
3
1
3
1
Ethyl 1-Hydroxy-4-methyl-4-phenyl-2,3-dioxabicyclo[4.4.0]decane-
1 H, CH), 7.29Ϫ7.42 (m, 5 H, CH) ppm. C{ H} NMR
(125 MHz, CDCl ): δ ϭ 19.40 (CH ), 22.33 (CH ), 25.48 (CH ),
6-carboxylate (5d): According to the General Procedure, 1b (90 mg,
0.53 mmol), CeCl ·7H O (10 mg, 0.027 mmol), and 4b (125 mg,
1.06 mmol) in iPrOH (0.2 mL) were converted. By chromatography 78.55 (CH), 101.93 (C), 126.94 (CH), 128.56 (CH), 128.77 (CH),
3
2
2
2
3
2
2 2 2 3
26.91 (CH ), 37.87 (CH ), 38.70 (CH ), 51.85 (CH ), 52.00 (C),
(
SiO
2
, PE:EA, 5:1), alcohol 2b (R
f
ϭ 0.19, 25 %) was separated, 137.69 (C), 175.39 (C) ppm. The data of 2c were in accordance
with the literature.[
1b]
and 5d was obtained as colorless crystals (R
0
1
f
ϭ 0.36, 69 mg,
.22 mmol, 42 %), m.p. 121 °C. H NMR (500 MHz, CDCl ): δ ϭ
.07 (br. t, J ϭ 6.4 Hz, 3 H, CH ), 1.41 (br. s, 3 H, CH ), 1.57Ϫ1.64
1
3
Methyl 7-Hydroxy-10-methyl-10-phenyl-8,9-dioxabicyclo[5.4.0]un-
3
3
(
m, 2 H), 1.66Ϫ1.82 (m, 5 H), 2.36Ϫ2.51 (m, 1 H), 2.56 (br. d, J ϭ decane-1-carboxylate (5f): According to the General Procedure, 1c
1
3
7
3 2
4.1 Hz, 1 H), 2.83 (d, J ϭ 14.3 Hz, 1 H), 3.09Ϫ3.16 (m, 1 H), (291 mg, 1.71 mmol), CeCl ·7H O (30 mg, 0.081 mmol), and 4b
.66Ϫ3.73 (m, 1 H), 6.98 (br. s, 1 H, OH), 7.18Ϫ7.22 (m, 1 H), (393 mg, 3.33 mmol) in iPrOH (0.5 mL) were converted. Filtration
.29Ϫ7.32 (m, 2 H), 7.46Ϫ7.48 (m, 2 H) ppm. 13C{ H} NMR
1
through a short column of SiO
), consisting of diastereomers A, B, C and D of 5f in a ratio
), 45.82 (C),
38:25:23:14 (288 mg, 0.899 mmol, 53 %) and alcohol 2c (54 mg,
), 82.30 (C), 102.24 (C), 126.10 (CH), 126.73 (CH), 0.290 mmol, 17 %). Alcohol 2c was separated by repeated chroma-
27.56 (CH), 142.69 (C), 177.03 (C) ppm. IR (ATR): ν˜ ϭ 3316 (br.
tography (SiO , PE:EA, 10:1), and two product-containing frac-
2
(PE:EA, 10:1) gave a crude fraction
(63 MHz, CDCl
3
): δ ϭ 13.42 (CH
3
), 20.37 (CH
2 2
), 22.34 (CH
3
6
1
0.39 (CH
3
), 30.65 (CH ), 33.48 (CH
2
2
), 39.73 (CH
2
0.83 (CH
2
2
s), 2937 (m), 1688 (s), 1456 (s), 1444 (s), 1370 (m), 1324 (m), 1265 tions were obtained. The first fraction contained diastereomers A
Ϫ1
(
m), 1204 (s), 1186 (s), 1172 (s), 1095 (m) cm . MS (FAB, and D [R
f
(PE/EA, 5:1) ϭ 0.28, A:D, 80:20] as a colorless oil, and
the second fraction contained diastereomers B and C [R (PE/EA,
67), 269 (7), 229 (9), 209 (100), 185 (25), 170 (14), 132 (17), 105 5:1)ϭ 0.34Ϫ0.44, B:C, 40:60] as a colorless solid. Diastereomers A
ϩ
ϩ
glycerol): m/z (%) ϭ 321 (58) [MH ], 303 (18) [MH Ϫ H
2
O], 287
f
(
(
1
24). C18
H
24
O
5
(320.38): calcd. C 67.48, H 7.55; found C 67.54, and D: H NMR (500 MHz, CDCl
3
): δ ϭ 1.16Ϫ1.28 (m, 2 H), 1.31
H 7.52.
(s, 3 H, CH , isomer A), 1.43Ϫ1.60 (m, 5 H), 1.61 (s, 3 H, CH ,
3
3
isomer D), 1.63Ϫ1.70 (m, 1 H), 1.70Ϫ1.87 (m, 8 H), 1.87Ϫ2.00 (m,
2 H), 2.12 (dd, J ϭ 14.6, J ϭ 8.9 Hz, 1 H, isomer A), 2.23 (d, J ϭ
Methyl 7-Hydroxy-10-phenyl-8,9-dioxabicyclo[5.4.0]undecane-1-car-
boxylate (5e): According to the General Procedure, 1c (272 mg, 14.0 Hz, 1 H, isomer D), 2.24 (d, J ϭ 14.0 Hz, 1 H, isomer A),
1
.60 mmol), CeCl
.23 mmol) in iPrOH (0.5 mL) were converted. Chromatography D), 2.70 (d, J ϭ 14.0 Hz, 1 H, isomer A), 3.39 (s, 1 H, OH, isomer
, PE:EA, 10:1) gave a crude fraction consisting of dia- D), 3.79 (s, 3 H, CH , isomer D), 3.79 (s, 3 H, CH , isomer A),
stereomers A, B and C of 5e in a ratio of 38:35:27 (264 mg,
.862 mmol, 54 %) and alcohol 2c (137 mg, 0.735 mmol, 46 %). By
repeated chromatography (SiO , PE:EA, 10:1) 2c was separated,
and two product-containing fractions were obtained. The first frac-
tion contained diastereomers A and B [R (SiO , PE:EA, 5:1) ϭ
.32] as a colorless oil. The second fraction contained diastereomer
C [R (SiO , PE:EA, 5:1) ϭ 0.16] as a colorless oil. Diastereomers
A and B: H NMR (500 MHz, CDCl
CH ), 1.59Ϫ1.69 (m, 4 H, CH ), 1.70Ϫ1.86 (m, 5 H, CH
.88Ϫ1.97 (m, 2 H, CH ), 2.03 (ddd, J ϭ 12.4, J ϭ 5.3, J ϭ
4.3 Hz, 1 H, CH , isomer B), 2.11Ϫ2.16 (m, 2 H, CH ), 2.21Ϫ2.30
), 2.36 (dd, J ϭ 12.2, J ϭ 14.0 Hz, 1 H, CH , isomer and C: M.p. 124Ϫ129 °C. H NMR (500 MHz, CDCl
B), 2.40Ϫ2.44 (m, 1 H, CH , isomer B), 2.56 (dd, J ϭ 4.0, J ϭ 1.22Ϫ1.37 (m, 2 H), 1.38 (s, 3 H, CH , isomer B), 1.39Ϫ1.51 (m,
, isomer A), 3.26 (br. s, 1 H, OH, isomer B), 2 H), 1.53Ϫ1.63 (m, 3 H), 1.57 (s, 3 H, CH , isomer C), 1.67Ϫ1.75
, isomer B), 3.84 (s, 3 H, CH , isomer A), 5.08 (m, 4 H), 1.77Ϫ1.82 (m, 5 H), 1.95Ϫ2.08 (m, 3 H), 2.12Ϫ2.22 (m,
2 H), 2.27 (d, J ϭ 14.3 Hz, 1 H, CH , isomer C), 2.33Ϫ2.39 (m, 1
J ϭ 10.9 Hz, 1 H, CH, isomer A), 7.29Ϫ7.40 (m, 10 H, CH), 7.70 H), 2.69 (d, J ϭ 14.4 Hz, 1 H, CH , isomer C), 2.83 (br. s, 1 H,
br. s, 1 H, OH, isomer A) ppm. IR (ATR): ν˜ ϭ 3338 (br. s), 2930
CH , OH, isomer B), 2.83 (br. s, 3 H, CH , isomer B), 3.03 (s, 3
3
·7H
2
O (30 mg, 0.081 mmol), and 4a (336 mg,
2.43 (d, J ϭ 14.6 Hz, 1 H, isomer D), 2.68Ϫ2.70 (m, 1 H, isomer
3
(
SiO
2
3
3
7.23Ϫ7.25 (m, 3 H, CH, isomer D), 7.28Ϫ7.30 (m, 2 H, CH, isomer
D), 7.33Ϫ7.36 (m, 3 H, CH, isomer A), 7.40Ϫ7.41 (m, 2 H, CH,
isomer A), 7.46 (br. s, 1 H, OH, isomer A) ppm. Diastereomer A:
0
2
1
3
1
C{ H} NMR (75 MHz, CDCl
27.54 (CH ), 28.94 (CH ), 33.48 (CH
50.65 (C), 52.27 (CH
(CH), 128.23 (CH), 147.21 (C), 178.34 (C) ppm. Diastereomer D:
3
): δ ϭ 21.63 (CH
2
), 22.76 (CH
2
),
f
2
3
2
2
), 37.07 (CH
2
), 43.84 (CH
2
),
0
3
), 81.49 (C), 105.40 (C), 124.38 (CH), 126.76
f
2
1
13
1
3
): δ ϭ 1.43Ϫ1.58 (m, 5 H,
C{ H} NMR (75 MHz, CDCl
3
): δ ϭ 23.45 (CH ), 23.60 (CH
3
2
),
),
2
2
2
), 24.85 (CH
2
), 26.48 (CH
2
), 36.00 (CH ), 37.74 (CH ), 43.63 (CH
2
2
2
1
1
2
3
50.37 (C), 51.75 (CH ), 80.29 (C), 102.95 (C), 124.11 (CH), 127.66
2
2
(CH), 128.45 (CH), 145.06 (C), 174.80 (C) ppm. Diastereomers B
1
(m, 2 H, CH
2
2
3
): δ ϭ
2
3
1
3
4.0 Hz, 1 H, CH
.79 (s, 3 H, CH
2
3
3
3
(dd, J ϭ 2.1, J ϭ 12.2 Hz, 1 H, CH, isomer B), 5.09 (dd, J ϭ 4.0,
2
2
(
3
3
Eur. J. Org. Chem. 2003, 4879Ϫ4886
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4883

J. Christoffers, T. Werner, W. Frey, A. Baro
FULL PAPER
H, CH
3
, isomer C), 3.35 (s, 1 H, OH, isomer C), 7.20Ϫ7.26 (m, 2
A and B of 5h in a ratio 7:1 (R
59 %) as a colorless solid. The second fraction contained dia-
stereoisomer C of 5h (R ϭ 0.15, 63 mg, 0.23 mmol, 14%) as a
f
ϭ 0.22Ϫ0.40, 260 mg, 0.934 mmol,
H, CH), 7.33Ϫ7.37 (m, 6 H, CH), 7.46Ϫ7.44 (m, 2 H, CH) ppm.
IR (ATR): ν˜ ϭ 3464 (br. m), 3329 (br. m), 2924 (m), 1696 (s), 1441
f
Ϫ1
1
(
(
2
(
m), 1336 (m), 1215 (m) cm . MS (FAB, glycerol): m/z (%) ϭ 321 colorless solid. Diastereomers A and B: M.p. 140 °C. H NMR
ϩ ϩ ϩ
45) [MH ], 303 (32) [MH Ϫ H
43 (18), 287 (70), 243 (18), 209 (100), 177 (52), 105 (24). C18
320.38): calcd. C 67.48, H 7.55; found C 67.28, H 7.55. Dia-
2
O], 271 (8), [MH Ϫ H
2
O Ϫ O
2
], (300 MHz, CDCl
CH , isomer A), 1.47 (s, 3 H, CH
J ϭ 9.9, J ϭ 13.6 Hz, 1 H, CH , isomer A), 1.67Ϫ1.75 (m, 2 H,
, isomer B), 1.81 (s, 3 H, CH , isomer A), 2.10Ϫ2.16 (m, 1 H,
, isomer A), 2.25 (d, J ϭ 14.2 Hz, 1 H, CHH, isomer B), 2.39
3
): δ ϭ 1.33 (s, 3 H, CH
3
, isomer B), 1.46 (s, 3 H,
H
24
O
5
3
3
, isomer B), 1.54 (ddd, J ϭ 9.8,
2
13
1
stereomer B: C{ H} NMR (75 MHz, CDCl
3
): δ ϭ 22.31 (CH
2
), CH
), CH
2
3
2
4
2.51 (CH
5.12 (CH
2
), 30.05 (CH
2
), 30.31 (CH
3
), 32.11 (CH ), 38.12 (CH
2
2
2
2
), 49.27 (C), 51.20 (CH
3
), 81.84 (C), 107.04 (C), 124.69 (d, J ϭ 14.3 Hz, 1 H, CHH, isomer A), 2.73 (d, J ϭ 14.3 Hz, 1 H,
CHH, isomer A), 2.83 (d, J ϭ 14.2 Hz, 1 H, CHH, isomer B), 3.62
), (s, 1 H, OH, isomer A), 3.99Ϫ4.07 (m, 2 H, CH ), 4.12Ϫ4.22 (m,
), 2 H, CH ), 4.39 (s, 1 H, OH, isomer B), 7.23Ϫ7.30 (m, 2 H, CH),
(CH), 126.53 (CH), 127.90 (CH), 143.88 (C), 178.12 (C) ppm. Dia-
13
1
stereomer C: C{ H} NMR (75 MHz, CDCl
3
): δ ϭ 23.29 (CH
2
2
2
4
4.87 (CH
2.43 (CH
2
), 26.02 (CH
2
), 30.97 (CH
3
), 35.26 (CH ), 37.91 (CH
2
2
2
2
), 49.36 (C), 50.80 (CH
3
), 81.54 (C), 102.50 (C), 125.60 7.33Ϫ7.40 (m, 4 H, CH), 7.45Ϫ7.50 (m, 4 H, CH) ppm. IR (ATR):
(
CH), 126.64 (CH), 127.79 (CH), 142.53 (C), 172.80 (C) ppm. The ν˜ ϭ 3400 (br. s), 1756 (m), 1735 (s), 1447 (m), 1381 (s), 1224 (s),
[1b]
Ϫ1
data of 2c were in accordance with the literature.
1194 (m), 1179 (m), 1029 (s) cm . MS (FAB, glycerol): m/z (%) ϭ
ϩ
ϩ
ϩ
2
79 (50) [MH ], 261 (30) [MH Ϫ H
2
O], 245 (100), 243 (71) [MH
6
-Hydroxy-6-methyl-9-phenyl-2,7,8-trioxaspiro[4.5]decan-1-one Ϫ2 H O], 227 (16), 183 (18), 154 (26), 123 (26), 99 (33). C H O
2
15 18
5
(
5g): According to the General Procedure, 1d (197 mg, 1.54 mmol),
CeCl ·7H O (30 mg, 0.081 mmol) and 4a (342 mg, 3.28 mmol) in
iPrOH (0.5 mL) were converted. Chromatography (SiO , PE:EA,
:1) gave two fractions. The first fraction contained diastereomer
A of 5g (130 mg, 0.492 mmol, 32 %) and ketone 6g (30 mg, 143.37 (C), 178.19 (C) ppm. Diastereomer B: C{ H} NMR
(278.30): calcd. C 64.74, H 6.52; found C 64.35, H 6.49. Dia-
stereomer A: C{ H} NMR (75 MHz, CDCl ): δ ϭ 22.31 (CH ),
3 3
29.91 (CH ), 31.30 (CH ), 42.70 (CH ), 48.81 (C), 67.82 (CH ),
3 2 2 2
1
3
1
3
2
2
2
81.61 (C), 101.87 (C), 125.18 (CH), 126.96 (CH), 128.20 (CH),
1
3
1
0
5
1
.12 mmol, 8 %). The second fraction contained diastereomer B of
3 3 3 2
(75 MHz, CDCl ): δ ϭ 21.62 (CH ), 30.43 (CH ), 31.49 (CH ),
g (129 mg, 0.488 mmol, 32 %) and alcohol 2d (39 mg, 0.27 mmol, 38.91 (CH ), 47.14 (C), 66.12 (CH ), 80.86 (C), 99.14 (C), 125.34
2
2
8 %). By repeated chromatography (SiO
ϭ 0.25) and B (R ϭ 0.13) could be separated
completely. Diastereomer A of 5g (cis): M.p. 145 °C. H NMR
500 MHz, CDCl
.6 Hz, 1 H), 2.21 (ddd, J ϭ 13.0, J ϭ 9.7, J ϭ 9.7 Hz, 1 H), 2.79
dd, J ϭ 14.1, J ϭ 12.2 Hz, 1 H), 2.98 (s, 1 H), 3.15 (ddd, J ϭ 2.3, J ϭ 8.7 Hz, 1 H, CH ), 4.38Ϫ4.43 (m, 1 H, CH ), 7.26Ϫ7.30
2
, PE:EA, 2:1) dia-
(CH), 127.10 (CH), 128.32 (CH), 142.94 (C), 177.99 (C) ppm. Dia-
1
stereoisomer A (R
f
f
stereomer C: H NMR (500 MHz, CDCl ): δ ϭ 1.57 (br. s, 6 H,
3
1
CH ), 2.13 (br. s, 1 H, CH ), 2.27 (ddd, J ϭ 9.3, J ϭ 9.3, J ϭ
3
2
(
2
(
1
3
): δ ϭ 1.90 (s, 3 H), 1.90 (dd, J ϭ 14.1, J ϭ 12.9 Hz, 1 H, CH ), 2.74Ϫ2.79 (m, 1 H, CH ), 3.05 (s, 1 H, OH),
2
2
2
3.15 (ddd, J ϭ 2.3, J ϭ 6.7, J ϭ 12.9 Hz, 1 H, CH ), 4.33 (dt, J ϭ
2
2
1
3
1
3.0, J ϭ 7.5, J ϭ 2.5 Hz, 1 H), 4.34Ϫ4.38 (m, 1 H), 4.43Ϫ4.48
(m, 1 H, CH), 7.34Ϫ7.39 (m, 4 H, CH) ppm. C{ H} NMR
(
m, 1 H), 5.12 (dd, J ϭ 12.3, J ϭ 2.6 Hz, 1 H), 7.34Ϫ7.41 (m, 5 (75 MHz, CDCl ): δ ϭ 21.44 (CH ), 22.67 (CH ), 33.90 (CH ),
3 3 3 2
13
1
H) ppm. C{ H} NMR (125 MHz, CDCl
3
): δ ϭ 22.56 (CH
3
), 40.96 (CH ), 47.48 (C), 67.28 (CH ), 79.56 (C), 99.39 (C), 124.34
2 2
3
1
1
1.34 (CH
2
), 39.67 (CH
2
), 49.52 (C), 67.40 (CH ), 80.21 (CH), (CH), 128.39 (CH), 128.54 (CH), 143.68 (CH), 177.14 (CH) ppm.
2
02.21 (C), 127.30 (CH), 128.79 (CH), 129.30 (CH), 135.92 (C),
ϩ
77.46 (C) ppm. MS (FAB): m/z (%) ϭ 265 (6) [MH ], 246 (70)
2-Benzyl-6-hydroxy-6-methyl-9-phenyl-7,8-dioxa-2-azaspiro[4.5]-
ϩ
[M
Ϫ H
2
O], 231 (100), 189 (12), 133 (33), 109 (30), 99 (17), 75 decan-1-one (5i): According to the General Procedure, 1e (332 mg,
(264.27): calcd. C 63.63, H 6.10; found C 63.68, H
1.53 mmol), CeCl ·7H O (30 mg, 0.081 mmol), and 4a (337 mg,
): 3.24 mmol) in iPrOH (0.5 mL) were converted. Chromatography
δ ϭ 1.49 (s, 3 H), 2.12 (ddd, J ϭ 14.1, J ϭ 8.0, J ϭ 5.7 Hz, 1 H),
(SiO , PE:EA, 5:1) gave two fractions. The first fraction contained
.15 (dd, J ϭ 14.4, J ϭ 2.2 Hz, 1 H), 2.40 (dd, J ϭ 14.0, J ϭ ketone 6i [R (PE:EA, 2:1) ϭ 0.17, 229 mg, 0.683 mmol, 45%] as a
1.8 Hz, 1 H), 2.73 (ddd, J ϭ 8.7, J ϭ 7.7, J ϭ 14.0 Hz, 1 H), 3.49
yellow oil. In the second fraction, 5i was obtained [R (PE:EA,
(76). C14
H
16
O
5
3
2
1
6
.19. Diastereomer B of 5g (trans): H NMR (500 MHz, CDCl
3
2
2
1
f
f
(
s, 1 H), 4.25Ϫ4.39 (m, 2 H), 5.80 (dd, J ϭ 11.7, J ϭ 2.3 Hz, 1 H), 2:1) ϭ 0.14, 28 mg, 0.079 mmol, 5 %] as a colorless solid, m.p. 171
.32Ϫ7.39 (m, 5 H) ppm. 13C{ H} NMR (CDCl
1
, 125 MHz): δ ϭ
), J ϭ 2.1, J ϭ 13.5 Hz, 1 H, CH
1
7
2
7
1
3
°C. H NMR (300 MHz, CDCl
3
): δ ϭ 1.30 (s, 3 H, CH
), 2.15 (ddd, J ϭ 8.5, J ϭ 5.8, J ϭ
3
), 1.63 (dd,
1.26 (CH ), 33.13 (CH ), 35.53 (CH ), 47.11 (C), 64.85 (CH
3
2
2
2
2
8.51 (CH), 99.68 (C), 127.12 (CH), 128.75 (CH), 129.15 (CH), 14.0 Hz, 1 H, CHH), 2.42 (ddd, J ϭ 8.3, J ϭ 5.7, J ϭ 13.9 Hz, 1
1
36.75 (C), 176.72 (CϭO) ppm. Ketone 6g: H NMR (500 MHz,
H, CHH), 2.80Ϫ2.88 (m, 1 H, CH
4.42 (d, J ϭ 14.4 Hz, 1 H, CHH), 4.59 (d, J ϭ 14.4 Hz, 1 H, CHH),
J ϭ 13.1, J ϭ 5.7, J ϭ 3.2 Hz, 1 H), 3.59 (d, J ϭ 18.6 Hz, 1 H), 5.15 (dd, J ϭ 2.0, J ϭ 12.0 Hz, 1 H, CH), 5.85 (s, 1 H, OH),
2 2
), 3.21Ϫ3.35 (m, 2 H, CH ),
3
CDCl ): δ ϭ 2.15 (t, J ϭ 13.2 Hz, 1 H), 2.29 (s, 3 H), 3.12 (ddd,
1
3
1
4.00 (d, J ϭ 18.5 Hz, 1 H), 4.42Ϫ4.52 (m, 2 H), 7.48Ϫ7.52 (m, 2
7.22Ϫ7.25 (m, 2 H, CH), 7.30Ϫ7.42 (m, 8 H, CH) ppm. C{ H}
H), 7.61Ϫ7.64 (m, 1 H), 7.96Ϫ7.98 (m, 2 H) ppm. C{ H} NMR NMR (75 MHz, CDCl ): δ ϭ 22.31 (CH ), 27.37 (CH ), 35.77
125 MHz, CDCl ): δ ϭ 25.70 (CH ), 31.34 (CH ), 44.20 (CH ),
(CH ), 43.89 (CH ), 47.21 (CH ), 48.71 (C), 78.71 (CH), 100.25
8.32 (C), 67.14 (CH
), 128.16 (CH), 128.90 (CH), 134.10 (CH), (C), 127.44 (CH), 128.10 (CH), 128.28 (CH), 128.62 (CH), 128.95
35.62 (C), 175.18 (CϭO), 196.09 (CϭO), 201.00 (CϭO) ppm. MS (CH), 129.07 (CH), 135.48 (C), 136.95 (C), 175.64 (C) ppm. IR
13
1
3
3
2
(
3
3
2
2
2
2
2
5
1
2
ϩ
(
(
CI): m/z (%) ϭ 247 (52) [MH ], 229 (67), 205 (30), 185 (100), 169 (ATR): ν˜ ϭ 3227 (br. s), 2951 (m), 1651 (s), 1494 (m), 1451 (m),
Ϫ1
1), 127 (11), 105 (41), 97 (5), 51 (5). The data of 2d were in accord-
1290 (m), 1244 (m), 1124 (m), 1097 (s) cm . MS (FAB): m/z (%) ϭ
[
1b]
ϩ
ϩ
ance with the literature.
354 (32) [MH ], 336 (61) [MH Ϫ H
2
O], 320 (24), 296 (11), 275
(
15), 245 (12), 215 (16), 188 (26), 183 (32), 91 (100). HRMS calcd.
ϩ
6
(
-Hydroxy-6,9-dimethyl-9-phenyl-2,7,8-trioxaspiro[4.5]decan-1-one for C21
5h): According to the General Procedure, 1d (202 mg, 1.58 mmol), (353.16): calcd. C 71.37, H 6.56, N 3.96; found C 71.19, H 6.54, N
CeCl ·7H O (30 mg, 0.081 mmol), and 4b (379 mg, 3.21 mmol) in
iPrOH (0.5 mL) were converted. Chromatography (SiO , PE:EA, 7.8, J ϭ 9.6, J ϭ 13.4 Hz, 1 H, CH
:1) gave two fractions. The first fraction contained diastereoisomer J ϭ 2.7, J ϭ 8.2, J ϭ 13.4 Hz, 1 H, CH
4 4
H23NO : 354.1705 [MH ]; found 354.1724. C21H23NO
1
3
2
3.19. Ketone 6i: H NMR (300 MHz, CDCl
), 2.25 (s, 3 H, CH
), 3.25 (ddd, J ϭ 9.6, J ϭ
3
): δ ϭ 1.84 (ddd, J ϭ
2
2
3
), 2.92 (ddd,
5
2
4884
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4879Ϫ4886

Cerium-Catalyzed Reaction of β-Dicarbonyl Compounds
FULL PAPER
Table 2. X-ray crystallographic data for 5g and 5h
cis-5g
trans-5g
cis-5h
trans-5h
Empirical formula
Formula mass [g molϪ1]
Crystal system
C
14
H
16
O
5
C
14
H
16
O
5
C
15
H
18
O
5
15 18 5
C H O
264.27
monoclinic
P2 /c
10.9452(6)
11.6229(8)
10.3322(9)
102.948(6)
4
264.27
monoclinic
P2 /c
6.5947(2)
15.5436(6)
12.8034(9)
102.690(5)
4
278.28
monoclinic
P2 /c
8.1593(9)
10.7326(8)
15.6899(11)
92.689(7)
4
278.28
monoclinic
P2 /c
Space group
1
1
1
1
˚
a (A)
8.3476(12)
16.156(3)
10.6008(13)
103.217(10)
4
1391.8(3)
1.328
˚
b (A)
˚
c (A)
β [°]
Z
V (A )
˚
3
1280.99(16)
1.370
0.1703
1280.36(11)
1.371
0.1573
1372.5(2)
1.347
0.1567
δ
R
calcd. [g cmϪ3
]
w
(F2)
R(F) [I Ͼ 2σ(I)]
0.0991
0.0582
0.0639
0.0560
0.0513
2
1
1
.7, J ϭ 9.7 Hz, 1 H, CH
2.6 Hz, 1 H, CH
8.7 Hz, 1 H, CH
2
), 3.43 (ddd, J ϭ 8.0, J ϭ 8.1, J ϭ
2 2
44.41 (CH ), 47.26 (CH ), 50.35 (C), 80.50 (C), 99.81 (C), 125.46
2
), 3.46 (d, J ϭ 18.8 Hz, 1 H, CH
2
), 4.12 (d, J ϭ (CH), 126.72 (CH), 128.02 (CH), 128.09 (CH), 128.37 (CH), 128.86
2
), 4.44Ϫ4.54 (m, 2 H, CH ), 7.20Ϫ7.24 (m, 2 H, (CH), 135.52 (C), 143.89 (C), 175.56 (C) ppm.
2
CH), 7.27Ϫ7.39 (m, 3 H, CH), 7.46Ϫ7.51 (m, 2 H, CH), 7.57Ϫ7.63
m, 1 H, CH), 7.97Ϫ7.98 (m, 1 H, CH), 7.99Ϫ8.01 (m, 1 H, CH)
Transformation of Hydroperoxide 5a into Dioxo Ester 6a: AcCl
100 mg, 1.3 mmol) was added at 0 °C to a solution of 5a (165 mg,
.56 mmol) and pyridine (112 mg, 1.4 mmol) in CH Cl (0.5 mL),
and the reaction mixture was stirred at room temp. for 20 h. After
removal of all volatile materials under vacuum, the residue was
(
(
0
13
1
ppm. C{ H} NMR (63 MHz, CDCl
3
): δ ϭ 26.11 (CH
3
), 27.78
2
2
(
(
(
CH
2
), 44.60 (CH
2
), 44.71 (CH
2
), 47.31 (CH ), 60.21 (C), 127.77
2
CH), 128.06 (CH), 128.13 (CH), 128.76 (CH), 128.81 (CH), 133.70
CH), 135.87 (C), 136.18 (C), 171.56 (C), 197.20 (C), 203.95 (C)
purified by chromatography on SiO
to give 6a as a colorless oil (121 mg, 0.44 mmol, 78 %). H NMR
300 MHz, CDCl ): δ ϭ 1.24 (t, J ϭ 7.1 Hz, 3 H), 2.03Ϫ2.17 (m,
H), 2.53Ϫ2.69 (m, 3 H), 3.48 (d, J ϭ 18.6 Hz, 1 H), 3.86 (d, J ϭ
8.6 Hz, 1 H), 4.17 (q, J ϭ 7.1 Hz, 2 H), 7.43Ϫ7.49 (m, 2 H),
2 f
with PE/EA, 5:1 (R ϭ 0.22)
ppm. IR (ATR): ν˜ ϭ 1712 (m), 1679 (s), 1449 (m), 1430 (m), 1260
1
Ϫ1
ϩ
(
(
(
m), 1215 (m) cm . MS (EI, 70 eV): m/z (%) ϭ 335 (45) [M ], 292
(
3
ϩ
ϩ
20) [M Ϫ COMe], 215 (43) [M Ϫ COMe Ϫ Ph], 188 (99), 105
34), 91 (100). HRMS calcd. for C21H21NO : 335.1521 [M ];
3
3
1
7
ϩ
found 335.1521.
1
3
1
.55Ϫ7.60 (m, 1 H), 7.93Ϫ7.97 (m, 2 H) ppm. C{ H} NMR
): δ ϭ 14.00 (CH ), 19.86 (CH ), 33.40 (CH ),
), 43.48 (CH ), 57.47 (C), 61.66 (CH ), 128.11 (CH),
O (10 mg, 0.027 mmol), and 4b 128.65 (CH), 133.47 (CH), 136.31 (C), 170.71 (C), 196.74 (C),
2
-Benzyl-6-hydroxy-6,9-dimethyl-9-phenyl-7,8-dioxa-2-azaspiro-
(125 MHz, CDCl
37.76 (CH
3
3
2
2
[4.5]decan-1-one (5j): According to the General Procedure, 1e
2
2
2
(
(
126 mg, 0.580 mmol), CeCl
126 mg, 1.06 mmol) in iPrOH (0.2 mL) were converted. Chroma-
, PE:EA, 2:1) gave a fraction containing dia-
stereomers A and B of 5j in a ratio 60:40 (R ϭ 0.19, 110 mg,
.299 mmol, 52 %) as a colorless solid, m.p. 144 °C. 1H NMR
500 MHz, CDCl ): δ ϭ 1.15 (s, 3 H, CH
, isomer B), 1.24Ϫ1.29 70.06, H 6.61; found C 69.57, H 6.62.
m, 1 H, CH , isomer A), 1.40Ϫ1.46 (m, 1 H, CH , isomer B), 1.48
s, 3 H, CH , isomer A), 1.49 (s, 3 H, CH
m, 1 H, CH , isomer A), 1.88 (s, 3 H, CH
3
·7H
2
215.11 (C) ppm. IR (film): ν˜ ϭ 1755 (s), 1721 (s), 1684 (s), 1451
tography (SiO
2
(m), 1401 (m), 1359 (m), 1285 (m), 1224 (s), 1186 (m), 1153 (m),
Ϫ1
18 4
1105 (m), 1039 (m), 1001 (m) cm . HRMS for C16H O
(70 eV,
f
0
EI): calcd. 274.1205, found 274.1205. C16H O (274.32): calcd. C
18 4
(
(
(
(
3
3
2
2
3
3
, isomer A), 1.76Ϫ1.77 Acknowledgments
2
3
, isomer A), 2.19 (d,
The authors acknowledge support by the Deutsche Forschungsge-
meinschaft and the Fonds der Chemischen Industrie.
J ϭ 14.0 Hz, 1 H, CHH, isomer B), 2.35 (d, J ϭ 14.6 Hz, 1 H,
CHH, isomer A), 2.81Ϫ2.87 (m, 2 H, CH ), 2.85 (d, J ϭ 14.0 Hz,
H, CHH), 2.93Ϫ2.98 (m, 1 H, CH , isomer B), 3.00Ϫ3.05 (m, 1
H, CH , isomer B), 3.17Ϫ3.22 (m, 1 H, CH , isomer A), 3.32Ϫ3.37
m, 1 H, CH , isomer A), 4.38 (d, J ϭ 14.0 Hz, 1 H, CHH, isomer
B), 4.42 (d, J ϭ 14.6 Hz, 1 H, CHH, isomer A), 4.54 (d, J ϭ
4.6 Hz, 1 H, CHH, isomer A), 4.59 (d, J ϭ 14.0 Hz, 1 H, CHH,
isomer B), 5.54 (s, 1 H, OH, isomer B), 7.22Ϫ7.23 (m, 2 H, CH),
.25Ϫ7.30 (m, 5 H, CH, OH), 7.30Ϫ7.34 (m, 2 H, CH), 7.34Ϫ7.39
2
1
2
[
1] [1a]
J. Christoffers, T. Werner, Synlett 2002, 119Ϫ121. [1b] J.
2
2
Christoffers, T. Werner, S. Unger, W. Frey, Eur. J. Org. Chem.
(
2
2
003, 425Ϫ431.
[2]
Due to the high charge density at the metal center, mixtures of
1
β-dicarbonyls and trivalent cations are Brønsted acids. More-
4ϩ
3ϩ
over, the normal potential Ce /Ce is strongly reduced by
complexation.
7
[3] [3a]
(
m, 8 H, CH), 7.50Ϫ7.53 (m, 4 H, CH) ppm. IR (ATR): ν˜ ϭ 3317
V. Nair, J. Mathew, J. Prabhakaran, Chem. Soc. Rev. 1997,
127Ϫ132. [ T. Linker, M. Schmittel, Radikale und Radikal-
ionen in der Organischen Synthese, Wiley-VCH, Weinheim,
3b]
(
br. s), 1670 (s), 1495 (m), 1453 (m), 1444 (m), 1212 (m), 1178 (m),
126 (m), 1067 (m) cm . C22H25NO (367.43): calcd. C 71.91, H
4
Ϫ1
1
6
1
998, p. 205Ϫ241.
.86, N 3.81; found C 72.18, H 6.69, N 3.73. Diastereomer A:
[4]
1
3
1
T. Linker, U. Linker, Angew. Chem. 2000, 112, 934Ϫ936; An-
gew. Chem. Int. Ed. 2000, 39, 902Ϫ904.
C{ H} NMR (63 MHz, CDCl
3
): δ ϭ 22.65 (CH
3
), 28.37 (CH
2
),
3
8
1
1
0.23 (CH ), 42.78 (CH ), 45.43 (CH
1.68 (C), 103.00 (C), 125.28 (CH), 126.58 (CH), 127.36 (CH),
27.83 (CH), 127.98 (CH), 128.54 (CH), 136.36 (C), 144.89 (C),
3
2
2
), 46.85 (CH
2
), 50.62 (C),
[5] [5a]
G. Bar, F. Bini, A. F. Parsons, Synth. Commun. 2003, 33,
[5b]
2
13Ϫ222.
S. Muthusamy, C. Gunanathan, S. A. Babu, Syn-
[5c]
lett 2002, 787Ϫ789.
C.-C. Tseng, Y.-L. Wu, C.-P. Chuang,
13
1
[5d]
74.13 (C) ppm. Diastereomer B: C{ H} NMR (63 MHz,
): δ ϭ 21.72 (CH ), 27.87 (CH ), 30.75 (CH ), 38.84 (CH ),
Tetrahedron 2002, 58, 7625Ϫ7633.
V. Nair, J. Mathew, L.
G. Nair, Synth. Commun. 1997, 27, 3053Ϫ3064. [ V. Nair, J.
5e]
CDCl
3
3
2
3
2
Eur. J. Org. Chem. 2003, 4879Ϫ4886
www.eurjoc.org
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
4885

J. Christoffers, T. Werner, W. Frey, A. Baro
FULL PAPER
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[
R. Kumabe, H. Nishino, M. Yasutake, V.-H. Nguyen, K.
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2
083Ϫ2086.
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F. A.
[
[
6]
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5
75Ϫ591. [
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[12d]
7] [7a]
J. Ouyang, H. Ni-
C. Bosman, A. DЈAnnibale, S. Resta, C. Trogolo, Tetra-
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7b]
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1
783Ϫ1792. [
C.-Y. Qian, H. Nishino, K. Kurosawa, J. Het-
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[14]
[15]
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2
[8c]
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8d]
8e]
CCDC-207609 (5g, cis), CCDC-207610 (5g, trans), CCDC-
14674 (5h, cis) and CCDC-214675 (5h, trans) contain the sup-
[
8f]
36, 9039Ϫ9042.
C. Bosman, A. DЈAnnibale, S. Resta, C.
2
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plementary crystallographic data for this paper. These data can
be obtained free of charge at www.ccdc.cam.uk/conts/retriev-
ing.html [or from the Cambridge Crystallographic Data
Center, 12 Union Road, Cambridge CB2 1EZ, UK; Fax: (in-
ternat.) ϩ 44-1223/336-033; E-mail: deposit@ccdc.cam.ac.uk].
Received July 15, 2003
[
9]
7
257Ϫ7265.
[
10] [10a]
G. Bar, A. F. Parsons, C. B. Thomas, Synlett 2002,
[
10b]
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4886
 2003 Wiley-VCH Verlag GmbH & Co. KGaA, Weinheim
www.eurjoc.org
Eur. J. Org. Chem. 2003, 4879Ϫ4886